Lab Manual - Pelvis & Pelvic Viscera

Learning Objectives:

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

  1. Trace the continuity of the abdominal peritoneum with that of the pelvic cavity, and identify the peritoneal pouches of the pelvic floor in both sexes. (explanation)
  2. Identify the superficial features of the external genitalia. (explanation)
  3. Recognize the features of the rectum that differentiate it from the colon. (explanation)
  4. Describe the point at which the anal canal begins. (explanation)
  5. Describe the internal features of the anal canal, and determine the point at which its lining changes from cutaneous to mucosal. (explanation)
  6. Recall the lymph node groups that drain the anal canal. (explanation)
  7. Organize blood and nerve supply to the anal canal. (explanation)
  8. Recognize the urinary bladder in either its expanded or contracted position, and determine the extent of its peritoneal covering. (explanation)
  9. Identify the internal orifices of the bladder and differentiate the trigone region from the rest of the bladder lining. (explanation)
  10. Describe the relationships of the bladder to other pelvic organs in both sexes. (explanation)
  11. Describe the normal position and relationships of all organs of the reproductive tracts in both sexes and the role of each in reproductive processes. (explanation)
  12. Describe the broad ligament and differentiate its parts. (explanation)
  13. Identify the ovary and discuss the functional significance of its ligaments. (explanation)
  14. Demonstrate the uterine tube and its subdivisions. (explanation)
  15. Identify the uterus and its subdivisions and demonstrate the continuity of its lumen with that of the uterine tubes and the vagina. (explanation)
  16. Differentiate between the internal and external os of the cervix. (explanation)
  17. Identify the vagina, and note the angle formed at its junction with the uterus. (explanation)
  18. Trace the entire course of the ductus deferens and identify its ampulla; note its relationship to the ureter. (explanation)
  19. Identify the seminal vesicle and demonstrate the formation and course of the ejaculatory duct. (explanation)
  20. Identify the prostate gland and describe the special features of the prostatic urethral wall. (explanation)
  21. Identify the testis, its coverings, and tubules, and account for the difference in location between gonads in the two sexes. (explanation)
  22. Demonstrate the epididymis and its subdivisions. (explanation)

Readings and Modules:

Procedure:

1. 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.

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 uterus, uterine tubes, and ovaries in the female and rectum in both sexes. Notice how these structures and the associated peritoneum form the rectouterine and vesicouterine pouches in the female and rectovesical pouch in the male.

The peritoneal reflection onto the uterus, uterine tubes, and ovaries from the lateral pelvic wall is called the broad ligament. Observe its three component parts: the mesosalpinx associated with the uterine tubes, the mesovarium associated with the ovary, and the mesometrium contacting the uterus.

2. Examine the external genitalia of both sexes. (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 both sexes: Female external genitalia: vulva, mons pubis, labia majora and their anterior and posterior commissures; labia minora and associated frenulum; clitoris and its glans, and prepuce; vestibule and its vaginal orifice and external urethral meatus. Male external genitalia: penis, prepuce, frenulum, glans, corona, external urethral meatus, body and dorsum of the penis, scrotum, and scrotal raphe.

For the following procedures and objectives, unless otherwise noted, please use plastinated and prosected specimens and models.

3. Examine the internal features of the rectum. (Play movie; View images: N 307, 311, 360, 361, 393, 394, 409, 410, 412, TG 5-14, 5-28, 6-08A, 6-08B, 6-15A, 6-15B, 6-15C, 6-16, 6-19A, 6-19B)

Rectum: Define the rectum. Observe its continuity with the sigmoid colon and the anal canal. Note relations to other pelvic organs in both male and female. Examine characteristics of rectum: the longitudinal musculature, the transverse rectal folds, the ampulla. In your cadaver, trace thesuperior rectal vessels from their source to the rectum.

