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Lab Manual - Pelvis & Pelvic Viscera |
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Assignments:
- Before lab:
- Download and review the Lab Overview PowerPoint.
- Review the Prelab Learning Module.
- Review the Steps of Dissection and Dissection Videos.
- During lab:
- Follow the steps of the dissection procedure in the Lab Manual (this page).
- Be certain to identify all of the Review Items.
- After lab:
- Read the Dissector Answers to cover the Learning Objectives for this lab.
- Read the Clinical Case for this lab.
- Review the Practice Questions for this lab.
Learning Objectives:
Upon completion of this session, the student will be able to:
- 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.
- Identify the superficial features of the external genitalia.
- Recognize the features of the rectum that differentiate it from the colon.
- Describe the point at which the anal canal begins.
- Describe the internal features of the anal canal, and determine the point at which its lining changes from cutaneous to mucosal.
- Recall the lymph node groups that drain the anal canal.
- Organize blood and nerve supply to the anal canal.
- Recognize the urinary bladder in either its expanded or contracted position, and determine the extent of its peritoneal covering.
- Identify the internal orifices of the bladder and differentiate the trigone region from the rest of the bladder lining.
- Describe the relationships of the bladder to other pelvic organs in both sexes.
- Describe the normal position and relationships of all organs of the reproductive tracts in both sexes and the role of each in reproductive processes.
- Describe the broad ligament and differentiate its parts.
- Identify the ovary and discuss the functional significance of its ligaments.
- Demonstrate the uterine tube and its subdivisions.
- Identify the uterus and its subdivisions and demonstrate the continuity of its lumen with that of the uterine tubes and the vagina.
- Differentiate between the internal and external os of the cervix.
- Identify the vagina, and note the angle formed at its junction with the uterus.
- Trace the entire course of the ductus deferens and identify its ampulla; note its relationship to the ureter.
- Identify the seminal vesicle and demonstrate the formation and course of the ejaculatory duct.
- Identify the prostate gland and describe the special features of the prostatic urethral wall.
- Identify the testis, its coverings, and tubules, and account for the difference in location between gonads in the two sexes.
- Demonstrate the epididymis and its subdivisions.
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.
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 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)
Before proceeding with the midsagittal section of the pelvis below, 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. Now continue with dissection procedures on either male or female, but be sure to review all structures on a cadaver of the opposite sex as well.
3. Make a midsagittal section of the pelvis of the cadaver, removing the right pelvis and lower limb at the 4th lumbar vertebra. (Play movie; View images: N 360, 361, TG 6-08A, 6-08B)
Make a careful midsagittal section of the pelvis. Cut all soft tissues, including all genital organs, with a sharp scalpel as close to the actual midline as possible, and use the saw to cut the pubic symphysis, sacrum and last two lumbar vertebrae. On the right side cut half way through the disk between the third and fourth lumbar vertebrae to meet the sagittally-sectioned pelvis. This will keep the posterior abdominal wall intact and continuous with the left half of the pelvis and one lower limb. Thoroughly wash all fecal material out of the rectum on both sides.
4. 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: Thoroughly wash out the specimen. 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. Trace the superior rectal vessels. Be careful not to destroy the inferior hypogastric plexus, which lies on the side of the rectum.
Barium enema 5. 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. On the cut surface of the sectioned anal canal, note the internal anal sphincter. Trace fibers of the longitudinal muscle through the external anal sphincter to end in the skin. 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.
6. 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 7. Examine the female genital tract, remove the peritoneum overlying the ovarian vessels. (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 the sagittally-sectioned 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?
Pull the uterus toward the mid-line and 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.
Hysterosalpingogram Ovary: Examine the ovary. Consider size, attachments, covering, relations to broad ligament and uterine tube. Slice one of them longitudinally and examine for follicles, etc.
Strip the peritoneum from the suspensory ligament of the ovary on one side and trace the ovarian artery and vein (source?). What is its complete area of distribution? Continue stripping the peritoneum from both surfaces of the broad ligament on the same side as above and locate the uterine artery and veins near its base. Trace to the uterus, noting branches and point of junction at the uterine wall. Locate the ureter (relation to uterine artery); trace it to the bladder and posteriorly to the brim of the pelvis, noting course, relation to peritoneum and blood supply. 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. What structure supports the uterus?
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? Locate relation to pelvic diaphragm and perineal membrane.
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.
8. 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 9. 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?