Part 99

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.