Lab Manual - Male Reproductive Anatomy

Assignments:

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Trace the skeletal and ligamentous boundaries of the perineum, and define the anal and urogenital triangles.
  2. Identify the superficial features of the external genitalia.
  3. Describe the structure, contents, and course of the pudendal canal.
  4. Trace the branching pattern of the internal pudendal vessels and the pudendal nerve.
  5. Identify the parts of the male urethra.
  6. Identify the components of the external genital organs and give the homologues in each of both sexes.
  7. Describe structure and function of the erectile bodies.
  8. Identify the muscles and fasciae of the perineum and their functions.
  9. Trace the nerve and blood supply to the external genital organs and the muscles of the perineum.
  10. Trace the lymphatic drainage of the perineum.
  11. Trace the continuity of the abdominal peritoneum with that of the pelvic cavity.
  12. Describe the relationships of the bladder to other pelvic organs.
  13. Identify the testis, its coverings, and tubules, and account for the difference in location between gonads in the two sexes.
  14. Trace the entire course of the ductus deferens from the epididymis to its ampulla; note its relationship to the ureter.
  15. Identify the seminal vesicle and demonstrate the formation and course of the ejaculatory duct.
  16. Identify the prostate gland and describe the special features of the prostatic urethral wall.

Procedure:

1. Examine the bony pelvis. (Play movie; View images: N 248, 352, 486, 503, TG 3-04, 3-05, 3-07, 6-03, 6-06A, 6-06B)

Examine the bony pelvis and identify the obturator foramen and groove, the greater sciatic notch (foramen), spine of the ischium, the lesser sciatic notch (foramen), ischial tuberosity. Locate the sacroiliac joint. Review how the sacrotuberal and sacrospinal ligaments help to form the greater and lesser sciatic foramina.

2. Review the bony landmarks. Examine the peritoneal relationships in the pelvis. (Play movie; View images: N 248, 354, 356, 357, 358, 360, 361, 362, 363, 371, 380, 486, TG 5-03,3-04, 6-05A, 6-05B, 6-05CD, 6-05EF, 6-07A, 6-07B, 6-08A, 6-08B, 6-11, 6-13, 6-21A, 6-21B, 6-23, 6-24A, 6-24B)

On the skeleton define the bony landmarks of the perineum: pubic symphysis, pubic arch, inferior ramus of the pubis and the ramus of the ischium (together known as the ischiopubic ramus), the ischial tuberosities, and the coccyx. Define the urogenital triangle and the anal triangle. Note that the two triangles do not lie on the same plane.

Although it is not well seen at this time and will be studied in detail later, understand that the pelvic viscera are supported by the muscles comprising the pelvic diaphragm.

Examine male and female bony pelves and determine different characteristics of each. Note the difference between male and female in the subpubic angle, the angle formed by the pubic arch. Other sex differences in the pelvic skeleton? Now continue with dissection procedures for either male or female, but be sure to review all structures on a cadaver of the opposite sex as well.

Bony structures of the pelvis

Observe the peritoneal relationships in the pelvis and identify the rectum. Notice how these structures and the associated peritoneum form the rectouterine and vesicouterine pouches in the female and rectovesical pouch in the male.

3. Remove the peritoneal covering of the bladder and examine. (Play movie; View images: N 360, 361, 362, 366, 402, 403, 406, 407, 408, 410, TG 6-07A, 6-07B, 6-08A, 6-08B, 6-10A, 6-10B, 6-17A, 6-17B, 6-19A, 6-19B, 6-33, 6-34)

Urinary bladder: Observe peritoneal coverings of the urinary bladder. Note the different reflection in male and female. Remove the peritoneum and identify the urachus (median umbilical ligament). Examine the musculature of the bladder wall and identify the ureteric orifices, the interureteric crest, the urethral orifice, and the trigone. In the male look for a uvula. Blood supply, innervation and lymphatic drainage of the bladder will be exposed in a later dissection.