Barium enema

4. Identify the structures of the anal canal. (Play movie; View images: N 393, 394, 398, 399, 402, 406, 407, 408, 410, 411, TG 5-28, 6-16, 6-17A, 6-17B, 6-19A, 6-19B, 6-30, 6-33, 6-34)

Anal canal: Define and note the flexure between rectum and anal canal. What muscle assists this flexure? In the mucosa, define the anal columns, pectinate line (significance? ), anal valves, anal sinuses. Look for the internal and external anal sphincters. Consider various sources of the blood supply, the collaterals between portal and caval venous drainage, and the different functions of the autonomic and somatic innervation. Consider the pattern of lymphatic drainage and the node groups that receive lymphatic drainage from the rectum and anal canal.

5. Exam the bladder. (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: On your cadaver, observe the peritoneal coverings of the urinary bladder. Make a small midline incision in the “floor” of the vesicouterine pouch in the female cadaver or in the rectovesical pouch in the male cadaver. Use scissors to extend the incision of the peritoneal covering (be careful to only incise the peritoneal layer) about 2 inches in each direction toward the sidewalls. Starting at the cut edge carefully peal the peritoneum from the back of the bladder to expose the lower half of the bladder. Try to identify the ureters as they pass from the posterior wall under the peritoneum and into the bladder. On plastinated and prosected specimens and models, 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

6. Examine the female genital tract. (Play movie; View images: N 360, 362, 369, 370, 371A, 371B, 378, 382A, 382B, 383, 399, 400, 402, 404A, 404B, TG 5-34, 6-08, 6-09A, 6-10, 6-11, 6-12, 6-17, 6-23, 6-29)

On a plastinated specimen, trace the peritoneum from the ventral abdominal wall; examining the vesicouterine pouch and its manner of reflection from the bladder to the uterus (what part of uterus?). Trace the peritoneum across the uterus and define the rectouterine pouch. Note peritoneum on the posterior wall of the vagina. From what point does the peritoneum reflect to the rectum? Significance?

In the female cadaver or a plastinated specimen, define the broad ligament and its parts: mesosalpinx, mesovarium, and mesometrium. Within the broad ligament, locate the ovarian ligament and the round ligament of the uterus. Consider development and continuities. Locate and define the peritoneal fold called the suspensory ligament of the ovary. What does it contain?

Uterine tube: Examine the uterine tube; define the isthmus, ampulla, infundibulum, fimbriae, and ostium. Note continuity with uterus, relations and attachment to ovary. This can be done on female cadavers as well as on plastinated specimens and models. On plastinated specimens, be sure to examine these structures in specimens with the peritoneum (i.e., broad ligament) intact as well in specimens with the peritoneum removed.

Hysterosalpingogram

Ovary: Examine the ovary. Consider size, attachments, covering, relations to broad ligament and uterine tube. On a female cadaver, slice an ovary longitudinally and examine for follicles, etc.

Again, identify suspensory ligament of the ovary and trace the ovarian artery and vein on each side (source?). Trace the round ligament from the uterus (attachment? ) to the deep inguinal ring.

Uterus: Examine the uterus and define its parts: fundus, body, its lumen (cavity) isthmus, cervix, and cervical canal. Note shape, size, and flexure.

Vagina: Examine the vagina and the structure of its wall. Consider differences between vagina and vaginal vestibule. Examine the intravaginal cervix, the ostium of the uterus, and fornices of the vagina. Note relations to urethra, bladder, and rectum. Significance?

Fetus

Explore the female urethra and note length, sphincter muscle, relation to vagina. Note specifically the relation of the orifice to the anterior vaginal wall. Significance? Where the neck of the bladder meets the pelvic diaphragm and posterior side of the pubis, identify the pubovesical ligament. Examine the sphincter urethrae muscle, and the membranous portion of the urethra.

Consider the blood supply and venous drainage of the ovary, uterine tube, uterus, vagina.

7. 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: On a male cadaver, remove the endopelvic fascia from the posterior surface of the lower bladder that was exposed by reflecting the peritoneum earlier, and expose the seminal vesicle, noting its relation to the ductus deferens, the ampulla, and bladder. Appreciate that the ampulla and the duct of the seminal vesicle 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 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, especially in plastinated specimens.

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

Male urethrogram
Obstructed ureter

8. On a male cadaver, 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 and examine its transition to ductus deferens. Where does this occur?