Ischiococcygeus Muscle 1p4v70

Clinical Human Anatomy Class of 2009 Coop November 14, 2005 Lecturer: Dr. Kuhlmann

Pelvis and Perineum 1 Dr. Kuhlmann began by asking us to use the notes as an outline and listen to the lecture. His lecture contained slides that were either from old Netter editions or other textbooks. He said that he would start each class with a review of the previous lecture then end with a clinical correlation. Also, he said that he would be in the inner lab to discuss the prosections of the pelvis. This Coop contains portions of the 2007 Coop with additions. Bony Pelvis [Netter 240,468,340] The bony pelvis is made up of 4 bones: the sacrum (S1-S5), coccyx, and (2) innominate (ox coxal or hip bone). The hip bone is made up of the ilium, ischium, and pubic bone. Spaces and planes [Netter 340] 1) true pelvis - below the iliopectineal line which contains and protects the lower portion of the GI, GU(genitourinary), and internal reproductive organs. 2) false pelvis - above the iliopectineal line. little clinical importance. Look down into the pelvis: the portion of the pelvis below the "ring" is the true pelvis, that portion on top is the false pelvis. Ligaments [Netter 340] The sacrospinous ligament and sacrotuberous ligament form the greater sciatic foramen and lesser sciatic foramen. The sacrospinous sacrospinous ligament and sacrotuberous ligament and sacrotuberous ligament also prevent rotation of the sacrum as this s the weight of the vertebral column. The obturator canal or space is formed by the obturator membrane in the obturator foramen. The obturator nerve, artery, and vein through the obturator canal. Pelvic planes [Netter 342] The plane of the pelvic inlet is a plane drawn from the tip of the sacral promontory to the superior edge of the pubic symphysis. The plane of the pelvic outlet is a plane drawn from the end of S5 to the inferior edge of the pubic symphysis. These two planes are measured (obstetrical conjugate) to determine the type of pelvis a woman has and to see if it is adequate for delivering a child. Sex differences [Netter 342] The male pubic arch is less than 90 degrees, while the female pubic arch is greater than 90 degrees. Dr. Kuhlmann also said if you were to pour cement into the pelvis, you would see the male pelvis cause the flows to converge, while in the female pelvis flows would diverge. Muscular Pelvis [Netter 343-346] 1) The pelvic diaphragm creates two spaces: the intra-pelvic (visceral) and the ischiorectal space.

A. The intra-pelvic (visceral) space is superior to the pelvic diaphragm. The ischiorectal space (fossa) is inferior to the pelvic diaphragm and posterior to the urogenital diaphragm. The ischiorectal fossa is filled with fat and covered by the gluteus maximus muscles. B. Muscles of the pelvic diaphragm are the levator ani muscles and ischiococcygeus (coccygeus) muscle. 1. Levator ani muscles are the main part of the pelvic diaphragm. a. Puborectalis m.: forms a sling, important for maintaining rectal continence b. Pubococcygeus m.: main part of levator ani c. Iliococcygeus m. (Innervation to the levator ani is from the perineal branches of the third and fourth sacral nerves.) 2. Ischiococcygeus muscle (Innervation from S4,5) Note: The pelvic diaphragm constitutes the main for the pelvic viscera. 2) Piriformis muscle – this muscle is adjacent to the ischiococcygeus muscle, but is NOT part of the pelvic diaphragm 3) The Urogenital Diaphragm (UG diaphragm, aka deep pouch or deep space) The UG diaphragm fills a defect in the pelvic diaphragm. Fascia of the UG diaphragm is composed of two layers a. the superior fascia b. the inferior fascia, also know as the perineal membrane Note: Anything inferior to the inferior fascia is in the Superficial Pouch. Muscles of the UG Diaphragm are between these two fascial layers a. the sphincter urethra muscle b. the deep transverse perineal muscle Note: The urethra and vagina (in females) through the UG diaphragm. The rectum does NOT pierce the UG diaphragm. 4) The Superficial Space (Pouch) is composed of: a. Ischiocavernosus muscles (two) b. Bulbocavernosus muscles (or bulbospongiosus) (two) c. Superficial transverse perineal muscles (two) d. Branches of the pudendal nerve and vessels And in females only: e. Vestibular bulb- highly vascularized and extremely vulnerable to traumatic injury (straddle injury, for example) f. Bartholin gland a.k.a. Greater Vestibular Gland (two). Note: The superficial space is continuous with the anterior abdominal wall because the inferior fascia is continuous with Scarpa’s fascia. Practice Exam Question:

