student to make the dissections and preparations necessary for studying
the ligaments. Rather should these be examined on demonstration
preparations preserved in the laboratory. Such preparations may most
easily be made by using _fresh_ material, and dissecting away muscles
and other tissues, leaving only the ligaments connecting the bones. The
preparations are then preserved in one or two per cent. formalin. It is
difficult to prepare the ligaments satisfactorily on preserved material,
because they do not stand out clearly from other tissues in such
material, so that they are not easily distinguishable.

MUSCLES.

_Preparation and Preservation of Material._--Formalin forms by far the
most satisfactory preservative for anatomical material. It is much
better in almost every respect than alcohol, and has the additional
advantage of being much cheaper.

After injecting with formalin, the cat may be preserved either immersed
in a weaker solution of the same substance, or may be kept for a long
time simply wrapped in a cloth dampened with formalin. The details of
preparation differ according to which method is to be used.

In either case, the cat should be killed with chloroform, by placing it
in a tight jar or box with a cloth or bit of cotton saturated with
chloroform. It is not necessary to bleed the specimen. When the cat is
dead, remove it to a tray, place it on its back, and tie the limbs
loosely so that they will remain outspread.

Expose the femoral artery in the thigh, as follows: Make a median
longitudinal incision through the skin of the abdomen, from a point an
inch or two caudad of the xiphoid process to the pubis. Make an incision
passing from near the middle of this obliquely laterad onto the thigh,
for about three inches. Reflect the two flaps in the angles between
these cuts, then with forceps and tracer isolate the femoral artery just
as it passes into the thigh (Fig. 127, _a_). Make with scissors an
oblique incision in one side of the artery, one-half to one inch from
the point where it leaves the abdominal cavity. Introduce a canula
directed toward the body, and tie it in place.

1. If the cat is to be preserved immersed in a solution of formalin, it
should now be injected with a five per cent. solution of commercial
formalin in ordinary water (commercial formalin 5 parts; water 95
parts). Into an adult cat 300 to 400 cubic centimeters of the five per
cent. formalin should be injected.

The cat may now be preserved in a one per cent. solution of formalin.
Before immersing it in the formalin it is well to remove the hair in
some way, otherwise this will hold much water and be very inconvenient
in dissection. The neatest method is to cut off the hair with scissors;
this takes some time, however. If the skin-muscles (p. 93) are not to be
dissected, the skin may be removed. It is well in this case to leave the
skin on the sides of the head and on the feet.

It is not necessary to open the abdominal cavity, after injecting with
the five per cent. formalin. If there is at any time reason to suspect
that the viscera are not keeping well, the abdominal and thoracic
cavities should be filled with five per cent. formalin by making a small
hole through the body wall into the cavity, introducing a canula, and
injecting till the cavity is full.

The specimen should be kept in a jar or other vessel and should be
completely immersed beneath the one per cent. formalin. Any parts
projecting above the fluid may be attacked by mould. If a part is found
to be moulded, it should be submerged, when the mould will be killed.
The mould injures the specimen if allowed to grow for a long time, but
if discovered soon, no very serious harm results.

During dissection, exposed parts of the body should be kept from drying
by covering with a damp cloth. Specimens preserved in formalin dry out
much less quickly than those preserved in alcohol.

2. For some purposes it is much more convenient to preserve the material
without immersing it in a vessel of formalin. Specimens injected with
five per cent. formalin, as above directed, would usually keep perfectly
without further treatment, but for two difficulties: (1) the specimen
may _dry_; (2) it may be attacked by mould.

The drying may be prevented as follows: Use for injecting a mixture of
the five per cent. formalin with one-sixth its volume of glycerine. This
will dry only very slowly, and if pains are taken to keep exposed parts
covered with cloths dampened with the mixture of formalin and glycerine,
there will be no trouble from this source. The skin should not be
removed from such specimens except as necessary in the course of
dissection. The hair will give little trouble, because dry.

The specimens should be kept in a tight box, that the fluid may not
evaporate rapidly from the cloths used for wrapping.

The attacks of the mould present a difficulty not so easily overcome. As
long as the specimens are in daily use for dissection, and exposed parts
kept covered with cloths saturated with the glycerine and formalin
mixture, little or no trouble is to be anticipated. But if the specimens
are left untouched for some days, and particularly if exposed surfaces
are not kept covered in the manner above recommended, mould is almost
sure to attack them. Material neglected for a week may thus be ruined.

If mould is found at any time to be attacking the material, the attacked
part should be cleaned and well wrapped in cloths saturated in the
formalin-glycerine mixture. If such means are unavailing, the specimen
should be immersed in a vessel of one per cent. formalin and preserved
for the future in this. Recourse should be had at once also to this
method of preservation if the specimen shows signs of decomposition by
having a strong odor.

It seems probable that the attacks of the mould might be prevented by
mixing some fungicide with the injecting fluid; experiments should be
made in this direction.

There are many advantages in preserving the material if possible without
immersing it. All parts retain their color and pliability much more
completely, so that the different structures are much more easily
distinguishable. The method above described, by the use of formalin and
glycerine, is to be recommended when the material is to be worked on
every day or so and is not to be kept longer than a few weeks. It is
usually not very satisfactory in warm weather, however. If some method
can be devised of entirely preventing the attacks of the mould, this
will be an excellent method of preserving anatomical material.

The same specimens used for the study of the muscles will serve also for
the spinal cord and brain if prepared by one of the methods above
described. (For the viscera, blood-vessels, and nerves, other specimens
will have to be prepared; for these, directions are given later.)

_Muscles to be Dissected._--It will probably usually be impossible in a
given course of study to dissect all the muscles of the cat. The
instructor will of course select such as seem most advisable to him. The
following may perhaps be recommended as a good selection for a fairly
extensive course: Muscles of the Fore Limbs (pp. 436-439); Muscles of
the Neck and the Deep Muscles of the Head (pp. 439-441); Muscles of the
Wall of the Thorax and of the Abdomen (pp. 441-442); Muscles on the
Ventral Side of the Neck (p. 442). If the superficial facial muscles
(excluding those of the ear) can be studied from a preparation, this
will be a valuable addition to a course (pp. 434-435).

DISSECTION OF MUSCLES.

_General._--In dissecting muscles a prime requisite of successful
dissection is to keep the muscles _clean_. Fat, connective tissue, etc.,
is to be carefully but thoroughly cleared away from the surface of
muscles and from between them. Frequently when it seems impossible to
distinguish the structures described, all difficulty will vanish as soon
as the dissection is thoroughly cleaned.

In transecting a muscle, work under it completely from one edge to the
other (except in case of very wide muscles), then introduce the scissors
or scalpel, and cut it by a smooth clean cut. Always leave the entire
origin with one-half of the muscle, the entire insertion with the other
half.

The student must be prepared to find in some cases considerable
variations from the conditions described. The descriptions attempt to
give an account of the _usual_ structures, but specimens showing no
variations whatever are undoubtedly rare.

DIRECTIONS FOR DISSECTING THE MUSCLES OF THE CAT.

I. THE SKIN-MUSCLES (pp. 93-96, and Fig. 62).

These will perhaps not usually be dissected. If they are to be
dissected, proceed as follows: Make a ventral median longitudinal
incision of the skin from the cranial end of the manubrium to a point
opposite the crest of the ilium. Connect the cranial end of this
incision with the middle of the lambdoidal ridge by a similar incision
through the skin. Make another incision from the manubrium to the
spinous process of the thirteenth thoracic vertebra. Connect the caudal
end of the first incision by an oblique cut with the root of the tail.
Make another incision from the convexity of the knee-joint along the
fold of skin which connects the hind limb and body, as far as the
incision which leads to the root of the tail. Make an incision
surrounding the base of the forelimb. Now reflect these flaps one at a
time, working in general from the ventral side toward the dorsal middle
line. Take great pains not to take up the thin skin-muscle with the
skin. In this way all of one side of the body will be uncovered. The
cutaneus maximus (Fig. 62, _b_) and a part of the platysma (Fig. 62,
_a_) will be thus exposed. Read and verify the descriptions of these
muscles (pp. 93-96). The cranial portion of the platysma cannot be seen
at this stage, but should be dissected in connection with the muscles of
the face.

II. SUPERFICIAL MUSCLES OF THE FACE AND HEAD (pp. 96-107, and Figs. 63
and 64).

These will perhaps not usually be dissected by the student. They should
be studied on a well-dissected laboratory preparation, if possible. If
they are to be dissected, this should be done if possible on a fresh
specimen, as it is very difficult to dissect them on preserved material.
Proceed as follows:

The skin should be removed with care from the sides and top of the face
and head, without injury to the external ear.

 1. The platysma (p. 95, and Fig. 62, _a_). Determine its cranial
attachments.

 2. The intermedius scutulorum (p. 96, and Fig. 63, _a_).

 3. The corrugator supercilii medialis (Fig. 63, _b_).

 4. The orbicularis oculi (Fig. 63, _c_; Fig. 64, _s_).

 5. The corrugator supercilii lateralis (Fig. 64, _k_).

 6. Notice the frontoauricularis if it exists.

 7. The levator auris longus (Fig. 63, _g_, _g′_). Transect and reflect.

 8. The auricularis superior (Fig. 63, _k_). Transect.

 9. The abductor auris longus (Fig. 63, _m_). Transect.

10. The abductor auris brevis (Fig. 63, _l_). Transect.

11. The epicranius (Fig. 63, _h_, _h′_). In dissecting this muscle the
intermedius scutulorum and corrugator supercilii medialis may be cut by
an incision parallel to the middle line but a short distance to one side
of it.

12. The zygomaticus (Fig. 64, _d_). This and the two following muscles
may usually be best seen running beneath the fibres of the platysma,
without reflecting the latter. If necessary, however, the platysma may
be transected and reflected, though this can be done only with great
difficulty.

13. The submentalis (Fig. 64, _c_).

14. The depressor conchæ (Fig. 64, _b_).

The zygomaticus, submentalis, and depressor conchæ should now be
transected one or two centimeters from the external ear. The
corrugatores supercilii lateralis and medialis may be cut across between
the eye and the ear, and reflected. There is thus exposed:

15. The frontoscutularis. Transect near the scutiform cartilage.

16. The adductor auris inferior (Fig. 64, _o_). Transect near its
insertion.

The external ear is now attached to the head only by the external
auditory meatus and the tragicus lateralis muscle. Read the description
of the latter (p. 418, and Fig. 67, _a_), find it beneath the fat which
surrounds the proximal portion of the external ear, and cut it as far
ventrad as possible. Now cut across the cartilaginous auditory meatus as
near to the tympanic bone as possible, and remove the external ear,
preserving it for future study. (The remainder of the muscles of the
external ear may be studied in connection with the study of the auditory
organ.)

17. The orbicularis oris (p. 105 and Fig. 64, _i_).

18. The zygomaticus minor, if it exists (p. 105, and Fig. 64, _e_).

19. The quadratus labii superioris (p. 105).

  _a._ The levator labii superioris proprius (Fig. 64, _f_).

  _b._ The levator labii superioris alæque nasi (Fig. 64, _g_).

20. The caninus (p. 106, and Fig. 64, _f′_).

21. The buccinator (p. 106).

22. The myrtiformis (p. 106, and Fig. 64, _h_).

23. The “moustachier” (p. 107).

24. The quadratus labii inferioris (p. 107).

III. MUSCLES OF THE FORE LIMB.

A. _Muscles connecting the Arm with the Body._--If the skin-muscles have
been dissected, as above, cut the cutaneus maximus near its insertion,
and reflect it toward the median dorsal line; in this way remove it
completely. Remove the platysma in the same way. The first layer of
body-muscles is thus exposed.

If the skin-muscles are not to be dissected, these may be removed with
the skin. If the skin has not yet been removed, proceed as follows:

Beginning at the cranial end of the manubrium make two incisions in the
skin, one passing to the lambdoidal ridge and the other to the spinous
process of the thirteenth thoracic vertebra. Raise the triangular flap
thus formed, taking up the skin-muscles with it.

 1. The trapezius group of muscles (pp. 115-117, and Fig. 68, _d_, _h_,
and _j_) is now exposed and may be dissected. Begin with the
spinotrapezius (Fig. 68, _j_). Read the description of the muscle, then
raise its caudal border and work under it until its cranial border is
reached and the middle of its inner surface is free. Then transect it,
and reflect the two halves of the muscle toward the origin and
insertion, clearing the fat, etc., from the inner surface of the muscle
and the parts covered by it. Determine origin and insertion.

 2. The acromiotrapezius (Fig. 68, _h_). Dissect in the same manner,
being careful not to injure the broad thin tendon which connects the two
muscles across the middle line.

 3. The clavotrapezius (Fig. 68, _d_). Separate it carefully, from the
cleidomastoid (p. 120). Transect and reflect, as before.

 4. The occipitoscapularis (Fig. 73, _a_, p. 149). Note the strong
fascia which separates it from the deeper muscles of the neck. Be
careful not to injure adjacent muscles in tracing this toward origin
and insertion. Transect.

 5. The rhomboideus. Transect.

Recognize the levator scapulæ ventralis (Fig. 68, _f_), the
sternomastoid (Fig. 68, _c_; Fig. 65, _g_), and the cleidomastoid (Fig.
65, _h_). Then dissect--

 6. The levator scapulæ ventralis (Fig. 68, _f_). Its origin (Fig. 72,
_c_, _c′_) cannot be seen at this stage and should be left until the
cervical muscles are dissected. Be careful in transecting this muscle to
separate it well from the cleidomastoid. Transect.

 7. The cleidomastoid (Fig. 65, _h_). Its origin cannot be fully seen at
this stage. Transect.

Make a midventral incision of the skin from the cranial end of the
manubrium to a point opposite the crest of the ilium. From the caudal
end of this incision make an incision to the root of the tail. From the
cranial end of the incision in the ventral middle line make a cut around
the base of the fore limb on its caudal side, thus connecting the
ventral incision with the incision which passes between the manubrium
and the thirteenth thoracic vertebra.

Make another incision from the convexity of the knee at the joint along
the fold of the skin which connects the hind limb and body, to the
incision which leads to the root of the tail.

Reflect the flaps thus formed so as to expose the body and flank,
removing the skin-muscle with the skin.

 8. The latissimus dorsi (p. 121, and Fig. 68, _m_). Dissect it up and
transect it. Work carefully toward its insertion and note the origin
from its outer surface in the axilla of a part of the cutaneus maximus,
and at about the same place of a thin muscle, the epitrochlearis (p.
164, and Fig. 65, _r_), _without_ determining the insertion of the
latissimus.

 9. Dissect the pectoralis group of muscles (Fig. 65, and p. 144), i.e.,
the pectoantibrachialis (Fig. 65, _m_), the pectoralis major (_l_),
pectoralis minor (_o_), and xiphihumeralis (_p_).

Determine the border of each muscle before lifting it, then work it up
at its middle, transect it, and work toward its ends, determining origin
and insertion.

Refer constantly to the skeleton.

10. Then recognize the teres major (p. 163, and Fig. 75, _d_; Fig. 77,
_c_) and the common insertion of the teres major and latissimus (Fig.
79, _d′_); find the bicipital arch (Fig. 65, _t′_) and determine its
composition (p. 166).

11 and 12. The serratus anterior and levator scapulæ (Fig. 73, _h_ and
_i_, and p. 122). In order to expose the origin of these muscles, the
external oblique muscle (Fig. 68, _p_) must be recognized, and that part
of it which has its origin from the fourth to the ninth rib should be
transected about an inch and a half from its origin and reflected.

