Anatomy of the Cat

by Jacob Reighard; H. S. Jennings

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 (p[p. 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]).