Re: Pelvic Musculature

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: : Pelvic Musculature and Fascia: : : 1. The pelvis actually consists of 3 bones. Explain and elaborate on the different parts of the pelvis. Where do all 3 bones meet? : *Ilium (do not confuse with ileum (most distal portion of sm. intestine)). Most superior bone of fused pelvis. Notable structures include: ala, iliac crest, iliac fossa, ASIS, AIIS, PSIS,& iliopectineal line : *Ischium - inferolateral bone of fused pelvis. Notable structures include ischial tuberosity, ischial spine, body, & superior & inferior rami. Contributes to obturator foramen : *Pubis - inferomedial bone of fused pelvis. Notable structures include pectin pubis, pubic tubercle, body, & superior & inferior rami. Note: 1)pubic symphysis joins two pubic bones at midline; 2) subpubic angle differs between males and females . Contributes to obturator foramen. : The fused pelvic bones meet at the acetabulum : : 2. Define the pelvic diaphragm. Is the pelvic diaphragm part of the levator ani, or is the levator ani part of the pelvic diaphragm? Is the pelvic diaphragm part of the coccygeus (ischiococcygeus) muscle? Is the piriformis part of the pelvic diaphragm? : The pelvic diaphragm is bordered laterally by the arcus tendineus, anteriorly by the bodies of the pubic bones, and posteriorly by the sacrum and attachments of the piriformis muscle. It spans the pelvic brim, separating the true pelvis superiorly from the false pelvic inferiorly. It is comprised of the coccygeus muscle and the levator ani muscle group. The levator ani muscle group contains the puborectalis, the pubococcygeus, and the iliococcygeus. The piriformis is not considered part of the pelvic diaphragm. The pelvic diaphragm is the inferior border of the true pelvic and the superior border of the perineum. The pelvic diaphragm is important for resisting increased intra-abdominal pressure from sneezing, coughing, vomiting, forced expiration, and heavy lifting. The pelvic diaphragm also has an important role in defecation: the puborectalis muscle 'slings' around the rectum and, in tonic contraction, crimps the rectum anteriorly to 90 degrees, preventing untimely defecation. Fascia associated with the pelvic diaphragm includes: 1)the arcus tendineus (condensed obturator fascia attached anteriorly to the pubic symphysis and posteriorly to the ischial spine) from which the iliococcygeus muscle originates; 2) the anococcygeal raphe (extending between the coccyx and the margin of the anus). Additionally, the urogenital hiatus, located on the anterior midline and bordered by the medial fibers of the puborectalis, permits passage of the urethra from the pelvic cavity into the perineum and in females, the vagina. : : 3. What is the "puborectal sling", and what is its function? : The puborectal sling is formed by the U-shaped muscle fibers of the puborectalis muscle that are continuous between the posterior aspects of the right and left pubic bodies. THe fibers form the margin of the urogenitial hiatus, passing anterior to the anorectal junction and the anococcygeal raphe. This muscular sling is typically tonically contracted and crimping the rectum at 90 degrees to prevent defecation. Relaxation of the puborectalis muscle loosens the sling, permits the rectum to assume a vertical, uncrimped position, and allows the passage of fecal matter through the anus. : : 4. What is the true and false pelvis. : The true pelvis is associated with the pelvic cavity and is inferior to the pelvic brim. The false pelvis is associated with the abdominal cavity and is superior to the pelvic brim but the superior limit f the false pelvis is a line between the ala of the ilia. The pelvic brim is marked by the pubic symphysis anteriorly, the sacral promentory posteriorly, the iliopectineal and iliac arcuate lines (immediately inferior to the iliac fossa and the iliacus muscle) laterally. : : : 5. Discuss differences between the male and female pelvis. : Numerous. : In females, the pelvis is made of bones that are delicate, thin, and light. The false pelvis is shallow with shallow iliac fossa, wide iliac ala, and an oval to round, wide superior pelvic inlet. The true pelvis is wide and shallow and as paired with the false pelvis creates a cylinder for the passage of the fetus. The female pelvis also has a small acetabulum, an oval obturator foramen, and a wide (>80degrees) subpubic angle. : The male pelvis is made of thicker and heavy bones. The false pelvis is deep, with near-vertical iliac ala and a narrow, heart-shapped pelvic inlet. The true pelvis is narrow, deep, and tapering to a small pelvic outlet (no need to pass a fetus). The male pelvis has a