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Home , Retropubic space, Urogenital hiatus

MALE AND FEMALE PELVIC VISCERA AND PERITONEAL REFLECTIONS (Grants Dissector [16th Ed.] pp. 171-175 [Female] pp. 154-157 [Male reflections]

MALE AND FEMALE PELVIC VISCERA; PELVIC NEUROVASCULATURE (Grant's Dissector [16th Ed.] pp. 154-165 [Male]; 175-182 [Female]) ______TODAY’S GOALS: 1. Identify the peritoneal reflections in the male and female. 2. Identify the female internal genitalia and adnexa. 3. Identify the broad of the . 4. Identify the musculature of the lateral and posterior pelvic walls and the component muscles of the pelvic diaphragm. 5. Identify major branches of the internal iliac artery. 6. Identify the branches of the sacral plexus. 7. Identify internal features of male and female pelvic viscera. 8. Identify internal features and relationships of the anal canal.

MALE AND FEMALE PELVIC VISCERA AND PERITONEAL REFLECTIONS

DISSECTION NOTES: Male: Peritoneal Reflections (Fig. 5.15 and 5.17): reflects off the anterior onto the superior surface of the bladder (space of Retzius – ). It reflects along the sides of the bladder forming the paravesical fossae. At the posterior margin of the bladder, peritoneum reflects inferiorly and caps the superior aspect of the seminal vesicles. From here it lines the rectovesical fossae and is reflected onto the anterior surface of the middle part of the rectum and then along the sides of the rectum to form the pararectal fossae.

Female: Peritoneal reflections (Fig. 5.28 and 5.32): Peritoneum reflects off the anterior abdominal wall (space of Retzius – retropubic space) onto the superior surface of the bladder. It reflects along the sides of the bladder forming the paravesical fossae. At the posterior margin of the bladder, peritoneum reflects onto the anterior surface of the uterus where it forms the vesicouterine pouch (=anterior cul-de-sac). The peritoneum covers the uterus and fallopian tubes as the broad ligament of the uterus. From the posterior surface of the uterus, peritoneum extends over the posterior fornix of the and reflects onto the rectum forming the rectouterine pouch (=pouch of Douglas, posterior cul-de-sac). From here it reflects onto the anterior surface and sides of the rectum as the pararectal fossae. Note the sharp edge of the rectouterine folds. These contain the sacrouterine (sometimes difficult to see in the specimen) that anchor the uterus to the sacrum. These ligaments extend from the cervix of the uterus, around the sides of the rectum, to the sacrum. Extending from the lateral pelvic walls to the cervix is thickened fascia that forms the transverse cervical (Cardinal) ligaments. Less extensive pelvic fascia forms another pair of ligaments, the pubovesical ligaments, that connect the cervix (and pass on each side of the bladder) to the internal surface of the pubis. These ligaments provide important support for the female pelvic viscera. What is the primary support for the pelvic viscera?

The contains the bladder (apex recall the median umbilical fold) the uterus (Fig. 5.35, fundus and body) and the adnexa (adjacent parts):

• Uterine (fallopian) tubes – enter body of uterus near fundus. Identify the infundibular portion with its fimbriae. The isthmus represents its medial one-third. • – attached laterally to the ovarian vessels (suspensory ligament of the = Infundibular pelvic ligament – abbreviated IP ligament) and medially to the uterus via the round ligament of the ovary. • Round ligament of the uterus toward the (anatomical) deep inguinal ring.

The broad ligament of the uterus (Fig. 5.33 and 5.35) is formed by two layers of peritoneum draping over and thus covering adnexa. Parts of the broad ligament (Fig. 5.35): • - encloses the uterine (fallopian) tubes • - horizontal “shelf” of peritoneum at the posterior side of the broad ligament that connects to the ovary (but does not cover the ovary) • - remaining portion of broad ligament extending from the lateral surfaces of the body of the uterus

Contents of the broad ligament: (in addition to the above structures that are covered by the broad ligament) • Round ligament of the ovary - connects medial aspect of the ovary to lateral surface of uterus just below the entrance of the uterine (fallopian) tubes. • Suspensory ligament of the ovary (infundibular pelvic [IP] ligament) represents the fold of peritoneum that contains the ovarian vessels entering the lateral aspect of the ovary. • Round ligament of the uterus - continues from its attachment to the uterus and passes over the pelvic brim toward the anatomic deep inguinal ring (it corresponds to the ductus deferens in the male). What was this structure embryologically?