Urinary bladder

4. Examine the male genital tract, remove endopelvic fascia surrounding seminal vesicles. (Play movie; View images: N 352, 359, 361A, 361B, 362, 363, 365, 384A, 384B, TG 5-07, 6-07, 6-08, 6-09, 6-10, 6-14, 6-15, 6-31)

Ductus deferens (vas deferens): Trace, and note structure, course and relations to testis. Review course through spermatic cord and inguinal canal. After it passes through the deep inguinal ring, trace under the peritoneum and note relations to inferior epigastric artery, external iliac vessels, medial umbilical ligament, the ureter and the seminal vesicle. Define the ampulla of the ductus deferens. Are any of these structures covered by peritoneum? What is the rectovesical pouch?

Seminal vesicle: Remove the endopelvic fascia from the posterior surface of the bladder and expose the seminal vesicle, noting its relation to the ductus deferens, the ampulla, and bladder. Note the ureter and its point of entrance to the bladder; trace it through the pelvis and note its relation to the peritoneum and location as it enters the pelvis. Examine the junction of the ampulla and the duct of the seminal vesicle as they unite to form the ejaculatory duct. Open the seminal vesicle and examine its structure.

Vasogram

Prostate: Examine the prostate gland and attachments to the pubis via the puboprostatic ligament. Note relation of prostate to bladder, urogenital hiatus and rectum (ampulla). Trace the course of the ejaculatory duct. In the prostatic urethra, examine the urethral crest, prostatic sinus, colliculus seminalis and note specifically the openings of the ejaculatory ducts.

Examine the sphincter urethrae muscle around the lower portion of the prostate and proximal part of the urethra. The muscle may be difficult to distinguish.

Review the urethra and determine prostatic, membranous, and penile (spongy) parts.

Male urethrogram
Obstructed ureter

5. Examine the external genitalia in the male. (Play movie; View images: N 351, 377, 382, 387A, 387B, 390, 398, TG 6-02, 6-25A, 6-25B, 6-31)

Identify the external genitalia of the male: penis, prepuce, frenulum, glans, corona, external urethral meatus, body and dorsum of the penis, scrotum, and scrotal raphe. Be sure to review all structures on a female cadaver as well.

6. Identify the structures of the testis, epididymis, and spermatic cord. (Play movie; View images: N 387, 390, 418, TG 5-10, 6-31, 6-32)

Review the major structures of the spermatic cord: ductus deferens, pampiniform plexus of veins, and testicular artery (source?).

On the testis locate the tunica vaginalis testis. Incise along its anterior border. Explore the cavity and parietal and visceral parts of membrane. Review development and descent of testis. Section one testis in the sagittal plane. Determine the extent of coverage of the testis by the tunica vaginalis. Identify the tunica albuginea and lobules of convoluted seminiferous tubules.

Epididymis: Define head, body and tail; section and examine its transition to ductus deferens. Where does this occur?

7. Skin the ischioanal fossa and remove the fat. Identify the sacrotuberal and sacrospinal ligaments and the inferior rectal nerves and vessels. (Play movie; View images: N 353, 357, 358, 359, 377, 379, 380, 381, 395, 402 403, 404, 405, 411, 413, 502, 503, TG 3-07, 3-26, 6-06, 6-15A, 6-15B, 6-15C, 6-23A, 6-23B, 6-24A, 6-24B, 6-26A, 6-26B, 6-28, 6-29A, 6-29B, 6-30A, 6-30B)

Remove the skin from the anal triangle. Care should be taken when skinning around the anus because the external anal sphincter muscle is in contact with the skin. Clean and identify the external anal sphincter.

Using blunt dissection through the fat of the ischioanal (ischiorectal) fossa, locate the inferior rectal vessels and nerves, supplying the external anal sphincter. On the lateral side, follow the walls of the ischioanal fossa and remove all of the fat within the fossa. To do this, identify the inferior border of the gluteus maximus muscle and the ischial tuberosity and follow these surfaces deeply within the ischioanal fossa until the fat wedge is free. Note how gluteus maximus overhangs the ischioanal fossa. Reflect the fibers of gluteus maximus that originate from the sacrotuberal ligament. Define all boundaries of the ischioanal fossa. Note that the lateral wall is the fascia of the obturator internus muscle, and cut the sacrotuberal ligament from its attachment on the ischial tuberosity. Beneath the sacrotuberal ligament, identify the sacrospinal ligament and the greater and lesser sciatic foramina.