The thoracic portion of the rectus abdominis (Fig. 73, _k_) and of the
scalenus (Fig. 73, _f_-_f‴_) should also be recognized and then raised
at their outer borders and displaced toward the median line. _No part_
of any of these muscles should be removed or cut except as directed.

The serratus anterior and levator scapulæ should be transected and
reflected to get at their origin and insertion.

B. _Muscles of the Arm_ (p. 156).--The arm is thus removed from the body
and the dissection may be continued on the separated arm.

13. The clavobrachial (Fig. 65, _k_, and p. 157). Its origin is best
seen later. Dissect it up, but do not transect it.

Search now with great care for the coracobrachialis. Consult the figures
(Fig. 79, _c_) and descriptions (p. 164), and be especially careful not
to injure the long head of the muscle and its tendon.

14. Dissect the coracobrachialis (Fig. 77, _f_). Cut and reflect it.

15. The subscapularis (Fig. 77, _a_, and p. 161). Near its glenoid end,
its glenoid and coracoid borders are separated by triangular intervals
from the adjacent muscles. Transect the muscle by a line connecting the
apices of these triangles. Carry an incision from the middle of this one
to the middle of the vertebral border of the scapula, and reflect the
muscle on both sides of this incision,--thus determining its area of
origin. Reflect the humeral end without injuring the capsule of the
joint.

16. Dissect the supraspinatus (Fig. 75, _a_, and p. 159). Cut the strong
fascia free from the border of the scapula and its spine. Then transect
the muscle and reflect it, being careful not to injure the capsule of
the joint.

17. The spinodeltoideus (Fig. 75, _e_, and p. 156). Find its two
borders, beginning with the caudal one. In freeing the very short
cranial border do not injure the acromiodeltoideus (Fig. 75, _f_).
Transect and reflect the spinodeltoid.

18. The acromiodeltoideus (p. 157, and Fig. 75, _f_). Transect and
reflect.

19. The infraspinatus (p. 160, and Fig. 75, _c_). Locate the borders in
the region of the great scapular notch. It is difficult to separate the
glenoid border from the adjacent teres minor (Fig. 80, _c_). The
separation should be begun at the humerus. Transect the muscle at the
great scapular notch and reflect. Be careful not to injure the teres
minor (Fig. 80, _c_).

20. The teres major (p. 163, and Fig. 75, _d_; Fig. 77, _c_) should be
cut near its junction with the latissimus dorsi (Fig. 77, _e_).

21. The teres minor (Fig. 80, _c_, and p. 161) need not be cut.

22. The epitrochlearis (p. 164, and Fig. 65, _r_).

23. The triceps (p. 166). (_a_) The long head of the triceps (Fig. 77,
_i_; Fig. 75, _g_). Find first its medial border and separate it from
the medial head. Note the union of its lateral surface with the dorsal
border of the lateral head by strong fascia, and then cut the fascia.

(_b_) The lateral head (Fig. 75, _h_).

(_c_) The medial head (Fig. 79, _g_, _h_, and _j_).

24. The anconeus (p. 170, and Fig. 80, _l_).

25. The brachioradialis (p. 173, and Fig. 75, _k_). Reflect it carefully
to its origin and insertion.

26. The biceps (Fig. 77, _g_, and p. 165). The capsule of the
shoulder-joint may be opened in order to expose its origin. Its
insertion cannot be seen at this stage.

27. The brachialis (Figs. 75 and 79, _i_, and p. 166). Work under it
near its union with the clavobrachial; cut it at that point and reflect
it.

28. Extensor carpi radialis longus (p. 173, and Fig. 75, _l_). Note the
oblique tendon on the radial side of the wrist near the insertion of the
brachioradialis. A second tendon passes beneath its distal border. This
tendon may be separated into a deep and superficial portion. The latter
may be traced proximad to its muscle, the extensor carpi radialis
longus.

29. Extensor carpi radialis brevis (p. 174). Its tendon is the deeper of
the two tendons seen when isolating the tendon of the extensor longus.

30. Extensor communis digitorum (p. 174, and Fig. 75, _m_).

31. Extensor lateralis digitorum (p. 175, and Fig. 75, _n_).

32. Extensor carpi ulnaris (p. 176, and Fig. 75, _o_).

33. Extensor indicis (p. 176, and Fig. 85, _c_).

34. Pronator teres (p. 179, and Fig. 77, _q_).

35. Flexor carpi radialis (p. 179, and Fig. 77, _r_). The tendon of the
flexor carpi radialis should not be traced to its insertion until the
deep muscles of the palm of the hand have been dissected.

36. Abductor brevis pollicis (p. 184, and Fig. 77, _w_).

37. Flexor carpi ulnaris (p. 180, and Fig. 77, _t_).

38. Palmaris longus (p. 179, and Fig. 77, _s_). In dissecting this
muscle be careful not to injure the part of the flexor sublimis (Fig.
77, _x_) that rises from its surface (see flexor sublimis, p. 181). Cut
the palmaris proximad of the origin of the flexor sublimis and reflect
it.

39. Flexor sublimis digitorum (p. 181 and Fig. 77, _x_). Trace one or
two of the tendons through the sheaths on the ventral surfaces of the
first phalanges. Cut and reflect the radial portion.

40. Flexor profundus digitorum (p. 181, and Fig. 77, _u_). After
recognizing the parts cut through the tendons of the first and fifth
parts and reflect them to determine their origin. Then cut through the
common tendon so as to reflect the other three parts together. Trace one
or two of the tendons to the distal end of the digit.

41. The supinator (p. 177, and Fig. 85, _b_).

42. The extensor brevis pollicis (p. 178, and Fig. 85, _a_).

43. Pronator quadratus (p. 183, and Fig. 87, _a_).

The insertion of the brachialis and clavobrachial (Fig. 87, _c_) and of
the biceps (Fig. 87, _b_) should now be examined.

There remain to be dissected the small muscles of the palm of the hand.
If these have been injured on the side dissected, the hand of the other
side may be used.

44. The lumbricals (p. 184, and Fig. 88, _f_).

45. The flexor brevis pollicis (p. 184, and Fig. 89, _a_).

46. The adductor pollicis (p. 185, and Fig. 89, _b_).

47. The abductor digiti quinti (p. 185, and Fig. 89, _i_).

48. The flexor brevis digiti quinti (p. 186, and Fig. 89, _h_). Cut and
reflect it.

49. The opponens digiti quinti (p. 186, and Fig. 89, _g_). Cut and
reflect it.

50. The interossei (p. 185, and Fig. 89).

IV. MUSCLES OF THE NECK AND THE DEEP MUSCLES OF THE HEAD.

If the superficial muscles of the head have been dissected according to
the directions above given (p. 434), the skin of the head and neck, and
the external ear, will have been removed, and the specimen is ready for
further study. The parotid and submaxillary glands (Fig. 65, 1 and 2)
should be removed if this has not been done; also the lymphatic glands
(Fig. 65, 3).

If the superficial muscles of the head have not been dissected and are
not to be, remove the skin from the side of the neck, head, and face to
the median dorsal line, removing the thin superficial muscles with the
skin. Remove also the parotid, submaxillary, and lymphatic glands (Fig.
65, 1, 2, and 3), and cut through the ear-muscles and the cartilaginous
auditory meatus (under direction) and remove the external ear. Clean
fat, connective tissue, etc., from the surface of the muscles of the
thorax, neck, and head; then dissect as follows:

 1. The sternomastoid (p. 139, and Fig. 65, _g_). Transect and reflect
it.

 2. The cleidomastoid (p. 120, and Fig. 65, _h_). This has already been
transected; examine now its origin.

Remove the large lymphatic gland beneath the sternomastoid and close to
the tympanic bulla, and clean the surface of the muscles in this region.

 3. The levator scapulæ ventralis (p. 120, and Fig. 72, _c_, _c′_,
_c″_). This has already been cut; study now its origin.

 4. The sternohyoid (p. 140, and Fig. 65, _e_). In raising it begin at
the cranial end and take care not to injure the subjacent sternothyroid
(Fig. 65, _g′_). Transect.

 5. The sternothyroid (p. 141, and Fig. 65, _g′_). Transect.

 6. The stylohyoid (p. 112, and Fig. 65, _d_). Transect.

 7. The digastric (p. 107, and Fig. 65, _b_). Transect, and reflect
completely, to the origin and insertion.

 8. The mylohyoid (p. 114, and Fig. 65, _c_). Transect and reflect.

 9. The geniohyoid (p. 113, and Fig. 67, _g_).

10. The jugulohyoid (p. 113, and Fig. 67, _b_).

(The extrinsic muscles of the tongue (p. 228, and Figs. 67 and 96) may
be dissected at this point, if desired. (_a_) The styloglossus; (_b_)
the genioglossus; (_c_) the hyoglossus. They need not be cut.)

11. The masseter (p. 108, and Fig. 65, _a_). Cut the superficial and
middle layers near their insertions by incisions parallel to the border
of the jaw. Cut the deep layer near its origin. Look for the origin of
fibres of the temporal muscle from the inner surface of the middle
layer.

12. The temporal (p. 110, and Fig. 63, _n_). Clear its outer surface
completely. Cut the temporal fascia transversely and reflect it toward
the insertion of the muscle, with the superficial portion of the muscle.
Cut through the zygomatic arch at its two ends and remove it, dissecting
the fibres of the temporal free from their origin on its inner surface.
Then examine the insertion of the temporal.

(The muscles of the pharynx (p. 232) may be dissected at this point; for
directions, see page 451.)

13. The ceratohyoid (p. 115). To uncover this, the middle constrictor of
the pharynx (Fig. 67, _j_) must be cut and reflected.

Cut the mylohyoid, geniohyoid, genioglossus, and the mucosa of the floor
of the mouth free from the mandible on both sides, so that the tongue
and the floor of the mouth may be drawn ventrad and turned out of the
way, exposing the roof of the mouth (as in Fig. 66, p. 112). Cut through
one side of the pharynx near the ventral surface and turn the tongue
toward the uncut side.

The roof of the mouth is thus exposed. Dissect next--

14. The pterygoid muscles (Fig. 66). Remove the mucosa of the roof of
the mouth, especially at the sides of the soft palate, and the two
pterygoid muscles (p. 111) are exposed. The lower jaw may be removed on
one side to get at their origin.

(The muscles of the soft palate (p. 230, and Fig. 66, _d_ and _e_), and
the superior constrictor of the pharynx (p. 233, and Fig. 66, _f_) may
be observed at this point, if desired.)

V. MUSCLES OF THE WALL OF THE THORAX AND OF THE ABDOMEN.

 1. The scalenus (p. 141, and Fig. 73, _f_-_f‴_). To trace its cervical
portion, cut the trachea and œsophagus just craniad of the first rib,
cut the pharynx and hyoid free from the ventral side of the head and
neck, and remove the pharynx, larynx, œsophagus, and trachea (these
should be preserved for future study of the larynx).

 2. The transversus costarum (p. 150, and Fig. 73, _j_).

 3. The serratus posterior superior (p. 148, and Fig. 73, _l_). Transect
this at about the middle of the muscle-bundles, and reflect it in both
directions.

 4. The serratus posterior inferior (p. 148, and Fig. 73, _n_). Transect
and reflect as in the last.

 5. The external oblique (p. 153, and Fig. 68, _p_). Transect it by an
incision parallel to its tendon of origin and about an inch from it, and
reflect in both directions.

 6. The internal oblique (p. 154, and Fig. 73, _o_). Transect and
reflect as above.

 7. The transversus (p. 155, and Fig. 69, _l_). Requires no further
dissection.

 8. The rectus abdominis (p. 155, and Fig. 73, _k_). Open its sheath by
a longitudinal incision near the linea alba.

 9. The external intercostals (p. 150, and Fig. 73, _m_; Fig. 69, _i_).
To see these, remove the origins of the levator scapulæ and serratus
anterior; also the serratus posterior superior.

10. The internal intercostals (p. 151, and Fig. 69, _k_). To uncover
these, remove the external intercostals from between two or three pairs
of ribs.

11. The transversus thoracis (p. 151). To see this muscle, which lies on
the inner surface of the thoracic wall, it is necessary to cut through
the ribs on one side one or two inches from the sternum, and open the
thorax. The muscle can then be observed directly.

(The levatores costarum will be dissected later.)

VI. MUSCLES ON THE VENTRAL SIDE OF THE VERTEBRAL COLUMN IN THE NECK
REGION (Fig. 72).

Clean the surface of these muscles, removing pharynx, larynx, œsophagus,
and trachea, if this has not been done.

 1. Longus capitis (p. 142, and Fig. 72, _a_).

 2. Longus colli (p. 144, and Fig. 72, _g′_, _g″_).

 3. Levator scapulæ ventralis (p. 120, and Fig. 72, _c′_, _c″_). Observe
its origin.

 4. Rectus capitis anterior minor (p. 143, and Fig. 72, _b_). To see
this, cut through on one side the longus capitis and one head of the
levator scapulæ ventralis, and remove the proximal portions, as in Fig.
72.

 5. Obliquus capitis superior (p. 136, and Fig. 72, _e_).

 6. Rectus capitis lateralis (p. 143, and Fig. 72, _d_).

VII. MUSCLES OF THE BACK (p. 123).

Remove what remains of the dorsal portion of the latissimus dorsi,
serratus posterior superior, and serratus posterior inferior. See that
the skin is removed completely to the dorsal middle line, or even for a
little distance over onto the other side. There is thus exposed the
lumbodorsal fascia (p. 126), covering the muscles of the back.

Cut the superficial layer of the lumbodorsal fascia (that from which the
latissimus dorsi and obliquus externus abdominis have origin) by an
incision parallel to the dorsal median line, and remove it. The muscles
of the back are thus exposed (Fig. 69). Observe in the lumbar region the
longissimus dorsi (_f_, _f′_, _f″_); in the thoracic region the
longissimus dorsi, the spinalis dorsi (_g_), and the iliocostal (_h_);
in the cervical region the splenius (Fig. 73, _b_).

 1. The longissimus dorsi (p. 126, and Fig. 69, _f_, _f′_, _f″_). Notice
in the lumbar region the strong deep layer of the lumbodorsal fascia, by
which this muscle is covered, and from the under side of which many of
the fibres of the muscle take origin. Cut this fascia by an incision
parallel to the dorsal median line and about two centimeters from it,
from the level of the crest of the ilium as far craniad as the fascia
can be cut without cutting into the muscle-fibres (usually to about the
level of the last rib). Reflect the medial division of the fascia to the
middle line. Reflect the lateral division of the fascia until it passes
into the muscle and cannot be farther reflected.

Observe then in the lumbar region the medial (Fig. 70, _a_) and lateral
(Fig. 70, _b_) divisions of the longissimus dorsi, and the portion
(_b′_) of the lateral division taking origin from the lumbodorsal fascia
(_c_). Dissect apart some of the muscle-fibres of the longissimus and
observe their origin and insertion.

Trace the longissimus dorsi into the thoracic and cervical regions (Fig.
69, _f′_, _f″_) noting the separation off from it on the dorsal side of
the spinalis dorsi (Fig. 69, _g_); on the ventral side of the iliocostal
(Fig. 69, _h_).

 2. The extensor caudæ lateralis (p. 137, and Fig. 70, _f_). Uncover
this by cutting the lumbodorsal fascia over the sacral region.