MALE AND FEMALE PELVIC VISCERA; PELVIC NEUROVASCULATURE

DISSECTION NOTES: General approach for both males and females Before the hemisection is performed, it is helpful to first tie off the rectum (double ligature, then divide between) deep within the true and mobilize it with its vascular supply out of the pelvis. On the right side of the pelvis, dissect and reflect away the peritoneum medially so that the following structures can be inspected.

Review. Bladder – apex (connected to urachus), body (area between apex and fundus), fundus (posterior surface; base of the bladder) – here the ureters enter its posterolateral surfaces, neck (location of internal urethral sphincter and orifice) Ureters – follow their course from the where they descend anterior to the external iliac vessels to enter the pelvis and posterior surface of the bladder Rectum Vessels – identify: Right common iliac a. + v. Right external iliac a. + v. Right internal iliac a. + v. Branches of the internal iliac arteries will be studied in greater detail following hemisection of the pelvis, as will the nerves.

Male Ductus (vas) deferens – follow its course from the deep inguinal ring inferiorly and medially to the posterolateral angle of the bladder where it crosses anterior to the ureter. Its diameter expands distally to form the ampulla Seminal vesicles – convoluted tubes located lateral to each ampulla Prostate – associated with the neck of the bladder and contains the prostatic

Female Uterus – Fundus, body Uterine tubes – enter body of uterus near fundus. Identify the infundibular portion with its fimbriae. The isthmus represents its medial one-third. Ovaries – attached laterally to the ovarian vessels and medially to the uterus via the round ligament of the ovary. Follow the round ligament of the uterus toward the deep inguinal ring.

Pelvic Musculature and Pelvic Diaphragm – common to male and female Reflection of the peritoneum should allow inspection of the musculature of the lateral wall of the pelvis, principally, the obturator internus muscle and the piriformis muscle. Identify the arcus tendineus (a band-like thickening of the obturator internus fascia) that extends from the ischial spine to the body of the pubic bone. Identify the pelvic diaphragm, which is the bowl-like muscular floor of the pelvic cavity. Its portion attaches along the arcus tendineus to the pubic bone; its coccygeus portion attaches from the ischial spine to the lower lateral surface of the sacrum and coccyx. The and anal hiatus are midline openings in the pelvic diaphragm that transmits the urethra and anal canal (in male) and urethra, vagina, and anal canal (in female).

Hemisection Instructions. Males (Dissector p. 156, Fig. 5.18 and P. 156, Fig. 5.19) Determine the midline of soft tissue structures that will be divided, i.e., penis, bladder, prostate, pelvic diaphragm, and rectum/anal canal. Using a sharp scalpel, divide these structures beginning at the symphysis pubis to the coccyx. Protect these structures during the saw cuts. With a hand saw, cut through the . Turn the body to the prone position and saw through the coccyx, sacrum, and lower lumbar vertebrae in the midline. Then turn the body on its left side and make a horizontal scalpel/saw cut through right lateral abdominal wall musculature and lumbar spine at the transiliac plane to intersect the midline saw cut, thereby mobilizing the right lower extremity. On one side, remove the peritoneum, fascia, and connective tissue, and prepare to view musculature and vessels. Similarly, on the opposite side, prepare it to view musculature and nerves.

Pelvic musculature (Dissector p. 164, Figs. 5.25). • Piriformis – arises from the anterolateral surfaces of the sacrum and exits the pelvis through the greater sciatic foramen before attaching to the greater trochanter of the femur. Ventral primary rami of S2 and S3 emerge from its anterior surface. • Obturator internus – arises from inner surface of obturator membrane and bony margin of this foramen. Its tendon exits the pelvis through the lesser sciatic foramen enroute to the greater trochanter of the femur. Note the arcus tendineus extending from the ischial spine to the body of the pubic bone. • Pelvic diaphragm – consists of the levator ani and coccygeus mm  Levator ani – 3 parts: . Puborectalis – most medial of the levator ani muscles and forms the margin of the urogenital hiatus. It attaches to the body of the pubic bone anteriorly and unites

with its member from the opposite side to form a “sling” around the distal end of the rectum . Pubococcygeus – located lateral to the puborectalis and attaches anteriorly to the pubic bone and to the anterior 1/3 of the tendinous arch. Posteriorly it attaches in the midline to the anococcygeal ligament and coccyx . Iliococcygeus – attaches anteriorly to the posterior 2/3’s of the tendinous arch and posteriorly to the anococcygeal ligament and coccyx  Coccygeus – attaches from the ischial spine to the inferior end of the sacrum/coccyx

