anatomy forum pelvis done

Gross Anatomy Forum Pelvis & Perineum

Version: 09Apr2009 of 7

Pelvis & Perineum Forum 1. Trace the pudendal nerve (S2-4) and it terminal branches. What structures are innervated? What landmarks are important along the course (ID landmarks)? A: The pudendal nerve is a branch of the sacral plexus and leaves the main pelvic cavity through the greater sciatic foramen. After a brief course in the gluteal region of the lower limb, it enters the perineum through the lesser sciatic foramen. The nerve then passes forward in the pudendal canal and, by means of its branches, supplies the external anal sphincter and the muscles and skin of the perineum. Inferior rectal nerve: This runs medially across the ischiorectal fossa and supplies the external anal sphincter, the mucous membrane of the lower half of the anal canal, and the perianal skin. Dorsal nerve of the penis (or clitoris): This is distributed to the penis (or clitoris). Perineal nerve: This supplies the muscles in the urogenital triangle and the skin on the posterior surface of the scrotum (or labia majora).



2. When performing an episiotomy, what perineal structures are cut? A: Incision made through perineal skin in a midline direction to avoid the anal sphincters and perineal body (muscles attached to central tendon). With posterolateral cut: superficial transverse perineal muscle, bulbospongiosus muscle, skin, Colle’s fascia.

3. What route do you think a surgeon would take when repairing a ruptured bladder? Why? A: Through wall of vagina (suprapubic) in female and abdominal wall (or possibly urethra) in both. The route would depend on the ability to operate in a smaller space (non-abdominal wall incision) as well as other factors such as healing time or appearance of a scar. In relation, the bladder is above the pubic bone. James Lamberg 4. While performing a pap smear what structures can be assessed? A: Speculum is inserted and opened for view of cervix, fornix, external os.

4a. Where are the cells of the pap smear derived? A: Epithelial cells from cervical mucosa; looking for normal cells and dysplastic (abnormal) cells 5. A 10-year-old male presents from an accident where he fell and straddled his bike. Since the time of the accident he has been unable to urinate. What are the potential symptoms for the various forms of urine extravation? What are the boundaries that would dictate where the ruptures in the urethra occurred?



A: Three options: breaks above membranous urethra, Buck’s fascia intact, and both urethra and Buck’s fascia ruptured and contained within Scarpa’s fascia. The common site of rupture is within the bulb of the penis, just below the perineal membrane. The urine extravasates into the superficial perineal pouch and then passes forward over the scrotum beneath the membranous layer of the superficial fascia. If the membranous part of the urethra is ruptured, urine escapes into the deep perineal pouch and can extravasate upward around the prostate and bladder or downward into the superficial perineal pouch. 6. What are the two approaches to performing a hysterectomy? What other structures are potentially affected? A: Laprotomy technique (open technique) and supracervical technique (through umbilicus or vaginal canal). Potentially affected organs include vagina, ovaries, uterus, cervix, ureters, uteral artery, and broad ligament. Removal of ovary would lead to immediate onset of menopause. 7. While performing a cystoscopy what structures can be assessed? A: For viewing trigone, mucous membrane of the bladder, the two ureteric orifices, prostatic urethra, uvula vesicae, and the urethral meatus. 8. List the structures that pass through the pelvic inlet. List the structures that pass through the pelvic outlet. Are there any structures that pass through both? A: Inlet: Rectum, ureters, gonadal vessel, intenal illial vessels, ductus deferens/round ligament, lumbosacral trunk, obturator nerve, hypogastric plexus, sympathetic trunk, lymphatics. Outlet: Anus, urethra , vagina, deep dorsal vein of penis/clitoris, cavernous nerves, inferior rectal nerve, inferior rectal artery, inferior rectal vein. 9. What are the structures that attach to the perineal body? A: Bulbospongiosis, superficial and deep transverse perineal muscles, external anal sphincter, Colle’s fascia, perineal membrane, superior fascia of UGD, deep investing fascia, pubococcygeus. 10. What would you say are the distinguishing features of these two photos?

A: See attached images. The false pelvis is shallow in the female and deep in the male. The pelvic inlet is transversely oval in the female but heart shaped in the male because of the indentation produced by the promontory of the sacrum in the male. The pelvic cavity is roomier in the female than in the male, and the distance between the inlet and the outlet is much shorter.

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The pelvic outlet is larger in the female than in the male. In the female the ischial tuberosities are everted and in the male they are turned in. The sacrum is shorter, wider, and flatter in the female than in the male. The subpubic angle, or pubic arch, is more rounded and wider in the female than in the male. The male pelvis is thicker and heavier than the female pelvis. 11. Uterine prolapse and urinary incontinence can be a direct result from injury to what structures? A: Levator ani muscles, pelvic diaphragm, cervical diaphragm, transverse cervical, pubocervical, and sacrocervical ligaments. Cystocele is sagging of bladder results in bulging of the anterior wall of the vagina. Pubococcygeus can be torn during child birth. 12. Where would you inject anesthetic agent to perform a pudendal nerve block? What landmark(s) would be used to guide the injection? A: Where the nerve cross the lateral aspect of the sacrospinous ligament near its attachment to the ischial spine. The palpable landmark would be the ischial spine (1) or ischial tuberosity (2).

13. A patient of yours has an occlusion of the inferior vesicular artery. What structures would be affected by this occlusion? A: Urinary bladder, ureters, seminal vesicles, vas deferens, prostate, and a little bit of the bulb of the penis via collateral circulation. 14. What would be the effect on micturition if the sacral spinal segments were destroyed? A: S1-S5 parasympathetic innervation and somatics (e.g. pudendal); won’t be able to relax your bladder to urinate, difficulty ejecting urine (bulbospongiosus), structural support (levator ani). 15. In a female patient the superficial inguinal nodes are inflamed, however, there is no sign of infection in any external structures. Where is the most likely site of the infection? Why? A: Near the point where the uterine tube joins the uterus. This has lymph channels that join the round ligament and follow to the superficial inguinal nodes. 16. What structures are in danger in the instance of a pelvic fracture of the superior pubic ramus?



A: Vas deferens, bladder, and vessels, which could tear and fill the pelvic area, pushing other organs to the side. So urine will go to retropubic space, filled with loose (areolar) endopelvic fascia. 17. A patient is shot in the gluteal region with the bullet passing through the great sciatic foramen what structures could potentially be damaged? A: Piriformis muscle, sacrospinous ligament, sacrotuberous ligament, superior gluteal artery and vein, internal pudendal nerve, sciatic nerve, pudendal artery and vein. 18. A patient is complaining about knee pain, after extensive testing and knee examinations, it is determined that there is nothing wrong with the knee…where do you think the problem is and why? A: A hairline fracture of the pelvis. The torso weight is distributed to the lower limbs and if not done properly than there are symptoms seen in the limbs. 19. A female patient has a blockage in her uterine artery. What vessels can provide collateral circulation? A: The ovarian artery, which also supplies the uterus. Also possibly the vaginal artery depending on where the uterine artery is blocked, but mainly ovarian.

anatomy forum pelvis done

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