 3. The iliocostalis (p. 128, and Fig. 69, _h_). Uncover this
completely; note its connection with the longissimus dorsi at the caudal
end. Dissect apart some of its muscle-bundles, to see origin and
insertion.

 4. The splenius (p. 131, and Fig. 73, _b_). Transect this by an
incision beginning at its lateral border about four centimeters from the
cranial end of the muscle and extending obliquely craniodorsad to the
craniomedial angle of the muscle. Be careful not to injure the
longissimus capitis (Fig. 73, _g_).

 5. The longissimus capitis (p. 131, and Fig. 73, _g_). Transect.

 6. The spinalis dorsi (p. 129, and Fig. 69, _g_). Separate some of its
muscle-fibre bundles and trace to origin and insertion.

 7. The biventer cervicis (p. 132, and Fig. 69, _a_). Raise its lateral
border, turning it toward the middle line, and transect it near its
caudal end.

 8. The complexus (p. 133, and Fig. 69, _b_). Raise its medial border,
and transect it near its cranial end.

 9. The longus atlantis (p. 134, and Fig. 71, _f_).

10. The multifidus spinæ (p. 130, and Fig. 70, _d_). Remove a part of
the longissimus dorsi in the lumbar region, and trace the course of the
fibres of the multifidus spinæ. (If desired the entire longissimus may
be removed and the multifidus spinæ completely uncovered.)

11. The extensor caudæ medialis (p. 136, and Fig. 70, _e_).

12. The semispinalis cervicis (p. 133, and Fig. 71, _c_). Dissect apart
some of its fibre-bundles to see origin and insertion.

13. The interspinales and intertransversarii (p. 131) may be seen in the
region from which the longissimus dorsi was removed, by removing the
bundles of the multifidus spinæ.

14. The rectus capitis posterior major (p. 134, and Fig. 71, _a_).
Transect.

15. The obliquus superior (p. 136, and Fig. 71, _e_).

16. The obliquus capitis inferior (p. 136, and Fig. 71, _b_).

17. The rectus capitis posterior medius (p. 135). Transect.

18. The rectus capitis posterior minor (p. 135).

19. The levatores costarum (p. 150). Remove in a part of the thoracic
region a portion of the iliocostal and longissimus dorsi, so as to
expose the dorsal ends of the ribs. The levatores costarum will be seen
as but slightly separated bundles continuous with the external
intercostals.

VIII. MUSCLES OF THE HIND LIMBS (p. 186).

Remove the skin and superficial fascia from the lateral surface of the
thigh. Examine the _fascia lata_ (p. 186, and Fig. 68, _z_). Dissect:

 1. The biceps femoris (p. 194, and Fig. 68, _t_). Work under its
cranial and caudal borders. Find the tenuissimus (Fig. 90, _g_) passing
obliquely beneath it and reaching its caudal border in its distal half.
Transect the biceps without injuring the tenuissimus, and reflect its
halves.

 2. The tenuissimus (p. 195, and Fig. 90, _g_). Transect.

 3. The caudofemoralis (p. 195, and Fig. 68, _s_). Transect.

 4. The gluteus maximus (p. 187). Transect.

 5. The sartorius (p. 197, and Fig. 68, _q_; Fig. 91, _a_). Transect.

 6. The tensor fasciæ latæ (p. 187, and Fig. 68, _r_). Cut the fascia
lata along the distal end of the muscle-fibres and reflect the muscle.

 7. The gluteus medius (p. 188, and Fig. 90, _b_). Work under it
carefully, separating it from underlying muscles; cut it close to its
tendon of insertion, and reflect it.

 8. The pyriformis (p. 188, and Fig. 163, 7, p. 401). Cut and reflect
it.

 9. The gemellus superior (p. 189, and Fig. 163, 6). This and the next
muscle will sometimes be found to be completely united. Transect.

10. The gluteus minimus (p. 189, and Fig. 163, 5). Transect.

11. The obturator internus (p. 192, and Fig. 90, _e_). Cut it at the
dorsal border of the ischium in order to reflect it. The whole origin
cannot be seen at this stage.

12. The gemellus inferior (p. 190).

13. The gracilis (p. 198, and Fig. 91, _b_). Transect.

14. The semitendinosus (p. 196, and Figs. 90 and 91, _j_; Fig. 92, _i_).
Transect.

15. The semimembranosus (p. 196, and Figs. 90 and 91, _i_; Fig. 92, _h_,
_h′_). Transect.

16. The adductor femoris (p. 198, and Figs. 90 and 91, _h_; Fig. 92,
_g_). Transect.

17. The quadratus femoris (p. 191, and Fig. 90, _f_). Transect.

18. The obturator externus (p. 191).

19. The adductor longus (p. 199, and Fig. 92, _f_). This and the
following will sometimes be found to be almost completely united.
Transect.

20. The pectineus (p. 200, and Fig. 92, _e_). Transect.

21. The iliopsoas (p. 193, and Fig. 91, _c_; Fig. 92, _d_). Only its
distal part, near the insertion, can be seen at present.

22. The capsularis (p. 190). Transect.

23. The quadriceps femoris (p. 201). Isolate the rectus femoris (Fig.
92, _b_) as far as its junction with the vastus lateralis; cut it at
this point and reflect its proximal portion. Turn aside the distal end
and find beneath it the transverse aponeurosis between the vastus
medialis and the vastus lateralis, and covering the vastus intermedius.
The vastus lateralis (Fig. 90, _d_) may be cut near the middle and
dissected up from its origin in both directions; the vastus intermedius
is thus exposed. The vastus medialis (Fig. 92, _c_) and the vastus
intermedius need not be cut.

24. The gastrocnemius (p. 203, and Fig. 90, _m_; Fig. 91, _k_). It may
be raised cautiously near its middle and divided. Care should be taken
not to divide the underlying plantaris (Fig. 90, _l_). After noting the
connection of the outer head with the plantaris, the latter may be
divided and reflected, together with the outer head.

25. The plantaris (p. 205, and Figs. 90 and 91, _l_).

26. The flexor brevis digitorum (p. 212). In tracing its tendon note the
three branches of the common plantar ligament which emerges from between
the second and third tendons. The outer branch is inserted into the
fascia covering the base of the fifth digit, while the other two spread
out into the bilobed pad of the sole.

27. The soleus (p. 205, and Fig. 90, _o_). Cut and reflect.

28. The popliteus (p. 206, and Fig. 92, _k_). Cut very near the origin
and reflect.

The three following deep muscles on the ventral surface of the shank are
covered by the deep crural fascia (p. 206) which separates them from the
overlying muscles. It should be removed.

29. The flexor longus hallucis (p. 207, and Fig. 91, _m_). Divide the
muscle at its junction with the tendon. Open the canals on the
astragalus and calcaneus and reflect the tendon, cutting the tendon of
the flexor longus digitorum near its insertion and dividing at the
middle the quadratus plantæ (p. 213) which may be found inserted into
its ventral surface.

30. Flexor longus digitorum (p. 208, and Fig. 91, _n_). This may be
divided very near its origin.

31. Tibialis posterior (p. 208, and Fig. 91, _o_). This may be divided
near its tendon.

32. Peroneus longus (p. 209, and Fig. 90, _q_). The overlying tendons
may be cut in tracing its insertion.

33. Peroneus brevis (p. 210, and Fig. 90, _s_).

34. Peroneus tertius (p. 210, and Fig. 90, _r_).

35. Extensor longus digitorum (p. 210, and Fig. 90, _p_).

36. Tibialis anterior (p. 211, and Fig. 90, _n_).

37. The extensor brevis digitorum (p. 212, and Fig. 90, _u_).

38. The quadratus plantæ (p. 213). It was cut in dissecting the flexor
longus hallucis.

39. The lumbricales (p. 213).

40. The interossei (with the muscles of the fifth digit) (p. 214).

41. The tarsal muscles (p. 215). The overlying ligaments must be removed
in order to expose the scaphocuneiform.

IX. THE DIAPHRAGM AND THE MUSCLES ON THE VENTRAL SIDE OF THE VERTEBRAL
COLUMN IN THE LUMBAR AND PELVIC REGIONS.

Remove the ventral and lateral walls of the thorax completely, as far
back as the diaphragm,--leaving only a ring attached to the margin of
the diaphragm. Remove the abdominal walls in the same way, as far back
as the pubis, leaving the diaphragm in position. Remove the thoracic
viscera (the heart and lungs may be preserved for future study). Remove
also the abdominal viscera as far back as the beginning of the pelvis,
cutting the large intestine where it passes into the pelvis. The dorsal
wall of the abdominal cavity should be cleared of fat, blood-vessels,
etc., without injury to the crura of the diaphragm.

 1. The diaphragm (p. 151, and Fig. 74). Study by transmitted light, to
see the tendons, etc.

 2. The psoas minor (p. 139, and Fig. 162, 9, p. 398). Find its tendon
and separate it from the iliopsoas (Fig. 162, 8) as far craniad as this
can be done without tearing the fibres.

 3. The iliopsoas (p. 193, and Fig. 162, 8). Find both portions; isolate
them as far as it can be done.

 4. The quadratus lumborum (p. 139). Free the lateral edge of the
iliopsoas from the abdominal wall and turn the whole muscle mediad as
far as possible. The bundles of the quadratus lumborum will be found
beneath it, against the transverse processes of the lumbar vertebræ.

With a heavy cartilage-knife separate the two innominate bones along the
pelvic symphysis. This is easily done if the knife is inserted exactly
into the line of junction of the two bones. Divaricate the edges some
distance, so as to make a ventral opening into the pelvic cavity. If
necessary, part of the innominate bone of one side may be removed to
make the opening larger.

Find the thin sheet of fibres forming the levator ani muscle (Fig. 162,
11) at the side of the rectum, attached to the edge of the symphysis.
Carefully free the rectum and urogenital organs from this and remove
them as far as the anus, leaving the levator ani intact.

 5. The iliocaudalis (p. 137, and Fig. 162, 11′).

 6. The levator ani (p. 269, and Fig. 162, 11).

Remove with great care the levator ani and iliocaudalis of one side, by
cutting first the attachment to the symphysis and the ilium, turning the
muscle mediad, then cutting the attachment to the tail. There are thus
exposed on the lateral wall of the thorax the medial surface of the
obturator internus, craniad of it the pyriformis, caudad of it the
quadratus femoris. Dorsad of these is the abductor caudæ internus.

 7. The abductor caudæ internus (p. 137).

On the ventral surface of the tail are exposed the following:

 8. The flexor caudæ longus (p. 138, and Fig. 162, 12).

 9. The flexor caudæ brevis (p. 138, and Fig. 162, 13).

X. MUSCLES OF THE TAIL (p. 136).

By removing the skin of the tail, all the muscles of the tail are now
easily seen.

 1, 2, 3, 4, 5--see 5, 6, 7, 8, 9, above (IX).

 6. The abductor caudæ externus (p. 137, and Fig. 113, _b_; Fig. 70,
_g_).

 7. The extensor caudæ lateralis (p. 137, and Fig. 70, _f_).

 8. The extensor caudæ medialis (p. 136, and Fig. 70, _e_).

THE VISCERA.

Kill the specimen with chloroform and inject with the five per cent.
formalin, or the mixture of formalin and glycerine, as for the muscles.
(It is an advantage if the preliminary examination of the viscera can be
done in a perfectly fresh, uninjected specimen; such a specimen can be
kept but a day or two, however. After one day’s examination the skin may
be removed and the specimen placed in two per cent. formalin; it will
usually be fairly well preserved by this, though the formalin is too
strong to make the later dissection pleasant. The specimen cannot be
preserved in this manner unless the skin is removed, and a sufficient
quantity of formalin used.)

PRELIMINARY EXAMINATION OF THE VISCERA.

(In this preliminary examination the descriptions in the text need not
be read, except when this is specially directed.)

Wet the hair along a line from the symphysis of the jaw to the pubis.
Part it and make a longitudinal incision through the skin along the
line. Make a transverse incision of the skin five centimeters caudad of
the xiphoid process and reflect the flaps. Incise the body wall from the
last rib to the pelvis along the same line as above and also
transversely. Reflect the flaps without injuring the ligaments of the
bladder. Make an incision through the pectoral muscles between the first
rib and the ventral attachment of the diaphragm and about one centimeter
from the median line. Make a second incision of the muscles from the
cranial end of the first incision along the angles of the ribs to near
the dorsolateral attachment of the diaphragm. Cut the ribs and thoracic
wall along these incisions with strong scissors; connect the two
incisions at their caudal ends, and remove the lateral thoracic wall
thus circumscribed. Note the thoracic and abdominal cavities, separated
by the diaphragm.

Note the following viscera in their fresh condition:

A. In the abdominal cavity (without injuring anything)

 1. The liver, dark red and lobed, in the cranial part of the cavity,
lying against the diaphragm.

 2. The gall-bladder partly imbedded in the right median lobe.

 3. Displacing the liver craniad, the stomach is seen dorsad of its left
lobe. It may extend dorsad of the right lobe, its size depending on the
degree of distension.

 4. The duodenum or first part of the small intestine leaves the stomach
at its right side craniad and makes a U bend, the head of which is
directed caudad; it then turns toward the middle line dorsad of the
remaining part of the small intestine.

 5. The great omentum is a thin fold of peritoneum with many bands of
fat. It passes like a curtain from the great curvature of the stomach
ventrad of the coils of the small intestine (ileum). It is tucked
beneath the mass of coils at the sides and caudally, and folds of it
extend between the individual coils. Turn it craniad and note--

 6. The numerous coils of the third part of the small intestine or
ileum. Turn these to one side and note--

 7. The connection of the ileum with the duodenum across the middle
line. An indefinite part of the intestine between the ileum and duodenum
is called the jejunum, because in man it is found empty after death.

 8. The passage of the ileum into the side of the large intestine which
begins on the right side just caudad of the loops of the duodenum. The
first part of the large intestine is the colon. It may be traced first
toward the head (ascending colon), then sinistro-caudad (transverse
colon) and then caudad (descending colon). The descending colon returns
to the middle line and the large intestine then continues to the anus as
the rectum.

The blind pouch of the colon which lies caudad of the opening of the
ileum is the cæcum.

 9. Turn the duodenum toward the left and note the pancreas, a light
red, elongated organ which stretches along the greater curvature of the
stomach and thence between the two lines of the duodenal U to its
bottom.

10. The spleen, parallel to the gastric portion of the pancreas. It is
deep red (darker than the pancreas and not so brown as the liver) and is
held against the great curvature of the stomach by a part of the great
omentum.

11. The kidneys, close against the dorsal body wall and in contact with
the caudal part of the liver.

12. The bladder, in the median line at the caudal end of the cavity,
held in place by the suspensory ligament, which passes to the midventral
line, and by the lateral ligaments.

13. The mesenteric glands, large grayish-red glands one to four
centimeters long, more numerous in the mesocolon.

14. In the female, lying against the ventral surface of the rectum, the
uterus. It divides into two horns which diverge. Near the end of each
horn the ovary.

15. The peritoneum. Study and understand the description of it (p. 218).
Dissect some of it free from the body wall. (Trace the folds by aid of a
diagram and model.)

B. In the thoracic cavity:

 1. The lungs. Each is divided into lobes, three on the left, four on
the right. The caudal right lobe pushes the mediastium toward the left
and thus lies in a pocket dorsocaudad of the heart and dorsad of the
vena cava inferior.

 2. The pleuræ. Each pleura is a membrane like the peritoneum. It covers
the diaphragm and the thoracic walls and is reflected onto the lungs.
Hence it is divided into costal and pulmonary portions. Read the
description (p. 217) and trace their connection. Each pleura forms a
closed sac.