8. Identify the pudendal canal and pudendal neurovascular bundle. (Play movie; View images: N 402, 403, 404, 405, 410, 411, 413, 497, 499, 503, TG 3-25A, 3-25B, 3-26, 6-17A, 6-17B, 6-19, 6-29A, 6-29B, 6-30)

Identify the pudendal neurovascular bundle passing around the sacrospinal ligament. Pick up the inferior rectal vessels and nerves, and gently pull toward the midline. This tension will elevate the wall of the pudendal canal so that it may be visualized. Open the canal and identify the pudendal nerve, the internal pudendal artery and veins. Note how far (deep) this canal is from the tip of the ischial tuberosity.

9. Skin the urogenital triangle. Identify the pudendal neurovascular branches. Clean the erectile bodies and reflect them from their attachments on one side. Identify the perineal membrane and sphincter urethrae m. (Play movie; View images: N 265, 266, 359, 362, 364, 365, 379A, 379B, 380, 381A, 381B, 382A, 382B, 383, 385A, 385B, 387, 404, 405A, 405B, 407, 411, TG 5-02, 5-37, 6-09A, 6-09B, 6-10, 6-26, 6-27, 6-28, 6-29, 6-30, 6-31A, 6-31B, 6-32, 6-33, 6-34)

Remove the skin from the penis, scrotum and perineum laterally to the ischiopubic ramus. Note that the subcutaneous tissue of the penis and scrotum contains no fat. In the scrotum this layer, the tunica dartos scroti, contains smooth muscle, often giving it a pinkish color. Pull the half scrotum, with its contained testis, toward the ventral abdominal wall, revealing the complete perineum and the ventral surface of the penis.

The subcutaneous tissue of the perineum consists of a fatty and a membranous layer. Carefully reflect both to one side, and continue reflecting from the shaft of the penis. Within the subcutaneous tissue locate posterior scrotal nerves, arteries and veins (branches of the perineal nerve from pudendal nerve and internal pudendal artery and vein, respectively).

Dissect the ischiocavernosus and bulbospongiosus muscles and note how the deep fascia of these muscles completely invests the shaft of the penis (deep penile fascia). Remove this muscular fascia to reveal the ischiocavernosus and bulbospongiosus muscles covering the crura and bulb of the penis. Reflect one ischiocavernosus muscle and expose the crus of the corpus cavernosum penis. Reflect the bulbospongiosus muscle from the midline, noting the manner in which the muscle covers the bulb of the corpus spongiosum and encircles the root of the penis. Do you find muscular branches (deep) of the perineal nerves? Identify and trace the corpus spongiosum, its bulb, and at the tip of the penis, the glans. Trace the corpora cavernosa penis, noting how the right and left unite to form the shaft of the penis. On the dorsum of the penis locate and identify the deep dorsal vein, and the dorsal arteries and nerves. On one side, cut the penis transversely through the shaft and identify the structure and relationship of the erectile bodies and the tunica albuginea (note differences between corpus spongiosum and cavernosum). Note central or deep artery of penis. Source?

Cut the crus of the penis from the ischiopubic ramus on one side, and free the bulb on this side from its attachment to the perineal membrane. As you do this, try to identify the deep artery of the penis and the artery to the bulb. In midsagittal section, examine the penile (spongy) urethra, its bulb and navicular fossa. Crossing between the arcuate pubic ligament and the anterior border of the perineal membrane is the deep dorsal vein of the penis, while the dorsal arteries and veins of the penis pass through the anterosuperior portion of the perineal membrane. Source or drainage of each?

Now examine the perineal membrane, its extent and attachments. Consider its function. Examine the sphincter urethrae muscle. What gland is embedded in this muscle (in the male)? What are the bulbourethral glands? Review the parts of the male urethra (prostatic, membranous, and spongy or penile).