large acetabulum, a round obturator foramen, and a narrow (<70degrees) subpubic angle. : : 6. Discuss the membranous urethra. : The membranous urethra is localized with the deep perineal pouch and passes through external urethral sphincter in the urogenitial diaphragm. It is the least distensible part of the urethra. In males the membranous urethra is an intermediate part (owing to the presence of the prostate and henceforth the prostatic urethra, in females it is the proximal part. : Rupture of the membranous urethra can have several presentations that depend of collateral injuries. If only the membranous urethra is ruptures, urine with extravasate into the deep pouch and then superiorly through the urogenitial hiatus and distribute extraperitoneally around, in males: the bladder and the prostate (contained within continuous perivisceral pelvic fascia) or, in females, the bladder. If the membranous urethra is ruptured and the superior fascia of the UG diaphram is compromised, then urine will extravasate into the anterior recess of the ischiorectal fossa. However, if the inferior fascia of the UG diaphragm is comprised, urine will extravasate into the superficial perineal pouch. : : 7. Does the prostatic venous plexus lie deep to the perivisceral fascia? : No. The prostatic venous plexus lies within to the periprostatic fascia. Deep to the periprostatic fascia is the capsule of the prostate. The PVP drains into the internal iliac veins. : : 8. Discuss the structure, innervation, and vasculature - and fascia releationships - of the prostate gland. : The prostae ("protector", "one who stands before") gland is the largest accessory gland of the male reproductive system. It is walnut-shaped with a gentle concavity in the posterior aspect that is filled with Fascia of Denonvilliers and adjacent to the ampulla of the rectum. The levator ani muscles lie inferior and lateral to the prostate. The prostatic urethra (proximal urethra in males) passes through the prostate. Only two-thirds of the prostate is glandular and is responsible for contributing approximately 20% of the volume of male ejaculate; the remaining one-third is fibromuscular. The prostate is ensheathed with perivisceral pelvic fascia except on the superior aspect which abuts the caudal margin of the bladder. The perivisceral fascia is continuous anterolaterally with the puboprostatic ligament and blends posteriorly with the rectovescial septum. Inferior to the prostate gland is the urogenitial diaphragm. Deep to the periprostatic fascia is the tough, fibrous capsule of the prostate. Within the prostate gland the prostatic ducts convey prostatic fluid (thin and milky, partly responsible for activating sperms) centrally into the prostatic sinuses of the urethra. The prostatic arteries usually branch from the inferior vesical arteries but may also receive contributions from the internal pudendal and middle rectal arteries. The prostate is innervated by post-synaptic sympathetic and parasympathetic fibers from the hypogastric and pelvic plexuses (sympathetic from lumbar splanchnics, parasympathetic from S2 and S3) : : 9. What is a transverse rectal fold? : : 10. What is the relationship of the peritoneum to the rectum? : : 11. Define the vasculature to the rectum and anus. : : 12. Discuss the structure of the anal canal. : : 13. Discuss hemorrhoids above and below the pectinate line. : : 14. Define the structure of the bladder - include innervation and vasculature. : : 15. What is the arcus tendineus? : : 16. Are the muscles of the pelvic diaphragm skeletal or smooth? : : 17. What is the innervation to the pelvic diagragm? Is this autonomic or somatic? : : 18. What is the difference between the seminal colliculus and the urethral crest? : : 19. What is the trigone of the bladder? : : 20. Is the detrusor muscle part of the trigone of the bladder? : : 21. Define the prostatic venous plexus. : : 22. Does the ischiorectal fossa contain perivisceral fascia? : : 23. What is the relationship of the anterior recess of the ischiorectal fossa to the posterior recess of the ischiorectal fossa? : : 24. Discuss a breakage of the membranous urethra at the deep pouch that penetrates the superior fascia of the U.G. diapraghm and define the location of urine, and contrast this with the location of urine in a break through the inferior fascia of the U.G. diaphragm. : : 25. Will urine in the ischiorectal fossa drain into the superficial pouch? : : 26. Discuss the boundaries and contents of the ischiorectal fossa. : : 27. Discuss the boundaries and contents of the superficial pouch. : : 28. Discuss the boundaries and contents of the deep pouch.

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