 3. The mediastinal septum or median vertical portion formed by the
apposition of the medial walls of the two pleural sacs. It divides the
thorax into halves.

 4. In the mediastinum or space between the halves of the mediastinal
septum are seen--

_a._ Ventrally (i.e., in the anterior mediastinum), blood-vessels and
fat, and craniad the pink thymus gland. Read the description of the
thymus (p. 254, and Fig. 107).

_b._ Dorsally (i.e., in the posterior mediastinum) the trachea (best
seen craniad), the œsophagus (best seen caudad), and the aorta.

_c._ In the middle (reckoning in a dorsoventral line) (i.e., in the
middle mediastinum) the heart, with the inferior vena cava approaching
it from the rear. Prick into the mediastinum and inflate it. Remove the
thoracic wall opposite the one already removed, so as to stretch the
mediastinum and show it more clearly. Expose the trachea beneath the
caudal end of the sternomastoidei. Note the thyroid gland (Fig. 96, 6,
p. 229). Insert a blowpipe without injury to the thyroid, and inflate
the lungs. Cut the sternum at its caudal end and turn it craniad,
cutting the mediastinal septum and noting its double character.

Dissect the mediastinal septum from the thymus so as to expose this
organ.

_d._ The pericardium, a relatively thick-walled sac, within which the
heart lies. The pericardium is covered by the mediastinal septum on each
side, but not dorsally and ventrally. Dissect the mediastinal septum
from the pericardium. Prick and inflate the pericardium. Open it and
expose the heart.

DISSECTION OF THE ALIMENTARY CANAL.

Study and verify the descriptions of the organs as they are dissected.

I. Salivary glands (p. 223).

 1. Keep the mouth open by a cork between the teeth. Find the papillæ
upon which open the sublingual and submaxillary ducts (pp. 223 and 224);
remove the mucosa and enlarge the opening and insert a black bristle
into either duct. Trace the duct by the bristle as far as possible on
the floor of the mouth.

 2. Find the white ridge formed on the cheek by the parotid duct (p.
223). It is opposite the molar tooth, and at its cranial end the opening
of the duct is seen. Enlarge the opening and insert a black bristle as
far as possible.

 3. Remove the skin and the skin-muscles from the side of the face,
beginning at the caudal end and working craniad. At the cranial border
of the carotid on the ventral side look carefully for the parotid duct
with the bristle in it. The duct is then easily traced by the removal of
the skin and muscles. Study the parotid gland (Fig. 131, 10, p. 322).

 4. Remove the facial vein (Fig. 131, _b_ and _c_) and lymphatic gland
(Fig. 131, 12) covering the submaxillary gland (Fig. 131, 11) and clean
its outer surface. Raise it and find the submaxillary duct leaving its
inner surface. Reflect the digastric and mylohyoid muscles and trace the
duct to the oral mucosa. The remainder of its course is shown by the
bristle on the inside of the mouth.

 5. The sublingual gland is uncovered in dissecting the submaxillary.
Its duct is seen by the side of the submaxillary. It may be pricked near
the gland and a bristle passed to its opening.

 6. The infraorbital gland. Expose it by removal of the zygomatic arch
and masseter muscle. Find its duct by dissecting apart the lobules at
its ventral end. Prick the duct and insert a bristle to find its inner
opening.

 7. The molar gland. Find it by raising the orbicularis oris of the
lower lip. By raising its ventral border and dissecting between it and
the mucosa the ducts may be found and perhaps pricked and bristles
inserted.

II. The mouth-cavity. Study the general description (p. 221); the lips
and the cheek. Then remove the masseter muscle and the caudal part of
the zygoma. Cut through the mandible between the first premolar and the
canine tooth. Then disarticulate the mandible, cut the cheek and also
the mylohyoid muscle and oral mucosa parallel to the medial border of
the mandible, and remove the mandible with the parts thus left attached
to it. The organs in the mouth-cavity are thus left exposed and should
be studied. To demonstrate the incisive ducts (p. 222) pass a bristle
into them.

The teeth (p. 224). These should be studied on a skull in which the
roots of the teeth have been laid bare by means of the bone-forceps, as
in Figs. 93 and 94.

The tongue (p. 226, and Fig. 95). Study its dorsal surface, the papillæ,
etc. Then dissect its _muscles_ (p. 228) from the ventral side. The
stylohyoid, digastric, and mylohyoid muscles must be removed. Then
dissect (_a_) the styloglossus (Fig. 96, _e_), (_b_) the genioglossus
(Fig. 96, _f_), (_c_) the hyoglossus (Fig. 96, _h_). Make a transverse
section of the tongue to see the intrinsic muscle-fibres.

III. The thyroid gland (p. 254, and Fig. 96, 6). Clean the sternomastoid
muscles. Cut their interdigitating portions along the median line and
reflect them. Find the lateral lobe of the thyroid gland beneath the
lateral borders of the sternohyoid muscles. Dissect it, being careful
not to destroy the delicate isthmus.

IV. The pharynx (p. 231). Remove the large lymphatic gland between the
atlantal transverse process and the larynx. Clean the outer surface of
the pharynx. Dissect the muscles of the pharynx (p. 232) as follows:

  (_a_) The inferior constrictor (Fig. 96, _k_).

  (_b_) The middle constrictor (Fig. 96, _j_).

  (_c_) The glossopharyngeus (Fig. 96, _i_).

  (_d_) The stylopharyngeus (Fig. 96, _l_).

The superior constrictor cannot well be seen at this point; it will be
examined later.

Disarticulate the cranial cornu of the hyoid from the bulla tympani and
make an incision the length of the lateral wall of the pharynx so as to
expose its cavity; study. Examine its opening into the mouth-cavity and
study the general description (p. 231). Find and study the soft palate
(p. 230). Dissect the tensor and levator palatini muscles (p. 230, and
Fig. 66, _d_ and _e_, p. 112), using, if necessary, the specimen on
which the other muscles were dissected. Then slit the soft palate
lengthwise at one side of the median line to expose the nasopharynx (p.
231). Bring the choanæ into view by use of a bit of mirror-glass. Pass a
bristle into the nares and out at the choanæ. Pass a bristle through the
Eustachian tube into the middle ear.

V. Œsophagus (p. 234). After completing the study of the pharynx, leave
the larynx and lungs in position and by displacing them toward the right
follow the œsophagus to its termination. Open it to see the folds of the
mucosa.

VI. Cut through the duodenum at its distal end and through the duodenal
mesentery so as to separate the stomach and duodenum, with the liver,
pancreas, and spleen, from the remainder of the alimentary canal. Float
the parts in a dish of water.

VII. Study the stomach (p. 234, and Fig. 97). Cut out the ventral wall
of the stomach and wash it out, so as to study its cavity, and then
continue the cut so as to expose the pyloric valve (p. 235).

VIII. Study the duodenum (p. 236). Cut away the ventral walls of the
duodenum far enough to expose the ampulla of Vater.

IX. Study the liver (p. 239, and Figs. 100 and 101). Expose the hepatic
duct of the left lateral lobe near its entrance into the lobe, and
follow it so as to expose it fully. If necessary, prick it and inflate
with blowpipe in order to follow it. Then expose the cystic duct and
other hepatic ducts and follow them to or from the common bile-duct.
Trace the latter to the duodenum. If the air does not enter any duct
readily, it may be made to do so by manipulating the duct so as to break
up the precipitated bile which obstructs it.

X. Study the pancreas (p. 241, and Fig. 102). Expose the pancreatic duct
near its entrance into the ampulla of Vater, by removing the peritoneum
from the pancreas just caudad of the end of the common bile-duct, and by
dissecting apart the pancreatic lobules until the duct appears. (If
possible, expose also the accessory duct in the same way on the ventral
side of the pancreas, two centimeters caudoventrad of the ampulla of
Vater. Prick and inflate. Trace its connection with the main duct. To
demonstrate its opening pass a bristle through an opening in it into the
duodenum.) (The pancreatic duct may be injected, if desired.)

XI. The ventral wall of the duodenum should now be removed. Cut out a
small piece, clean its mucosa with a fine brush and examine the villi
with a lens. Demonstrate the coats of the duodenal wall by stripping
them off with forceps.

XII. The ampulla of Vater (p. 236). Pass bristles through openings in
the common bile-duct and pancreatic duct into the duodenum through the
ampulla. Slice away the duodenal wall parallel to the bristles until the
bristles are exposed.

XIII. The spleen (p. 242, and Fig. 102).

XIV. Cut the mesentery from the small intestine and colon and slit them
both lengthwise, but do not destroy the ileocolic valve. Wash and brush
the mucous membrane clean and study the villi, solitary glands, and
Peyer’s patches. Study the ileocolic valve (Fig. 99) and open it to
study its inner surface.

DISSECTION OF THE ORGANS OF RESPIRATION.

I. The nasal cavity (p. 243). Review the description of the nasal cavity
given under the Bones (p. 59). Study the cartilaginous framework that
supports the external nose (p. 243); make a cross-section of the
framework near the end of the nose and verify the description (p. 244,
and Fig. 103). Without injuring the larynx or tongue saw through the
head in a vertical plane and a little to one side of the median line.
(If desired, the brain may first be removed from the specimen and
preserved for future study. For directions, see page 462. The removal of
the brain does not injure the head for the study of the nasal cavity;
the skull may be sawn lengthwise in the same way as before.) Wash out
the cut surfaces before examining. Find the ventral conchæ (p. 40), the
labyrinths of the ethmoid (p. 43), the inferior meatus of the nose (p.
243), and by bristles the lachrymal duct or canal (p. 245). The
lachrymal duct is conveniently found by passing bristles into the
openings of the lachrymal canals. One of these is to be found on the
border of each eyelid, two or three millimeters from the inner angle of
the eye (see p. 410).

Cut the œsophagus and trachea at the point where the blowpipe was
inserted into the trachea. Separate the tongue, hyoid, larynx,
œsophagus, and first part of the trachea from the adjacent parts and
remove them.

II. The larynx (p. 246). (1) Read the description, studying the
cartilages (p. 247) on a preparation (Fig. 104). Then very carefully
remove the pharynx and its constrictor muscles, the sternothyroid and
remains of sternohyoid muscles, and (2) dissect the muscles of the
larynx (p. 249, and Fig. 105). Dissect all those of one side first. The
mucosa lining the vestibule and middle portions of the laryngeal cavity
must be removed. After studying the muscles, remove the muscles and
entire mucosa by scraping carefully with a dull but smooth scalpel, and
study the cartilages (Fig. 104).

III. The trachea and lungs (p. 251, and Fig. 106). The distal end of the
trachea and lungs may now be removed with the heart from the body. The
lungs may be inflated with the bellows. The bronchi should then be
exposed, cleaned, and followed as far as possible into the lungs. The
heart should be preserved for future study.

DISSECTION OF THE UROGENITAL ORGANS.

A. _Excretory Organs._

 1. Expose the kidney (p. 255, and Fig. 108) by removal of the
peritoneum and the surrounding fat, taking care not to open the capsule
of the kidney. In removing the fat from the cranial end do not injure
the suprarenal body (p. 257), which should be studied.

 2. Open the capsule of the kidney and slice away its ventral wall to
expose the sinus. After dissecting the contents of the sinus open the
pelvis and study the papilla. Pass a bristle from the pelvis into the
ureter.

 3. Make a median section of the kidney parallel to its ventral surface
and study structure (Fig. 109).

 4. Trace the ureter to the bladder, being careful not to injure the vas
deferens. Study the bladder and its ligaments, structure of its wall,
etc. Pass a bristle through the ureter into it and then open it to see
the openings of the ureter. Trace the neck of the bladder to the pubis.

B. _Male Genital Organs._

 1. Study the external genital organs (p. 257).

 2. Carefully remove the integument about the anus and expose the
external sphincter ani muscle (p. 268, and Fig. 113, _i_). Trace it to
its origin. Remove the integument of the scrotum and dissect the
intercolumnar fascia, the levator scroti muscle (p. 271, and Fig. 113,
_j_), the tunica vaginalis communis, and propria (p. 258).

 3. The testis; the epididymis with great care, especially in uncovering
the vasa efferentia; the vas deferens and spermatic cord (p. 259, and
Figs. 110 and 111).

 4. Follow the cord to the external inguinal ring (p. 259) and expose
the ring. Dissect off in order from the inguinal canal: (_a_) The
external oblique muscle; (_b_) the internal oblique muscle; (_c_) the
transversus. In this way the cord is followed with its tunica communis
and tunica propria to the internal inguinal ring.

 5. Trace the vas deferens (p. 260, and Fig. 111) within the abdominal
cavity as far as it can be seen dorsad of the neck of the bladder.

 6. The penis (p. 262, and Figs. 111 and 113). Cut the skin along the
dorsum of the penis and reflect. Dissect the ligamentum suspensorium
penis. Then introduce a bristle into the urethra and remove the
integument from the whole penis and identify the corpora cavernosa and
corpus spongiosum and the urethra.

 7. Remove the fat at the side of the rectum and find the levator ani
muscle (p. 269, and Fig. 162, 11). Transect and reflect it. The internal
sphincter ani (p. 269, and Fig. 113, _h_). Find the external opening of
the anal gland (p. 239); slit and examine it.

 8. Dissect the ischiocavernosus (p. 269) and bulbocavernosus (p. 271)
muscles (Fig. 113), and find the bulbus of the corpus cavernosum beneath
the former. Cut it free from the ischial ramus.

 9. Clean the muscles from the pelvis on the side from which the crus
penis is removed, and remove with bone forceps the body of the pubis and
the ramus of the ischium. Then trace the neck of the bladder to its
junction with the vasa deferentia, and the urethra from that point to
the external opening (Fig. 111). Study the compressor urethræ muscle (p.
271, and Fig. 113, _n_). Find Cowper’s glands (p. 261) and the prostate
gland (Fig. 113). Dissect the other muscles of the urogenital organs
(pp. 268 to 273, and Fig. 113).

10. Slit the urethra on one side throughout its length and find the veru
montanum (p. 261); the openings of the vasa deferentia (p. 261), by
bristles passed into the urethra from them; the openings of the prostate
gland and the openings of Cowper’s glands.

11. Study the structure of the penis (p. 262) by making a cross-section,
and that of the glans by making a longitudinal section. Note, if
possible, the os penis.

C. _Female Urogenital Organs_ (p. 263, and Fig. 112). The kidney and its
ducts and the bladder are like those of the male (p. 255), except the
neck of the bladder, which will be seen in dissecting the uterus and
vagina.

_a._ Without cutting anything examine--

 1. The ovaries (p. 264); the ligaments of the ovary (p. 264, and Fig.
112).

 2. The uterine tube. Its ostium (p. 264).

 3. The body of the uterus (p. 266) as far as exposed.

 4. The cornu of the uterus.

 5. The broad and round ligaments of the uterus (p. 266).

 6. Slit open one Fallopian tube, cornu, and body of the uterus as far
as the junction of the divisions of the body of the uterus.

_b._ Remove the ventral wall of the pelvis on one side only and find the
vagina and urogenital sinus (p. 267). The levator ani muscle (p. 269,
and Fig. 162, 11) must be cut and reflected.

 1. Note the constrictor vestibuli, caudovaginalis, and urethralis
muscles (p. 272, and Fig. 114).

 2. Introduce a probe from the uterus into the vagina and feel with the
finger for the hard cervix uteri (p. 266). Then open the vagina on the
side, but do not cut the os uteri (p. 266).

