Prelab Images - Pelvis & Pelvic Viscera

Prelab should consist of reading the lab manual and dissector answers and viewing the dissection video. To begin your study, you may find it useful to look over the Netter's or LWW Atlas images listed below.

Step 1. On the skeleton define the boundaries of the perineum. Examine the peritoneal relationships in the pelvis. (Play movie)

Plate N248 or TG5-03 identifies the pubic symphysis, pubic arch, and the coccyx. The inferior ramus of the pubis and the ramus of the ischium (combine to form the ischiopubic ramus) are labeled in plate N486 or TG3-05. The ischial tuberosity is also labeled in plate N486 or TG3-05 and TG3-04. Plate N380 or TG6-24A and TG6-24B shows the urogenital triangle and anal triangle. Plates N356 or TG6-21A, N357 or TG6-23, and N358 or TG6-21B show the pelvic diaphragm in the female and the male. The pelvic diaphragm will be studied in more detail later. Plate N354 or TG6-05A, TG6-05B, TG6-05CD, and TG6-05EF shows the differences between the male and the female pelvis.

Plates N360 or TG6-08 and N362 or TG6-07 and TG6-13 show the uterus, uterine tubes, ovaries, rectum, rectouterine pouch, and vesicouterine pouch in the female. Plates N361 or TG6-08 and N363 or TG6-07 label the rectum and rectovesical pouch in the male. The broad ligament and the mesosalpinx, mesovarium, and mesometrium that compose the broad ligament are all labeled in plate N371 or TG6-11.

Step 2. Examine the external genitalia of both sexes. (Play movie)

Plate N377 or TG6-25A labels all of the external genitalia in the female (vulva, mons pubis, labia majora, labia minora, frenulum, clitoris, glans, prepuce, vestibule, vaginal orifice, and external urethral meatus). Plate N382 or TG6-25B labels the penis, frenulum, glans, corona of the glans, and the external urethral meatus. The prepuce is labeled in plate N398 or TG6-25B. The dorsum of the penis is not labeled, but is shown in plate N351 or TG6-02. The body (shaft) of the penis is labeled in plate N351 or TG6-25. Plates N387 or TG6-31 and N390 feature the scrotum. The scrotal raphe is shown in plate N398 (unlabeled) as the pink line that divides the scrotum into left and right halves.

Step 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)

To begin the dissection use a sharp scalpel to cut midsagittally through the soft tissues of the pelvis (beginning from the L4 level and continuing downward). Then use a saw to saw through the pubic symphysis, sacrum, and the last two lumbar vertebrae (sawing in the same direction as the original cut). Finally, make a cut on the right side of the cadaver from the body wall to the lumbar vertebrae where you began the midsaggital cut. This will allow you to remove the right side of the pelvis and the right leg. Thoroughly wash all fecal material out of the rectum on both sides. Now you should have a midsagittal view of the pelvis (see plates N360 or TG6-08A and N361 or TG6-08B).

Step 4. Examine the internal features of the rectum. (Play movie)

Plate N393 or TG6-16 shows the rectum, sigmoid colon, and the anal canal. Plates N360 and N361 or TG6-08A, TG6-08B, TG6-15A, TG6-15B, and TG6-15C show the relationship of the rectum to the other pelvic viscera in the female and the male. Plates N393 or TG6-16 and N394 identify the transverse rectal folds and the longitudinal muscle of the rectum. The ampulla of the rectum is the distal part of the rectum that bulges out just before the rectum turns into the anal canal (N394 or TG6-16). Plates N307 or TG5-14, N311 or TG5-28, and N409 show the superior rectal vessels (the superior rectal artery is a branch off of the inferior mesenteric artery and the superior rectal vein drains into the portal system). Plates N409, N410 or TG6-19A, and N412 or TG6-19B show the inferior hypogastric plexus that lies on each side of the rectum. Careful not to destroy this nerve plexus, it will be dissected later.

Step 5. Identify the structures of the anal canal. (Play movie)

Plate N393 or TG6-16 labels the anal canal, anal columns, pectinate line, anal valves, and anal sinuses. Plates N393 or TG6-16 and N394 show the internal and external anal sphincters and longitudinal muscle fibers passing through the external anal sphincter to end in the skin. Plates N398, N399, and N402 or TG6-16A, TG6-17B, and TG5-28 show the blood supply and venous drainage of the rectum (superior, middle, and inferior rectal arteries and veins). Notice in plate N399 or TG5-28 that the superior rectal vein drains into the portal system and the middle and inferior rectal veins drain into the caval system. Plates N410 or TG6-19A or TG6-19B and N411 or TG6-30 show the innervation (autonomic and somatic) of the rectum, which will be considered later. Plates N406 or TG6-33, N407 or TG6-34, and N408 show the lymphatic drainage of the rectum and the anal canal.