A four-year old girl fell on a fence, sustaining a “straddle” injury. A large hematoma is noted involving her perineum; within 12 hrs. her lower abdominal wall becomes “bluish” to the level of her umbilicus. Which of the following is true concerning the “superficial pouch”? 1. it contains the external iliac artery 2. it is continuous with Scarpa’s fascia of the anterior abdominal wall 3. it contains the sphincter urethrae muscle 4. it contains the femoral nerve (answer at end of COOP)

5) The deep pouch is enclosed by the superior and inferior fascias of the UG diaphragm. In males, the deep pouch contains: a) membranous urethra b) sphincter urethra c) bulbourethral gland’s (Cowper’s) d) deep transverse perineal muscle In females, the deep pouch contains: a) urethra b) sphincter urethral muscle c) inferior vagina d) deep transverse perineal muscle The Neural Pelvis [Netter 389-391 male, 393 female] 1) Obturator nerve (know the course of the nerve) * This nerve originates from L2-L4 and accompanies the obturator artery and vein. It runs along the superior pelvic aperture, crosses the sacroiliac t and es through the obturator canal, sending branches to the Obturator internus muscle and the Adductor muscles of the thigh. 2) Lumbosacral trunk * L4-L5, s up with S1-S3. 3) Sacral Plexus * Consists of: The lumbosacral trunk (L4-L5) and S1-S4. Includes the Pudendal n., Sciatic n., Superior Gluteal n., among others. 4) Sciatic nerve * L4-S3 * Will be discussed in greater detail in gluteal region. * es through the Greater Sciatic foramen. 5) Pudendal nerve (Know the course) [Netter 391, 393] * S2, 3, 4 * Exits at greater sacrosciatic foramen, re-enters the pelvis through the lesser sacrosciatic foramen, and travels through the pudendal canal. Visualized best in the gluteal region. * Branches include: 1. Inferior rectal n.—to the anal region 2. Deep perineal n. 3. Deep Branches to the urogenital diaphragm, which terminates as the Dorsal nerve of the penis/clitoris.

4. Posterior femoral cutaneous n. of the thigh and ilioinguinal region. Vast majority of innervation of perineum is from Pudendal Nerve. Vasculature of the Pelvis [Netter 378-385] The common iliac artery branches into Internal and External Iliac arteries. Branches of Internal Iliac artery [Netter 382-383]: 1. Anterior Division a) Umbilical artery * Gives rise to superior vesicular branches which supply the bladder; later obliterates and runs along the anterior abdominal wall as the umbilical ligament. b) Obturator A. * can come off the umbilical artery or directly off of the internal iliac artery. c) Internal Pudendal A. d) Inferior Gluteal A. e) Middle Rectal A. f) Uterine and vaginal artery 2. Posterior Division (just these 3, any others are part of the anterior division) a) Iliolumbar A. b) Lateral sacral A. c) Superior gluteal A. Know the relationship between the ureter and the uterine artery. The ureter es under the artery, as emphasized many times: “Water (ureter) runs under the bridge (uterine artery).” Blood supply of the ureter: abdominal—medial to lateral supply—renal branches pelvis – lateral to medial supply – internal iliac artery, then vesicular, uterine, vaginal branches. Dr. Bolender concluded the lecture with tips for the pelvis dissection. He said to follow c.12 in the dissection guide. 1. remove the skin to reveal the gluteus maximus 2. cut the gluteus maximus away from the sacrotuberous ligament, but don't cut the ligament. 3. the ischiorectal fossae is between the ischial tuberosity and the coccyx 4. the pudendal n.,a.,v. run together leaving the greater sacrosciatic foramen and entering the lesser sacrosciatic foramen.. 5. insert a tampon into the anus to give during the dissection. Answer to practice question: (2)