 3. Examine the cervix uteri and os uteri (p. 266).

 4. Introduce a probe through the neck of the bladder and note its
emergence into the urogenital sinus.

 5. Find the end of the clitoris (p. 267), and its prepuce, and then
dissect the integument carefully from about the external opening of the
urogenital sinus and note an external sphincter of the sinus (M. levator
vulvæ) (p. 272, and Fig. 114), equivalent to the levator scroti in the
male and continuous with the external sphincter ani.

 6. Find (if possible) the corpora cavernosa of the clitoris (p. 267)
and the ischiocavernosi muscles (p. 269).

DISSECTION OF THE CIRCULATORY SYSTEM.

I. THE HEART (p. 274, and Figs. 115-117).

Use the heart from the specimen dissected for the muscles, or from the
specimen on which the viscera were studied.

 1. Study the outside (p. 275, and Figs. 115 and 116), and learn to
recognize all parts. Find the pulmonary veins (p. 275, and Fig. 116,
_g_, _h_, _i_) and cut them, thus separating the heart from the lungs.

 2. The Pericardium (p. 279). In a specimen the thoracic contents of
which have not been injured, dissect the mediastinal septum from the
pericardial sac and remove fat about the great blood-vessels so as to
expose them all fully. Study their relations. Prick and inflate the
pericardium. Slit it lengthwise over the ventricles and reflect it so as
to expose its contents. Study the attachment of serous and fibrous
layers to the heart and their relation to one another.

 3. In dissecting the heart follow the course of the blood, studying
each cavity with the aid of the descriptions (pp. 275-279) as you
proceed. Dissect as follows:

_a._ Remove the dorsal wall of the right auricle (p. 275) and of its
appendage except that part of it to which the venæ cavæ are attached.

_b._ Introduce the probe from the right auricle into the right
ventricle, and feel with the probe the line along which the ventricular
wall joins the septum. Cut along this line so as to turn back the
ventricular wall as a flap, which remains attached at the base of the
ventricle.

_c._ Introduce a probe through the conus arteriosus into the pulmonary
artery and cut along the probe.

_d._ Remove the dorsal wall of the left auricle and its appendage, _but
do not_ remove that part to which the pulmonary veins are attached.

_e._ Make a longitudinal incision beginning at the apex and divaricate
the lips of the cut as you pass toward the base, thus avoiding injury to
the lateral flap of the bicuspid valve. Without injury to the flap or
the columnæ carneæ, remove the heart-wall at the sides of this incision
near the base of the ventricle, as much as necessary to expose the
cavity.

_f._ Pass a probe into the aorta. Introduce scissors behind the septal
flap of the bicuspid valve and slit the aorta without injury to the
bicuspid valve.

II. DISSECTION OF THE BLOOD-VESSELS.

_Preparation and Injection._--A new specimen must be prepared for the
dissection of the blood-vessels. The same specimen may be used, if
necessary, for the dissection of the peripheral nervous system,--one
side being used for the blood-vessels, the other for the nerves,--but it
is much better to use separate specimens for the two systems.

Inject the femoral artery of the specimen with either five per cent.
formalin, or with the mixture of five per cent. formalin and glycerine,
exactly as for the muscles. Then, without removing the canula or
waiting, inject the artery with red starch. This is prepared as follows:

Mix together equal volumes of vermilion (or red lead), glycerine, and
five per cent. formalin. Grind these together in a mortar, so as to
destroy the lumps; strain the resulting mixture through fine muslin.
This color mixture can be preserved in a closed bottle till it is to be
used. Then mix together one volume of dry starch, one and one-fourth
volumes of five per cent. formalin, and one-fourth volume of the color
mixture. See that no lumps are present.

Inject the above red starch mass into the femoral artery. It will drive
into the veins the formalin already injected, and the arteries will be
filled with the red starch.

The veins need not be injected, as they will be found to be filled with
the formalin mixture, colored by the blood, so that they can be traced
without great difficulty.

_Dissection of Blood-vessels._--In general the arteries and veins will
be traced together. It is an excellent plan to make a sketch of each
vessel as it is dissected, showing its origin, branches, and name. This
will be a great aid to the memory and will be of much assistance in
reviewing the vessels. The sketches can later be combined into a
well-ordered drawing. The description of each vessel must of course be
studied as the vessel is dissected.

In tracing blood-vessels _do not_ grasp them between the forceps-blades,
but handle them by taking hold with the forceps of the connective-tissue
coats of the vessels. _Do not_ use the scalpel, but _pull_ away the
connective tissue and fat with fine forceps, using two pairs of forceps
or one forceps and the tracer.

Variations are especially common in the blood-vessels, and the student
must not be surprised to find considerable deviations from the
conditions described and figured in the text. These variations usually
present nothing new in principle and are easily understood by comparing
them with the structures described.

_Directions for Dissecting the Blood-vessels._--Make a median
longitudinal incision through the skin from the symphysis of the jaw to
the caudal end of the xiphoid process. About three or four centimeters
caudad of the cranial end of the sternum make an incision at nearly
right angles to this, passing from the first incision on the ventral
side of the left arm about to the elbow. Reflect the flaps of skin, so
as to uncover the left side of the thorax and the under surface of the
arm, exposing the pectoral muscles. Isolate and transect the pectoral
muscles one at a time, cutting each near its thoracic attachment. (The
muscles (p. 145) should be reviewed at the same time.) In this way the
nerves and blood-vessels of the axilla are exposed (Fig. 122, p. 295).

Find the axillary artery and vein (Fig. 122, _f_ and _g_) emerging from
the thorax just craniad of the first rib, along with the nerves of the
brachial plexus. Remove connective tissue, etc., so that the vessels and
nerves are well isolated as they pass out of the thorax. Take great
pains not to puncture the vessels, particularly the veins.

Then remove the left side of the thorax by cutting through the first rib
near its sternal end and then near its dorsal end, without injury to the
vessels and nerves, cut the other ribs in the same way, and take out the
thoracic wall.

Now find with tracer and forceps the great blood-vessels leaving the
cranial end of the heart (see Fig. 118). Take the greatest pains not to
injure them. Find the aorta and aortic arch (p. 281); the left
subclavian artery (p. 283) (continuous with the axillary); the
innominate artery (p. 282), and the beginnings of its three branches
(see Fig. 115). Find also the superior vena cava, the innominate veins,
and the subclavian vein, continuous with the axillary vein.

I. Study the smaller branches of the thoracic aorta (p. 283, and Fig.
118)--the intercostals, the bronchial and œsophageal arteries, and the
first pair of lumbar arteries. (The coronary arteries will be examined
later.)

II. Dissect the subclavian and its branches (p. 290) as follows:

 1. The internal mammary (p. 292). Follow it onto the ventral wall of
the abdomen. Follow the vein at the same time (p. 318).

 2. The vertebral artery (p. 291). Find its beginning, but do not trace
it at present.

 3. The costocervical axis (p. 292). Find its beginning, and trace the
superior intercostal branch some distance The other branches are not to
be followed at present.

 4. The thyrocervical axis (p. 293). Find its beginning, but do not
trace it at present.

 5. The axillary artery (continuation of the subclavian) (p. 294).
Follow its branches, tracing at the same time the axillary vein (p.
318). (Consult Fig. 122.) In tracing the blood-vessels, separate the
muscles, but do not cut them except where absolutely necessary. (The
muscles should be reviewed as the vessels are traced.)

The following notes may be of assistance in following the different
branches:

(_a_) The anterior thoracic was probably cut in dissecting the pectoral
muscles; it may be found, but its distal end is probably cut off.

(_b_) The long thoracic is easily followed.

(_c_) The subscapular. Follow the main artery before dissecting its
branches. Where the subscapular disappears between the long head of the
triceps, the latissimus dorsi, and the scapula, it may be traced and
found again as follows: Remove the skin from the outer side of the
shoulder,--taking great pains to remove _only_ the skin and not to
injure the vena cephalica (p. 319), a large vein that lies just beneath
the skin on the lateral surface of the shoulder, coming from the elbow.
The branches of the subscapular will be found appearing on the lateral
surface of the arm in the angle between the spinotrapezius, the long
head of the triceps, and the infraspinatus. The distal branches may then
be followed.

(_d_) The posterior circumflex (p. 296) may be traced distad in a
similar manner, by seeking it beneath the caudal border of the
spinotrapezius. (Do not injure the vena cephalica.)

(_e_) The other branches of the brachial artery and vein present no
difficulty till we come to the collateralis radialis superior (Fig. 122,
_x_). This must be traced with great care, along with the vena mediana
cubiti (p. 319, and Fig. 122, _y_). Remove the skin from the extensor
side of the forearm, taking great pains not to remove anything more than
the skin. The artery and vein lie beneath the skin and should be traced
to the hand (see Fig. 130).

Along with the collateral radial artery trace the vena cephalica (p.
319, and Fig. 130, _a_ and _c_). Follow it across the shoulder, noting
the branch to the posterior circumflex vein.

The remainder of the blood-vessels of the arm present no special
difficulty (see Figs. 123 and 124).

Make a diagram of the subclavian artery, as far as dissected.

III. Remove the skin from the sides of the neck, exposing the
sternomastoid muscles and the external jugular veins crossing them (see
Fig. 131). Clean the surface of the sternomastoid muscles, without
injuring the vein; separate the two muscles caudad, and cut each close
to the attachment to the sternum. Find the sternohyoid and sternothyroid
muscles, and cut them close to their attachment to the first rib.
Uncover the right side of the thorax in the same way as the left, cut
the ribs without injury to the nerves and vessels of the right axilla,
cut the internal mammary artery and vein (after tying the latter), and
thus remove the sternum with nearly the entire thoracic wall.

The blood-vessels of the thorax may now be more completely exposed. (If
the nerves are to be dissected on the same specimen, find the phrenic,
vagus, and sympathetic nerves (Fig. 157), and take the greatest pains
not to injure them.)

 1. The coronary arteries and the veins of the heart (pp. 281 and 316).

 2. The superior vena cava (p. 316). Find its branches. Trace the azygos
as far back as the diaphragm without dissecting it at all.

Find the division of the innominate (p. 318) into subclavian and
external jugular.

Trace next--

 3. The external jugular (p. 319). Remove the skin from the side of the
face and trace its branches (Fig. 131). The internal jugular, vena
facialis profunda, the submentalis, and the deep terminal branches of
the posterior facial cannot be followed at this time; veins shown on
Fig. 131 should all be found, however.

 4. Trace the thyrocervical axis and its branches (p. 293). Add them to
your diagram of the subclavian.

 5. Follow the common carotid artery (p. 283) and internal jugular vein
(p. 320). Find the division of the common carotid into its terminal
branches and then dissect its lateral branches and those of the internal
jugular (see Fig. 119).

 6. The external carotid (p. 285, and Fig. 119). Follow its branches
with the exception of the internal maxillary.

 7. The internal maxillary (p. 287). Find its inferior alveolar branch
first and follow it by cutting away with bone-forceps the ventral border
of the lower jaw. To follow its other branches and those of the carotid
plexus, remove the zygomatic arch, cut the temporal, masseter, and
pterygoid muscles, and cut the mandible behind the incisor teeth and
remove it. The branches which pass into the skull are not to be followed
at present. The posterior facial vein (p. 323), the vena facialis
profunda (p. 323), and the submental vein (p. 323) may be followed at
the same time.

 8. The internal carotid (p. 285). Follow it to the point where it
enters the cranium.

 9. Trace the other branches of the costocervical axis (p. 292). To do
this, cut the arteries and nerves of the axilla on the side on which
they have been dissected, allowing the arm to fall backward. Then trace
the branches of the costocervical axis with tracer, scalpel, and
bone-forceps, taking care not to injure the vertebral artery. Add these
branches to your diagram of the subclavian.

10. The vertebral artery (p. 291). Trace it to the foramen
transversarium of the sixth cervical vertebra. Then with bone-forceps
follow it to the atlas and into the atlantal foramen. Add this to your
diagram of the subclavian.

11. The basilar artery (p. 291) and the other arteries of the brain (p.
289) are best studied on a preparation, similar to that shown in Fig.
121. To obtain such a preparation it is only necessary to remove the
brain (for directions, see p. 462) of a specimen in which the arteries
have been injected.

(12. Veins of the brain and dura mater (p. 324). These can be worked out
only with much difficulty, except on specimens injected with gelatine.
The skull must be chipped away and the veins followed without destroying
them.)

13. Trace the pulmonary veins (p. 315) (filled with red injection) and
the pulmonary artery (p. 280).

IV. Vessels in the abdominal cavity.

 1. Open the abdominal cavity; find the superior mesenteric vein (p.
326, and Fig. 132) in the duodenal mesentery near the border of the
pancreas. Inject this in both directions with white starch and then
dissect the portal vein and its tributaries without injuring any of the
structures in the abdomen (p. 326, and Fig. 132).

 2. Follow the inferior vena cava (p. 325) from the heart to the
diaphragm and then follow it to its tributaries in the abdominal cavity.

 3. Dissect the branches of the abdominal aorta (p. 301) and of the
inferior vena cava (Fig. 126). Make diagrams of the vessels dissected
and review as far as necessary the viscera concerned.

V. The external iliac and its branches (vessels of the hind limbs) (pp.
309 and 329, and Figs. 127, 128, and 163).

Follow the branches of the external iliac arteries and the corresponding
veins in the same manner as the vessels of the arm were traced, cutting
the muscles only so far as absolutely necessary. Make diagrams of the
vessels dissected.

Make a diagram (_a_) of the arterial system as a whole; (_b_) of the
venous system as a whole.

THE LYMPHATIC SYSTEM (p. 330).

It will hardly be found practicable to have each student make a
dissection of the lymphatic system, and such parts of it as are to be
studied may best be shown on a specimen prepared for demonstration
purposes.

The thoracic duct and the receptaculum chyli may be demonstrated by the
following well-known method: A lean cat is fed with milk about two hours
before killing it. An egg may be beaten up with the milk to advantage.
Kill the cat with chloroform, and inject the arteries with colored
starch through the femoral, in the usual way. The thoracic duct, the
receptaculum chyli, and the lymphatics leading to the receptaculum chyli
will be colored white by the milk, and can therefore be easily followed.
For this purpose the abdomen should be opened, and the left side of the
thorax removed, as in the dissection of the blood-vessels. The thoracic
duct will be found at the left side of the aorta and may then be traced
in both directions.

For a more complete study of the lymphatics they should be injected.
This is done as follows: Make a glass canula with a small point, and
leave the point sharp. Connect this to the syringe by means of a rubber
tube. Use a saturated solution of soluble Prussian blue as injecting
fluid. Employ a freshly killed animal.

For injecting the lymphatics of the limbs, make with some pointed
instrument, as the tracer, a small hole in one of the pads on the sole
of the foot. Introduce the point of the canula into this opening and
inject the fluid. This will pass into the spaces in the connective
tissue of the pad, which will swell up, and the colored fluid will pass
from the connective-tissue spaces into the lymphatics. Pressure must be
maintained with the syringe for a considerable time,--fifteen minutes to
a half-hour for a good injection of the main trunks of the lymphatics of
the limbs. The movement of the fluid should be facilitated by pressing
and manipulating the limb at the same time with the hand,--in such a way
as will tend to drive the fluid proximad.

The lymphatics of the head may be injected in a similar manner, the
canula being introduced into the upper and lower lip, or into the bare
surface at the end of the nose.