Step 6. Remove the peritoneal covering of the bladder and examine. (Play movie)

Plates N360 or TG6-07A, TG6-07B, and N361 or TG6-08A, and TG6-08B and show the peritoneal coverings of the urinary bladder in the male and female. The urachus (median umbilical ligament) is identified in plate N362 or TG5-07A. Plate N366 or TG6-10A and TG6-10B identifies the ureteric orifices, interureteric crest, trigone, and uvula of the bladder. The urethral orifice is not labeled, but it is the point where the bladder empties into the urethra. The blood supply (N402 or TG6-17A, N403 or TG6-17B), innervation (N410 or TG6-19A and TG6-19B), and lymphatic drainage of the bladder (N406 or TG6-33, N407, and N408 or TG6-34) will be considered later.

Step 7. Examine the female genital tract, remove the peritoneum overlying the ovarian vessels. (Play movie)

Plate N360 shows the vesicouterine pouch, rectouterine pouch, and the reflection of the peritoneum onto the rectum. Plates N360 or TG6-08, N369, and N371 all show the uterus. Plate N371 or TG6-11 features the broad ligament (mesosalpinx, mesovarium, and mesometrium). The ovarian ligament (ligament of ovary) and the round ligament are best seen in plate N369 or TG6-11 and TG6-12. Plate N399 considers the development of these ligaments. Plate N371 or TG6-12 labels the suspensory ligament of the ovary, which contains the ovarian vessels (source of these vessels is shown in N400 or TG5-34). Plate N371 or TG6-12 labels the uterine tube, isthmus, ampulla, infundibulum, fimbrae, and ostium. Plates N360, N369, and N371 or TG6-12 all show the ovary. Now strip the peritoneum from the suspensory ligament of the ovary and trace the ovarian vessels to their source (N400 or TG5-34). Next, search through the mesometrium of the broad ligament (N371 or TG6-12) to find the uterine vessels (N400, N402 or TG6-17) from the anterior division of the internal iliac artery. The ureter is shown in plate N400 or TG6-09A and the round ligament is also shown in this plate moving towards the deep inguinal ring. The uterus and its parts (fundus, body, lumen, isthmus, cervix, and cervical canal) are labeled in plate N371 or TG6-12. The vagina and vaginal vestibule are labeled in plate N370 or TG6-11. The cervix (protruding into the vagina), vaginal fornices, and ostium of the uterus are all labeled in plate N371 or TG6-12. The relationship of the vagina to urethra, bladder, and rectum is shown in plate N378 or TG6-08. The perineal membrane is labeled in plate N382 or TG6-11 (with the vagina and urethra passing through it). The vagina is shown passing through the pelvic diaphragm in plates N382 and N370 or TG6-23. The female urethra is shown in plates N382 or TG6-09, N383, and N362 or TG6-10. The pubovesical ligament is labeled in plate N382 or TG6-09. The sphincter urethrae muscle and the membranous portion of the urethra are shown in plates N382 or TG6-09, N383 or TG6-10, and N362. Plate N404 or TG6-11 considers the blood supply and venous drainage of the ovary, uterine tube, uterus, and vagina. Plate N402 or TG6-17 shows the origin of the uterine, vaginal, and internal pudendal arteries. Plate N404 or TG6-29 shows the origin of the perineal artery. Plate N400 or TG5-34 shows the origin of the ovarian artery.

Step 8. Examine the male genital tract, remove endopelvic fascia surrounding seminal vesicles. (Play movie)

Plates N361 or TG6-08 and N362 or TG6-07 and TG6-31 trace the course of the ductus deferens from the testes, over the urinary bladder, and into the seminal vesicles (N384 or TG6-08). Plate N362 or TG5-07 shows the relation of the ductus deferens to the inferior epigastric artery and external iliac arteries. Plate N361 or TG6-08 shows its relation to the medial umbilical ligament, ureter, and seminal vesicle. Plate N384 or TG6-14 labels the ampulla of the ductus deferens. Plate N361 or TG6-08 labels the rectovesical pouch. The location of the seminal vesicle is shown in plates N361 or TG6-14 and N363 or TG6-07. Plate N384 or TG6-14 shows the relation of the seminal vesicle to the ductus deferens, ampulla, and bladder. The ejaculatory duct is labeled in plate N384 or TG6-10. Plate N365 or TG6-09 shows the puboprostatic ligament (pubovesical ligament in the female). Plate N361 or TG6-15 shows the relationship of the prostate to the bladder and rectum. Plate N359 or TG6-10 shows the prostate surrounding the urethra in the urogenital hiatus (oval shaped area where the pelvic diaphragm is incomplete). The prostatic urethra, urethral crest, prostatic sinus, and colliculus seminalis (seminal colliculus) are all shown in plate N384 or TG6-10. Plates N361 or TG6-09 and N384 or TG6-10 show the sphincter urethrae muscle just inferior to the prostate. Plate N384 or TG6-09 labels the prostatic, membranous, and penile (spongy) parts of the male urethra.

Step 9. Identify the structures of the testis, epididymis, and spermatic cord. (Play movie)

Plate N387 or TG6-31 and TG5-10 reviews the contents of the spermatic cord (ductus deferens, pampiniform plexus of veins, and testicular artery). Plates N387 or TG6-32 and N390 show the testis and the tunica vaginalis testis (parietal and visceral layers). Plate N399 reviews the descent and development of the testis. The testes are sectioned in a sagittal plane in plate N390 or TG6-32 and the tunica albuginea and convoluted seminiferous tubules are shown.