The internal lymphatic vessels may be injected by injecting the
lymphatic glands with which they are connected. This may conveniently be
done as follows: Draw out to a fine point the tip of an ordinary pipette
or medicine-dropper. The point should be fine, but should taper rapidly
in a conical fashion, so that when the point is inserted the part of the
glass tube behind it will close up the opening.

Fill the pipette with soluble Prussian blue; insert the point into the
gland, and inject the fluid slowly. The lymphatic vessels passing from
the glands will be filled. By injecting thus the large lymphatic gland
(“pancreas Aselli”) in the mesentery, the abdominal lymphatics, the
receptaculum chyli, and the thoracic duct may be injected.

By using thin gelatine colored with Prussian blue as an injecting fluid
permanent preparations may be obtained; of course the process of
injection is then less simple, and should be looked up in some manual of
methods.

NERVOUS SYSTEM.

I. THE SPINAL CORD (p. 335).

Use the specimen on which the muscles were dissected. (Or if the
peripheral nerves are not to be dissected on the specimen used for the
blood-vessels, that may be employed.)

Make a longitudinal dorsal median incision of the skin, between the back
of the head and root of the tail. Reflect the skin for one or two inches
on each side of the incision and cut away the muscles covering the
neural arches of the vertebræ from the third cervical to the seventh or
eighth thoracic inclusive.

Remove with bone-forceps the neural arch of one of the last cervical
vertebræ and find the spinal nerve emerging from the intervertebral
foramen. Isolate the nerve for a short distance, then proceed craniad,
removing the neural arches on one side and isolating the nerves until
the third has been uncovered. The ganglion of the second nerve should be
sought among the muscles on the dorsal surface between the atlas and
axis, and after it has been isolated the arch of the axis may be
removed. (The nerve may be found beneath the clavotrapezius and traced
to the ganglion.)

The ganglion of the second nerve should be isolated in or near the
atlantal foramen, the muscles to which it passes turned aside, and the
arch of the atlas removed. Having thus uncovered the first two or more
spinal ganglia, proceed caudad, removing the vertebral arches, until the
whole cord and its nerves are exposed. Then--

 1. Study the cord, enlargements, filum terminale, etc. (p. 334, and
Figs. 133 and 136).

 2. Slit open and reflect the dura mater (p. 337) for an inch or two.

 3. Demonstrate the arachnoid by pulling it off with forceps.

 4. Reflect the pia mater in the same way as the dura mater.

 5. Study the fissures and grooves of the cord.

 6. Cut across the cord with fine scissors at the point where it is
freed from its membranes and examine the section. Note the arrangement
of gray and white matter and the fissures and grooves, particularly the
anterior or ventral. Demonstrate the central canal with the blowpipe.

 7. Study the origin of the spinal nerves (p. 337). Count them.
Direction of exit? Carefully clean one in the thoracic region from dura
mater and connective tissue, with fine scissors, and study dorsal and
ventral roots and ganglion (see Fig. 135). Then follow it out and find
its dorsal ramus and ventral ramus and the communicating branch of the
latter with the sympathetic system. Do not trace the peripheral branches
of the nerve at present.

II. THE BRAIN (p. 339).

The brain will usually be found to be in an entirely satisfactory
condition for study in any specimen injected with five per cent.
formalin or the glycerine and formalin mixture. The brain is a little
swollen, but all parts are well preserved, and the white and gray matter
are clearly marked off from each other. Either the specimen used for the
muscles or that employed for the blood-vessels may therefore be
used,--or if the brain was removed from the specimen employed for the
viscera, that will be satisfactory.

The following directions for removing the brain are designed for
specimens preserved as above. For removing the _fresh_ brain the process
is essentially similar, but as the brain is then very soft, care should
be taken not to tear it. The fresh brain should be preserved in the
alcohol-formalin mixture given below, and should be allowed to rest only
on some soft substance, as absorbent cotton.

Remove the head from the body by cutting through the neck a little
craniad of the first rib if this has not already been done. Remove all
skin, muscles, and other soft parts from the head and cervical vertebræ,
as far as possible. Remove the structures in the orbit by cutting
through the zygomatic arch at each end, and removing it. The lower jaw
should also be removed, if this has not already been done. (If a fresh
specimen is used, and the head is to be employed for other purposes, the
brain can be removed without separating the head from the body, and
without taking away the lower jaw and other structures on the ventral
surface of the skull.)

Have at hand dissecting-instruments and a dish containing alcohol and
formalin in the following proportions (Parker and Floyd’s mixture):

  95 per cent. alcohol     6 parts
   2 per cent. formalin    2 parts

In the bottom of the dish should be placed a little absorbent cotton, to
support the brain.

In removing the brain have at hand entire and dissected skulls and note
the relations of parts on these as far as necessary before cutting the
specimen.

With bone-forceps make a small opening in the parietal bone so as to
expose the dura mater, but do not cut through the dura mater. With some
blunt instrument free the dura mater from the bone about the opening,
and continue to cut away the bone until the dorsal and lateral faces of
the cerebrum are fully exposed craniad of the tentorium. The olfactory
bulbs (Fig. 137, _I_) should be exposed carefully and as fully as
possible. Cut away the dorsal arch of the atlas and carefully insert the
forceps in the foramen magnum and, working as before, remove the
squamous portion of the occipital and the parietal bones as far as the
tentorium and as far ventrad as possible. Leave the dura mater intact if
possible. Free the surface of the tentorium from the dura mater,
carefully separate slightly the cerebellum and cerebrum; insert the
bone-forceps (not too far) with the blades inclined from without
ventromediad, and cut the tentorium on each side. Remove it slowly,
cutting adhesions to the dura mater. That part of the dura mater which
dips between the cerebral hemispheres is the falx cerebri. Cut the dura
mater along both sides of the falx cerebri and remove it by turning it
down at the sides and cutting it at the level of the cut edge of the
bone. Remove it also from the cerebellum and notice how it dips down on
both sides of the tentorium and in close contact with it. Cut the falx
at the cranial end between the olfactory bulbs and cut the tentorial
dura (cut its adhesions, but do not remove with it the pineal body). The
falx and tentorial dura may then be removed.

Allow the head to hang sideways over the dish of alcohol-formalin in
such a way that the brain will tend to fall out of the cranium. Free the
olfactory bulbs from the bone. Then begin at the caudal end and tilt the
brain out with the handle of a scalpel. In doing this note carefully and
cut the cranial nerves. They should be left with central ends as long as
possible, and those on the side which is uppermost should be cut first.
In doing this refer to the foramina in the base of the skull and to Fig.
138. Take especial pains also not to break off the hypophysis, which is
lodged in the sella turcica.

The brain falls out and rests with its dorsal surface on the cotton. Now
remove the remainder of the dura mater, carefully cutting all adhesions
to nerves. Remove also the pia mater, as far as that can be done without
pulling off at the same time parts of the brain-substance. Preserve the
brain in the alcohol-formalin mixture.

_Study of the Brain._--In the study of the brain demonstration specimens
are to be used as much as or more than your own specimen. See everything
on a demonstration preparation before attempting to expose it in your
own specimen.

I. Examine the brain of a shark or of a frog. Cranial nerves may be
neglected, but the divisions of the brain should be recognized in dorsal
and ventral views and in longitudinal sections, and sketched.

II. Read the general description of the cat’s brain (pp. 339-343), using
your own specimen and a longitudinal section. Cut nothing on your own
specimen except when especially directed to do so. Study the cavities on
a preparation. Compare the diagrams (Figs. 139 and 140) and the figures
of the brain.

III. Study the individual parts as follows. To avoid errors make
constant reference to preparations and figures.

 1. The medulla (p. 344 and Figs. 138 and 141). Use your own specimen
and a preparation and dissect out carefully the cranial nerves on your
own specimen.

 2. The cerebellum (p. 347). Study it entire, then to expose the fourth
ventricle (p. 349) slice away with a very sharp scalpel one-half of the
cerebellum by making a median longitudinal incision and then horizontal
incisions.

 3. The pons (p. 347).

 4. The mesencephalon (p. 351, and Figs. 141 and 142). Study it first in
a preparation. Then study the floor on your own specimen; origin of
third nerves.

 5. The diencephalon (Figs. 141 and 142). Study the roof and thalami and
the pineal body on a preparation and on a longitudinal section; the
floor on your specimen.

 6. The telencephalon (p. 357). (Note that only _one_ side of this is to
be dissected.)

_a._ Study it externally; sulci and gyri (Figs. 145 and 146).

_b._ Examine a preparation showing the corpus callosum (Fig. 147). Then
slice away with a very sharp scalpel the top of _one_ hemisphere nearly
to the corpus callosum (see the preparation). Expose the corpus callosum
on this side to its cranial and caudal borders, by _tearing_ away the
brain-substance at its side and above it.

_c._ Raise the corpus callosum at the side and remove it, thus exposing
the lateral ventricle in which note the septum pellucidum and fornix,
the corpus striatum, and choroid plexus of the lateral ventricle (Fig.
148). (These are to be exposed on _one_ side only, the other being left
intact.)

_d._ Expose the anterior and inferior horns of the ventricle and find
the hippocampus, the fimbria, caudal part of the fornix, the foramen of
Monroe, the anterior commissure. See all these also on a preparation
(Fig. 148).

_e._ Remove the occipital and parietal portions of the cerebrum, on the
side already dissected, so as to expose the roof of the third ventricle
and the midbrain in your specimen, and note the pineal body, choroid
plexus of third ventricle, and structures on the roof of the midbrain
(Fig. 141).

_f._ Remove the choroid plexus or roof of the third ventricle and study
again the thalami (Fig. 141).

_g._ Make a longitudinal section of the brain, in the following manner:
Use a very sharp large scalpel, or a razor. Have this wet with the
alcohol mixture at the time of using. Place the brain ventral surface
down on a sheet of cork or a block of soft wood, the long axis of the
brain coinciding with the direction of grain of the wood. Holding the
brain firmly with one hand, place the wet knife between the hemispheres
with its edge resting on the corpus callosum. See that it is in the
median plane and parallel with the long axis of the brain. See also that
it is not inclined to one side or the other, so that it will make on
cutting a median section throughout. The point of the knife should just
reach the cork or wood between the olfactory bulbs. Now draw the knife
caudad, keeping its point against the cork: the brain will thus be
divided.

If the section is not exactly median, observe the amount of divergence
by placing the two halves together and finding the median ventral line.
Then on the half that has _too much_ slice away thin shavings until the
cavities are exposed, showing the section to be median. Compare with a
demonstration section or Fig. 143. Draw the section and compare with a
section of shark’s brain (see Fig. 143).

_h._ Study a series of transverse sections, identifying parts. Observe
especially in these sections the fornix, corpus callosum, and
ventricles, and the distribution of white and gray matter (see Figs.
149-153).

III. PERIPHERAL NERVOUS SYSTEM.

(There are some advantages in dissecting the eye with its muscles before
dissecting the nerves, as a knowledge of the eye-muscles is presupposed
for dissecting some of the cranial nerves. For directions on the eye,
see p. 469.)

A new specimen should be used, if possible, for the peripheral nervous
system, though that used for the blood-vessels can be employed, at
considerable disadvantage.

Prepare as for the blood-vessels. The arteries should be injected with
red starch, to aid in tracing the nerves.

 1. THE CRANIAL NERVES (p. 369) AND SYMPATHETIC SYSTEM (p. 404).

 1. Reflect the skin covering the sternomastoid muscle, and make a
longitudinal incision of the muscle so as to expose the carotid artery.
Lying along the artery find the combined trunk of the sympathetic and
vagus nerves. Follow the vagus (p. 378) first craniad; transect the
muscles as necessity arises, and find its ganglion nodosum and at the
same time locate the superior cervical ganglion of the sympathetic nerve
(p. 404, and Fig. 156). Then find the hypoglossal nerve (Fig. 156, _b_),
passing outside of the carotid artery to the tongue, and the accessory
(Fig. 156, _c_), passing to the trapezius. Cut and reflect the digastric
muscle and find the small glossopharyngeal nerve (Fig. 156, _a_),
passing to the surface of the bulla and then beneath the carotid artery.

 2. Follow the vagus (p. 378) caudad to its termination. To do this it
is necessary to remove one side of the thorax, as in dissecting the
blood-vessels. Do not injure the nerves of the axilla, nor the phrenic
or sympathetic nerves. For the vagus in the thorax, compare Fig. 157.
Find the branches of the nerve; in dissecting them, pull on them to make
them tense. They are then more easily visible. To dissect the abdominal
portion of the vagus, open the abdominal cavity, and compare Fig. 164
(p. 407).

 3. Dissect the sympathetic (p. 404), following it and its branches to
the pelvic region (Figs. 156, 157, and 164).

 4. The hypoglossal (p. 383, and Fig. 156, _b_).

 5. The glossopharyngeal (p. 378, and Fig. 156, _a_).

 6. The accessory nerve (p. 382, and Fig. 156, _c_; Fig. 158, 1).

Cut away a portion of the tympanic bulla and the base of the skull,
sufficient to follow these nerves in the jugular foramen, to the brain.

 7. Locate the stylomastoid foramen and pick away overlying tissue until
the facial nerve is found emerging and then follow its branches to their
distribution (p. 375, and Fig. 155).

 8. Expose the ventral surface of the pterygoid muscles just mediad of
the angle of the jaw. Divide and reflect them, and the mandibular
division of the fifth nerve (p. 373, and Fig. 154) will be found dorsad
of them and of the internal maxillary artery. The chorda tympani (p.
375) passes ventrad of the artery to join the lingual. Follow out (1)
the lingual branch (p. 375) (with the chorda tympani), and (2) the
inferior alveolar (p. 375) by cutting away the ventral border of the
mandible. Then cut the mandible near the canine tooth, and pull it to
one side, and follow out the muscular branches of the mandibular nerve.

 9. Remove the mandible and find the maxillary nerve (p. 371) emerging
from the foramen rotundum. Follow its branches and find the
sphenopalatine ganglion (p. 372).

10. Remove the zygoma so as to expose the whole ventral aspect of the
orbit. Carefully pick away the fat in the orbit without injuring any
nerves, so as to expose the four recti muscles and the inferior oblique
(see p. 411, and Fig. 166). Find the abducens nerve (p. 375, and Fig.
154), entering the dorsal edge of the lateral rectus, and follow it
back. Look on the inner surface of the inferior rectus for the branch of
the third nerve (p. 369) which supplies it. Find the branch of this
nerve which runs to the inferior oblique muscle, and on it the ciliary
ganglion; find the branches to the ciliary ganglion from the ophthalmic
nerve and follow them (p. 371). Follow also the short ciliary nerves (p.
370) to the eyeball.

11. Trace the third nerve (p. 369) to its foramen of exit and find its
branches. Where it passes between the superior and lateral recti, find
the ophthalmic nerve (p. 370) by its side and trace its branches.

12. Find the fourth nerve (p. 370), passing outside of the lateral
rectus at its origin and entering the superior oblique.

13. Follow the third, fourth, fifth, and sixth nerves into the skull by
chipping away the bone and removing the dura. Note the semilunar or
Gasserian ganglion (p. 370, and Fig. 138, _k_) and the origin of the
fifth nerves from it, and the relation of the ventral root of the fifth
nerve to the mandibular nerve.

 2. SPINAL NERVES.

The spinal nerves may be dissected on the same side used for dissecting
the cranial nerves. (If an undissected specimen is used, remove the skin
from the side of the neck, and cut the sternomastoid, sternohyoid, and
sternothyroid muscles, as directed for the vagus and sympathetic.)

_Cervical Nerves_ (p. 383).--The ventral rami of the cervical nerves are
to be sought as they pass out between the bundles of the scalenus, or
between the scalenus and longus capitis, in the neck. This region has
already been uncovered in dissecting the vagus and sympathetic (Fig.
156). Dissect first the _second_ cervical (p. 385). Find its ventral
ramus as it emerges between the levator scapulæ ventralis and
cleidomastoid (Fig. 158, 2), and follow its branches,--the auricularis
magnus (5) and cutaneus colli (6). Find its _dorsal_ ramus, the great
occipital nerve (p. 384), by reflecting the clavotrapezius muscle; the
nerve will be found emerging from the underlying muscles close to the
craniomedial angle of the clavotrapezius, near its origin. Trace the
nerve in both directions.

The ventral ramus of the first cervical (p. 385) will be found emerging
from beneath the wing of the atlas, a little distance craniad of the
second (Fig. 156, _j_). Trace it. To find its short dorsal ramus, the
suboccipital nerve (p. 384), it is necessary to dissect apart the
muscles on the dorsal side of the atlas till the nerve is found passing
from the atlantal foramen.

Dissect the third, fourth, and fifth nerves (p. 385, and Fig. 158).

_Brachial Plexus_ (p. 386, and Figs. 159 and 160).--The brachial plexus
has been partly uncovered in dissecting the vagus and sympathetic. (If a
new specimen or the opposite side is used, reflect the skin from the
ventral surface of the thorax and arm, and cut the pectoral muscles,
thus uncovering the vessels and nerves of the axilla.) Reflect the skin
from the ventral surface of the upper arm. (Do not use scalpel, but tear
the skin from the muscles. In this way the nerves will be seen passing
to the skin, while if the scalpel were used the nerves might be cut.)

Tie the axillary vein or its two branches in two places, and cut the
vein between the tied regions. Leave the arteries as guides for
dissection, but remove the veins. Now clean thoroughly the nerves
forming the brachial plexus as they pass from the thorax or neck. Be
careful not to injure any of the fine nerves or the interconnections of
the nerves in doing this. Find and distinguish clearly the fifth, sixth,
seventh, and eighth cervical nerves and the first thoracic, as they
emerge from the neck or thorax. (Compare Fig. 159 and Fig. 157,
_V_-_VIII_ and _I′_.)

Follow out the branches of the plexus, noting the origin and
distribution of each branch, in order to determine its name. To follow
the phrenic (p. 388, and Fig. 157, _f_), remove a portion of the
thoracic wall. In following the other branches of the plexus, pull back
the skin wherever an exposure is to be made, and separate the muscles.
The epitrochlearis may be cut near the elbow, and the clavobrachial near
the shoulder. In following the interosseous branches of the median nerve
the fifth head of the flexor profundus, and the extensor brevis
pollicis, may be cut. As a rule it will not be necessary to cut other
muscles.

_Thoracic and Lumbar Nerves._--One or two of the thoracic nerves (p.
393) should be dissected from the outside by finding the intercostal
nerve along the caudal border of one of the ribs and tracing it in both
directions. The nerve may be exposed by removing the external muscles
covering the rib, and cutting the external intercostal muscles. The
dorsal ramus should be traced after the ventral ramus has been studied.

The first lumbar nerve (p. 395) should be dissected in the same way.

The other lumbar and sacral nerves (pp. 395-400) are best dissected from
within.

The alimentary canal and its appendages should be removed from the
abdomen, leaving only five or six centimeters of the caudal end of the
rectum. The kidneys and urogenital organs may be left, to be removed
during dissection. (Compare Fig. 162.)

Turn one of the kidneys to the other side, and find the second lumbar
nerve (Fig. 162, _a_) appearing at the lateral border of the iliopsoas
muscle. Trace it to its origin; trace it also distad, following both
branches. It will be necessary to trace the nerves through the abdominal
wall, then find them from the outside, and follow them to their
distribution.

The third nerve (Fig. 163, _b_) may be found by dissecting apart the
fibre-bundles of the iliopsoas and psoas minor, and following in the
same way. The kidneys, ureters, vena cava, and aorta may be removed as
occasion arises.

The remainder of the lumbar nerves may be found in order, in a similar
manner. Follow the saphenous nerve and its branches (p. 397) by removing
the integument from the medial side of the leg (see Fig. 127, p. 310).
To dissect the sacral nerves (p. 399) separate the innominate bones at
the pubic symphysis and divaricate them. Find the nerves arising from
the sacral plexus, by cutting the levator ani muscle. After N.
hemorrhoidalis inferior and N. pudendus have been traced, the rectum and
urogenital organs may be removed, taking great care not to remove more
than is necessary. To dissect the great sciatic nerve (p. 400, and Fig.
163), separate the biceps and caudofemoralis near their proximal ends
and find the large nerve-trunk (_a_). Then lift the biceps away from the
nerve, cut that muscle near its middle, and reflect it. The nerve may
now be followed to its terminal branches; during the process cut the
muscles only when absolutely necessary. The inferior gluteal nerve (_i_)
will be found on the dorsal surface of the great sciatic; by cutting the
caudofemoralis and gluteus maximus muscles near their insertions and
turning them back the distribution of the nerve may be followed. The
superior gluteal (_j_) will be found at the cranial margin of the
pyriformis by reflecting the gluteus medius in the same way; the tensor
fasciæ latæ may also be cut.

SENSE-ORGANS.

I. THE EYE (p. 410).

Use any specimen on which one side of the head has been left intact.
Remove the head from the body by cutting through the neck a little
craniad of the first rib.

Study the eye externally. Observe the eyelids, the conjunctiva,
nictitating membrane with its cartilage, and the Harderian gland (Fig.
165); the two openings of the lachrymal duct, the Meibomian glands if
possible.

Remove the zygomatic arch and expose the orbit and the structures which
it contains. Study the periorbita (p. 409), and find the lachrymal gland
(p. 410).

Study the muscles of the eyeball (p. 411, and Fig. 166). The lateral
rectus on the lateral surface will perhaps be first found, and its
tendon traced beneath the inferior oblique. Use great care not to injure
the levator palpebræ superioris.

After studying the muscles, find the optic nerve. Cut it and the
muscles, and remove the eyeball for farther study.

_The Eyeball_ (p. 412, and Fig. 167).--For an examination of the eye it
is well to have a fresh specimen and one hardened in formalin or
alcohol. The hardened specimen is more essential, however. An eye from
one of the specimens used in dissection is usually satisfactory. All
accessory portions should be trimmed from the eyeball, leaving only the
spherical ball with a short stalk formed by the optic nerve.

Observe such features of the eye as can be seen externally: the optic
nerves, sclerotic, cornea, iris, and pupil. This should be done on a
fresh specimen, if one is at hand. The changes in size and form of the
pupil can be observed in the living cat by changing it from a light to a
dark place and _vice versa_.

_Dissection._--Examine the internal structures on a preparation. Then
with fine scissors and forceps remove from the eye about one-fourth of
the wall, in the form of a quadrant having one point at the optic nerve,
the other at the centre of the cornea. The coats of the eye can then be
studied on the piece removed, while the other structures will be visible
within the eyeball. No special directions are necessary for observation
of the structures described, unless it be the capsule of the lens and
the zonula ciliaris. The capsule of the lens may be demonstrated by
tearing a bit of it off with fine forceps. The zonula ciliaris is easily
seen by divaricating the edges of the cut made in removing the quadrant,
so as to stretch the fine fibres of which the zonula is formed.

II. THE EAR (p. 415).

(The muscles of the external ear are of little practical importance, and
will doubtless usually be omitted.)

(1) The External Ear. Read the description of the external ear (p. 415),
verifying it by examination and comparison of an ear still covered with
integument, in the natural condition, and of a preparation of the
isolated cartilages of the ear (Fig. 168). The latter may be obtained by
dissecting the skin and muscles from a fresh ear.

(2) The scutiform cartilage (p. 418) should be observed in the natural
position, and as isolated.

(3) The muscles of the external ear (p. 418, and Fig. 169). Those
connecting the external ear with other parts of the head have been
studied in connection with the facial muscles. The remainder will be
studied on an external ear removed according to the directions given on
page 435.

Remove the integument from the convex surface of the auricle,
sufficiently to expose the entire extent of the muscles.

 1. The rotator auris. Transect.

 2. The adductor auris superior (Fig. 169, 1).

 3. The adductor auris medius (2).

 4. The transversus auriculæ (Fig. 63, _i_, p. 97).

 5. The auricularis externus (Fig. 169, 10).

 6. The helicis (Fig. 169, 3). To expose this it will be necessary to
remove the integument from along the cranial border of the inner surface
of the auricle.

 7. The antitragicus (Fig. 169, 6). Remove the integument farther if
necessary.

 8. The tragicus medialis (Fig. 169, 5, 5′).

 9. The conchæus externus (Fig. 169, 9).

(4) Remove the tympanic bulla and petrous bone from the rest of the
skull, by the use of bone-forceps and scalpel. Trim away all soft tissue
(including the cartilaginous auditory meatus), and all other bony parts
from these, but leave them uninjured.

(5) Find the Eustachian tube and study it (p. 423).

(6) Study specimens of the bones of the middle ear (p. 423, and Figs.
171 and 172).

(7) The middle ear should be studied on a demonstration preparation,
then dissected as follows:

Remove with bone-forceps the medial side of the tympanic bulla (the
entotympanic). Note the two cavities within the bulla, with the shelf
separating them. Observe the fenestra cochleæ. Now remove with the
forceps the shelf, first breaking through the middle part, then removing
the rest with care. Remove part also of the membranous lining of the
cavity, till the inner surface of the tympanic membrane, with the
malleus crossing it, is visible. Observe the tensor tympani muscle (p.
424) attached to the malleus by its small tendon. Next, with
bone-forceps, fracture the thick, bony portion uniting the caudal end of
the petrous with the caudal part of the ring of bone surrounding the
external auditory meatus. These two parts may then be separated with the
fingers, leaving the petrous bone on one side, the meatus, tympanum, and
malleus on the other (Fig. 170). The head of the malleus may then be
observed, with the incus attached to it. Note also the stapes, in the
fenestra vestibuli, with the stapedius muscle (p. 424) attached to it.

(8) The internal ear (p. 424). Note the fenestra vestibuli and fenestra
cochleæ and the promontory (p. 34). Study the cochlea and vestibule on a
demonstration preparation and compare with Fig. 173. Then remove the
wall of the promontory and find the cochlea. Open the vestibule and find
as many of the openings of the semicircular canals as possible. Study
the semicircular canals on demonstration preparations, consulting Fig.
173. The semicircular canals may, if desired, be exposed on your own
specimen, by cutting away the surface of the bone in places indicated in
the description (p. 426), and inserting fine bristles (those from the
sensory hairs on the face of the cat are excellent for this purpose).

The membranous labyrinth (Fig. 173) may be isolated by decalcifying the
petrous bone with ten per cent. nitric acid, then dissecting out the
labyrinth. This is an operation of considerable delicacy, but at least
one or two specimens for demonstration should, if possible, be prepared
thus and kept in the laboratory.

INDEX.

  Abdominal aorta, 301
    arteries, 301
    cavity, 217, 218
    muscles, 153
      dissection, 441
    veins, 326
  Abducens nerve, 347, 375
  Abductor auris brevis, M., 100, 435; longus, M., 100, 435
    brevis pollicis, M., 184, 439
    caudæ (coccygis) externus, M., 137, 447; internus, M., 137, 446
    cruris, M., 195
    digiti quinti, M., 185, 439; secundi, M., 185
    medius digiti quinti, M., 215
  Accelerator urinæ, M., 271
  Accessory nerve, 346, 382
    process, 6, 8
  Acetabular bone, 76, 78
    notch, 79
  Acetabulum, 76, 78, 87
  Achilles, tendon of, 204, 206
  Acromiodeltoid muscle, 157, 438
  Acromion process, 62, 64
  Acromiotrapezius, M., 116, 436
  Adductor auris inferior, M., 104, 435; medius, M., 419, 470; superior,
    M., 419, 470
    digiti secundi, M., 185
    femoris, M., 198, 444
    longus, M., 199, 444
    medius digiti quinti, M., 215
    pollicis, M., 185, 439
  Aditus laryngis, 246
  Adrenolumbar arteries, 304
    veins, 326
  Alæ magnæ, 26, 27
    parvæ, 29
  Albuginea, 260
  Alcohol as preservative, 431
  Alcohol-formalin for brains, 463
  Alimentary canal, 221; dissection of, 449
  Alisphenoids, 25, 27
  Alveolar border, 39, 47
    nerve, inferior, 374, 375
    process, 39
  Alveoli, 48
  Ampulla (ear), 426
    of Vater, 236
  Anal glands or sacs, 239; constrictors of, 269
  Anapophysis, 6
  Anastomotica magna, A., 297
  Anconeus, M., 170, 438
  Anconeus internus, M., 170
    lateralis, M., 167
    longus, M., 168
    posterior, M., 168
  Angle of rib, 18
  Angular process, 19, 48
    vein, 321
  Ankle, bones of, 82
    ligaments of, 91
  Annularis, 72
  Annular ligaments, 75, 173, 213
  Ansæ, 386
  Anterior cerebral artery, 289
    circumflex artery, 296
    commissure, 357, 365
    facial vein, 321
    fossa, 59
    perforated substance, 362
    spinal artery, 291
    superior process, 78
    Sylvian gyrus, 359
    sulcus, 359
    thoracic artery, 294; nerves, 387
    tibial artery, 313
    transverse processes, 11
  Antibrachial fascia, 172
  Antibrachium, muscles of, 172
  Anticlinal vertebra, 6
  Antihelix, 416
  Antitragicus, M., 421, 470
  Antitragus, 417
  Anus, 239
    muscles of, 268
  Aorta, 275, 279, 281, 301
    abdominalis, 301
  Aortic plexus, 408
    semilunar valves, 279
    sinus, 279
  Apparatus digestorius, 221
    respiratorius, 243
    urogenitalis, 255
  Appendicular fossa, 35, 58
    lobe, 348
  Appendix, 429
  Aqueduct of Sylvius, 342, 343, 350, 351, 352
  Aqueductus cerebri, 342, 343, 350, 351, 352; Fallopii, 35
  Aqueous humor, 414
  Arachnoid, 337, 369
  Arbor vitæ, 349
  Arch, bicipital, 166
    supraorbital, 37, 51
    zygomatic, 47, 49, 52
  Area elliptica, 345
    ovalis, 345
    perforata posterior, 352
  Arm, arteries of, 294
    articulations of, 73
    bones of, 64
    muscles of, 156
      dissection of, 436
    nerves of, 388
    veins of, 318
  Arteria adrenolumbalis, 304
    alveolaris inferior, 288
    anastomotica magna, 297
    anonyma, 282
    articularis genu suprema, 311
    auricularis anterior, 287; posterior, 287
    axillaris, 294
    basilaris, 291, 292
    brachialis, 296
    bronchiales, 283
    carotis communis, 282, 283; externa, 285; interna, 285
    cerebelli anterior, 292; inferior posterior, 292
    cerebri anterior, 289; media, 289;
    posterior, 292
    cervicalis ascendens, 293; profunda, 293
    circumflexa femoris lateralis, 311; humeri anterior, 296; humeri
      posterior, 296; scapulæ, 294
    cœliaca, 301
    colica dextra, 304; media, 303; sinistra, 306
    collateralis radialis superior, 297; ulnaris, 297
    coronariæ, 275, 279, 281
    digitales dorsales, 297; plantares, 314
    dorsalis penis, 308
    epigastrica inferior, 309
    femoralis, 307, 310
    gastrica sinistra, 303
    gastroduodenalis, 302
    gastroepiploica dextra, 303
    genu posteriores, 313
    glutea inferior, 308; superior, 308
    hemorrhoidalis media, 308; superior, 306
    hepatica, 302
    hypogastrica, 307
    ileocolica, 304
    iliaca externa, 307, 309; interna, 307
    iliolumbalis, 306
    infraorbitalis, 290
    intercostales, 283
    intercostalis suprema, 293
    interosseæ, 298, 300
    lienalis, 303
    lingualis, 285, 286
    lumbales, 283, 306
    lumboabdominalis, 304
    mammaria interna, 292
    maxillaris externa, 285, 286; interna, 287
    mesenterica inferior, 306; superior, 303
    meningea media, 289
    metatarsea, 315
    occipitalis, 285
    œsophageæ, 283
    ophthalmica, 289
    palatina descendens, 290; minor, 290
    pancreaticoduodenalis inferior, 303; superior, 303
    phrenica, 304
    poplitea, 311, 312
    princeps pollicis et indicis, 300
    profunda brachii, 296; femoris, 309
    pulmonalis, 275, 278, 280
    pylorica, 302
    radialis, 297; recurrens, 298
    renalis, 304
    sacralis lateralis, 309; media, 301, 309
    saphena, 311
    spermatica externa, 309; interna, 304
    sphenopalatina, 290
    spinalis anterior, 291
    subclavia, 282, 283, 290
    subscapularis, 294
    superior profunda, 296
    suprascapularis, 293
    suralis, 313
    tarsea medialis, 315
    temporalis superficialis, 287
    thoracica anterior, 294; longa, 294
    thoracicodorsalis, 296
    thyreoidea ima, 283, 284; superior, 284
    tibialis anterior, 313; posterior, 313; recurrens, 314
    transversa colli, 293; scapulæ, 293
    ulnaris, 300; recurrens, 298
    umbilicalis, 307
    uterina, 308
    ventriculi dorsalis, 303
    vertebralis, 291
  Arteries (see Arteria), 280
    abdomen, 301
    arm, 294
    bladder, 307
    brain, 289, 291
    foot, 312, 314
    hand, 300
    kidneys, 304
    intestine, 304
    limbs, 294, 309
    liver, 302
    stomach, 303
  Artery (see Arteria)
    cystic, 302
    labial, 286
    mediastinal, 282
    ovarian, 306
    submental, 286
    superior laryngeal, 285
  Articular artery, superior, 311
    circumference, 67
    facet, 4
    processes, 6, 8
  Articulation, atlanto-occipital, 17
    intervertebral, 16
  Articulations of arm, 73
    hind limb, 86
    mandible, 61
  Arytenoid cartilages, 248
  Arytenoideus transversus, M., 250
  Astragalus, 82
  Atlantal foramen, 14
  Atlanto-occipital articulation, 17
  Atlas, 14
  Atrium dextrum, 275
    sinistrum, 279
  Attollens auris. M., 100
  Auditory bulla, 32
    meatus, external, 32, 33, 52, 55, 415, 416; internal, 35, 58
    nerve, 347, 377
    organ, 415
  Auricle (ear), 415
  Auricles of heart, 274, 275, 279
  Auricula, 415
  Auricular appendage, 275, 279
    arteries, 287
    cartilage, 415, 416
    facet, 10
    impression, 77
  Auricularis anterior, M., 104, 419
    externus, M., 420, 470
    posterior, M., 99
    superior, M., 100, 435
  Auricular nerve, 379; great, 385; posterior, 377
    vein, anterior, 324; posterior, 324
  Auriculotemporal nerve, 373
  Auriculoventricular septum, 274
  Axillary artery, 294
    border, 63
    nerve, 388
    vein, 318
  Axis, 15
  Azygos vein, 316

  Backbone, 1
  Back, fascia of, 126
    muscles of, 115, 123; dissection of, 442
  Basilar artery, 291, 292
  Basioccipital bone, 22
  Basisphenoid bone, 25
  Biceps brachii, M., 165, 438, 439
    femoris, M., 194, 444
  Bicipital arch, 166
    groove, 66
    tubercle, 64
    tuberosity, 67
  Bicuspid valve, 279
  Bile duct, 241
  Biventer cervicis, M., 132, 443
  Bladder, 256
    arteries of, 307
    ligaments of, 219, 257
  Blind spot, 414
  Blood vessels, 280
    dissection of, 456
    injection of, 456
  Body cavity, 217
  Body muscles, 115
  Bones, 1
    ear, 423
    head, 21
    pelvic extremities, 76
    preparation of, 430
    sesamoid, 73, 80, 86
    study of, 431
    thoracic extremities, 62
  Bony labyrinth, 425
  Brachial artery, 296
  Brachialis, M., 166, 438, 439
  Brachial plexus, 386; dissection of, 467; vein, 318
  Brachioradialis, M., 173, 438
  Brachium conjunctivum, 348, 349
  Brachium, muscles of, 164
    pontis, 347, 348, 349
    quadrigeminum inferius, 351, 354; superius, 351, 354
  Brain, 339
    arteries of, 289, 291
    diagrams of, 343
    dissection of, 464
    preparation of, 462
    preservation of, 462
    removal of, 462
    study of, 464
    veins of, 324
  Breast, muscles of, 144; dissection of, 437; nerves of, 387
  Broad ligament, 264, 266
  Bronchi, 252
  Bronchial arteries, 283
    veins, 318
  Buccæ, 222
  Buccal cavity, 221
    nerves, 377
  Buccinator, M., 106, 435
    nerve, 374
  Bulbocavernosus, M., 271, 454
  Bulbourethral glands, 261
  Bulbus olfactorius, 362
    urethræ, 261
  Bulla, auditory, 32, 55
    tympanic, 32, 55
  Burdach, column of, 337, 345

  Cæcum, 238
  Calf of leg, muscles of, 203
  Calcaneometatarsalis, M., 215, 445
  Calcaneus, 82, 83
  Callosal sulcus, 362
  Canal, alimentary, 221
    anterior palatine, 41
    condyloid, 24, 58
    facial, 35, 58
    Hunter’s, 311
    hypoglossal, 24, 58
  Canalis adductorius, 311
    facialis, 35, 58
  Canal, lachrymal, 40, 54, 410
    nasolachrymal, 40, 47, 54, 410
    of Huguier, 376
    posterior palatine, 45, 46, 54, 56
    pterygoid, 27, 56, 59
    sacral, 8
  Canals, semicircular, 425, 426
  Canine teeth, 225
  Caninus, M., 100, 435
  Capitatum, os, 70
  Capitulum, 18, 66
  Capsula lentis, 414
  Capsularis, M., 190, 444
  Capsule of Glisson, 302
    of lens 414
  Caput epididymis, 260
  Cardiac nerves, 380, 405, 406
    plexus, 380, 382, 405
  Cardinal veins, 328
  Carotid artery, common, 283; external, 285; internal, 285
    groove, 26
    plexus, 287
  Carpus, 69
  Cartilage, costal, 18
  Cartilages of larynx, 247
  Cartilago auriculæ, 415, 416
  Cauda epididymis, 260
    equina, 339
  Caudal muscles, 136; dissection of, 447
    vertebræ, 1, 11
  Caudoanalis, M., 270
  Caudocavernosus, M., 271
  Caudofemoralis, M., 195, 444
  Caudorectalis, M., 270
  Caudovaginalis, M., 272
  Cavernous sinus, 325
  Cavities of the skull, 57
  Cavity, abdominal, 217
    body, 217
    buccal, 221
    mediastinal, 218
    nasal, 59, 243
    pelvic, 218
    thoracic, 217
  Cavum nasi, 243
    oris, 221
    tympani, 422
  Central nervous system, 335
  Centrale, 69
  Centrum, 3
  Cephalica, V., 319
  Cephalobrachial muscle, 118
  Cephalohumeral muscle, 118
  Ceratohyal, 49
  Ceratohyoid muscle, 115, 440
  Cerebellar arteries, 292
    fossa, 57, 58
    gyri, 348
    hemispheres, 348
  Cerebellum, 341, 347
    arteries of, 292
  Cerebral aqueduct, 342, 343, 350, 351, 352
    arteries, 289, 292
    fissures, 359
    fossa, 58
    gyri, 359
    hemispheres, 341, 357
    peduncles, 351
    sulci, 359
    vein, inferior, 325
  Cerebri magna, V., 324
  Cerebrum, 341, 357
    arteries of, 289, 292
  Ceruminous glands, 416
  Cervical ganglia of sympathetic, 404, 405
    lymphatic glands, 332
    nerves, 383
    plexus, 386
    vertebræ, 1, 11, 15
  Cervicalis ascendens, A., 293; V., 320; profunda, A., 293
  Cervicofacial muscle, 95
  Cervix uteri, 266
  Chambers of eye, 414
  Cheek, muscles of, 105
  Cheeks, 222
  Chevron bones, 11
  Chiasma, optic, 342, 354, 355, 369
  Chiasmatic groove, 29, 59
  Choanæ, 60, 232, 244
  Chordæ tendineæ, 278
  Chorda tympani nerve, 375, 376
  Choroid, 413
    plexus of fourth ventricle, 350; of lateral ventricles, 353, 363,
      367; of third ventricle, 354, 355
  Ciliary body, 413
    folds, 413
    ganglion, 369, 371
    nerve, long, 371; short, 370
  Circle of Willis, 289, 292
  Circulatory system, 274; dissection of, 455
  Circulus arteriosus, 289, 292
  Circumference, articular, 67
  Circumflexa femoris lateralis, A., 311
    humeri anterior, A., 296; posterior, A., 296
    scapulæ, A., 294
  Circumflex nerve, 388
  Circumvallate papillæ, 227
  Clava, 345, 349
  Clavicle, 64
  Clavicula, 64
  Clavobrachial muscle, 157, 437, 439
  Clavotrapezius muscle, 118, 436
  Cleidomastoid muscle, 120, 436, 440
  Clinoid processes, 26, 29
  Clitoris, 264, 267
  Coats of the eyeball, 413
    of the testis, 258
  Coccygeal nerves, 404
  Coccygeus, M., 137
  Cochlea, 425
  Cœliac artery, 301
    ganglion, 406
    plexus, 406
  Cœlom, 217
  Colica dextra, A., 304
    media, A., 303
    sinistra, A., 306
  Collateral ligaments, 74, 88
    radial artery, 297
    ulnar artery, 297
  Colliculi inferiores, 349, 351
    superiores, 351
  Collum of rib, 19
  Colon, 237
  Colon, ligaments of, 219
  Columnæ carneæ, 278
  Columns of spinal cord, 336
  Commissura anterior, 357, 365
    labiorum, 222
    posterior, 355
  Commissure, middle, 354
  Common bile-duct, 241
    carotid artery, 282, 283
    iliac veins, 328
  Communicating branches of sympathetic, 406
  Complexus, M., 133, 443
  Compound terms, viii
  Compressor urethræ membranaceæ, M., 271, 454
  Concha auris, 415, 416
    nasalis superior, 42
    ventral nasal, 40
  Conchæus externus, M., 422, 470
  Condyle, occipital, 23, 52, 55
  Condyles of femur, 80
    tibia, 80
  Condyloid canal, 24, 58
    process, 48
  Conjunctiva, 409, 410
  Constrictor cunni, M., 272
    pharyngis inferior, M., 232, 451; medius, M., 233, 451; superior,
      M., 233
    vestibuli, M., 272
  Constrictors of anal glands, 269
  Conus arteriosus, 277
  Cor, 274
  Coracobrachialis, M., 164
  Coracoid border, 63, 64
    process, 63, 64
  Coracovertebral angle, 63
  Cord, spinal, 335
  Corium, 427
  Cornea, 412, 413
  Cornetoconchæus, M., 422
  Cornua of hyoid, 49
    of uterus, 266
  Coronal sulcus, 360
  Coronaria ventriculi, V., 326
  Coronary artery, 275, 279, 281
    ligament of liver, 221
    sinus, 277, 316
    sulcus, 274
    veins, 277, 315
  Coronoid fossa, 48, 66
    process, 48, 69
  Corpora mammillaria, 356
    quadrigemina, 351
  Corpus callosum, 357, 363
    cavernosum clitoridis, 267; penis, 263; urethræ, 261, 263
    ciliare, 413
    geniculatum laterale, 354; mediale, 351, 354
    luteum, 264
    of sternum, 20
    of vertebræ, 3
    pineale, 351, 355
    restiforme, 346, 348, 349
    spongiosum, 261
    striatum, 363, 367
    vitreum, 415
  Corrugator supercilii lateralis, M., 98, 435; medialis, M., 97, 435
  Cortical portion of kidney, 256
  Costæ, 18
    spuriæ, 19
    veræ, 19
  Costal cartilage, 18
    facet, 3, 5
  Costocervical axis, 292
    vein, 318
  Cowper’s glands, 261
  Cranial cavity, 57
    nerves, 346, 369; dissection of, 465
    portion of skull, 21
  Cranium, 21
  Cremaster muscle, 258
  Cremasteric fascia, 258
  Crest, external occipital, 24, 52
    nasal, 40, 42
    of ilium, 78
    of tibia, 81
    sagittal, 25, 50
  Cribriform plate, 43
  Cricoarytenoideus lateralis, M., 251
    posterior, 249
  Cricoid cartilage, 248
  Cricothyroid muscle, 249
  Crista helicis, 417
  Crucial ligaments, 88, 89
  Cruciate sulcus, 360, 361
  Crura cerebelli, 341, 348
    of diaphragm, 152
    of penis, 263
  Crural arches, 154
    fascia, deep, 206
    muscle, 202
  Crus cerebelli ad medullam, 346
  Crus of diaphragm, 152
  Crus, muscles of, 203
  Crystalline lens, 414
  Cuboid, 82, 84
  Cuneatus, fasciculus, 337, 345, 346
  Cuneiform bones, 70, 80, 84, 85
  Cutaneous nerve, external, 388
  Cutaneus colli, N., 385
    femoralis lateralis, N., 396
    femoris posterior, N., 403
    maximus, M., 93, 434
    medialis, N., 390
  Cystic artery, 302
    duct, 241

  Deciduous teeth, 226
  Deltoid muscle, 156
    ridge, 66
  Demifacets, costal, 3
  Dens, 14, 15
  Dental arteries, 288
    nerves, inferior, 375
  Dentes, 224
  Depressor conchæ, M., 103, 435
  Dermal muscles, 93
  Diaphragm, 151; dissection of, 446
  Diastema, 225
  Diencephalon, 342, 343, 344, 352
  Digastric muscle, 107, 440
  Digestive apparatus, 221
  Digital arteries, 297, 314
  Digital fossa, 79
  Digits, 72
  Directions for dissection, 429
  Disarticulation of skulls, 430
  Dissection of alimentary canal, 449
    blood-vessels, 456
    brain, 464
    circulatory system, 455
    cranial nerves, 465
    diaphragm, 446
    ear, 470
    eye, 469
    ligaments, 431
    lymphatics, 460
    muscles, 433
    nervous system, 461, 465
    pelvic muscles, 446
    respiratory organs, 452
    sense organs, 469
    spinal nerves, 467
    sympathetic system, 465