Arteries (remove the veins to clarify the dissection field; they follow the arteries). (Dissector p. 161, Figs. 5.23) • External iliac • Internal iliac – 2 divisions:  Posterior division. . Iliolumbar . Lateral sacral . Superior gluteal (variably passes between L4 and L5 nerves or between L5 and S1 and leaves the pelvis through the greater sciatic nerve along the upper border of piriformis)  Anterior division. . Umbilical (including obliterated portion/medial umbilical ligament) artery – gives rise to:  Superior vesical aa – to superior surface of bladder . Obturator a – passes into the obturator canal. If missing, look for an aberrant or accessory obturator artery crossing the pelvic brim to the obturator canal. This artery is a branch from the external iliac or inferior epigastric arteries. . Inferior vesical – to bladder, seminal vesicle, and prostate . Middle rectal – follow to the rectum . Inferior gluteal (passes between S1 and S2 nerves and leaves pelvis via greater sciatic nerve along lower border of piriformis) . Internal pudendal (leaves pelvis along lower border of piriformis)

Nerves. – Remove all vasculature except for the stumps of arteries passing between nerves of the sacral plexus (Dissector p. 162, Figs. 5.24). Identify: • Obturator n. (L2,3,4) – passes to obturator canal • Lumbosacral trunk (L4,5) – descends on alae of sacrum and joins the sacral plexus • Sacral nn (S2-4) – ventral primary rami that emerge from the anterior sacral foramina • Pelvic splanchnics (preganglionic parasympathetic from S2,3,4) – slender branches that arise from sacral spinal nerves S2,3,4. They carry preganglionic parasympathetic fibers that will supply parasympathetic innervation to pelvic viscera and the GI tract distal to the left colic flexure. • Sciatic n. (L4-S3) – exits the pelvis by passing through the greater sciatic foramen, usually along the inferior border of piriformis • Pudendal n. (S2,3,4) – formed by contributions from S2,3,4 and leaves pelvis via the greater sciatic foramen along the lower border of piriformis • Inferior hypogastric plexus • Sympathetic trunk

Observe the Internal Surfaces of the Following Visceral Structures: • (Dissector p. 156, Figs. 5.19).  Detrusor musculature – lined by mucous membrane that is heavily folded when the bladder is empty  Trigone – an equilateral triangle on the posterior wall. The mucous membrane is smooth and tightly applied to the underlying musculature. The superior angles contain the openings of the right and left ureters and the inferior angle forms the internal urethral orifice.

• Prostate (Dissector p. 156, Figs. 5.19)  Prostatic urethra (~3 cm long). Its posterior wall contains a midline ridge = urethral crest  Seminal colliculus – an ovoid enlargement on the urethral crest. In its midline is a blind- ended opening called the prostatic utricle = homologue of the vagina  Ejaculatory ducts – formed by the union of the distal ends of the vas deferens and the seminal vesicles. These tiny ducts course through the prostate and open on each side of the utricle  Prostatic sinuses – grooves on each side of the urethral crest containing minute openings of multiple ducts of the prostate • Membranous urethra – short (~1 cm long). Passes through the UG diaphragm and is surrounded by the sphincter urethrae. • Spongy (penile) urethra – longest portion of urethra. Located within the corpus spongiosum of the penis Identify the deep dorsal vein of the penis and its communication with the prostatic venous plexus.

• Anal canal – located below the anorectal junction (Dissector p. 159, Figs. 5.22)  Anal columns – longitudinal ridges of mucous membrane containing anastomotic connections between the superior rectal veins (of the portal system) and the middle and inferior rectal veins (of the caval system)  Anal valves – semilunar folds that connect the distal ends of the anal columns. Behind each valve is a pocket-like space, called anal sinuses.  Pectinate line – an irregular line connecting the anal valves. This represents a “watershed” in terms of differences (above and below this line) in innervation, vascular supply, epithelial lining, and lymphatic drainage.  Pecten – a smooth area of stratified squamous epithelium. A transition area between distal end of rectum and skin around anus.  Internal anal sphincter – circular smooth muscle  External anal sphincter – composed of skeletal muscle

Hemisection Instructions. Females (Dissector pp. 172 - 173, Figs. 5.34) Determine the midline of soft tissue structures that will be divided, i.e., vulva, bladder, urethra, vagina, uterus, pelvic diaphragm, and rectum/anal canal. Using a sharp scalpel, divide these structures beginning at the symphysis pubis to the coccyx. Protect these structures during the saw cuts. With a hand saw, cut through the pubic symphysis. Turn the body to the prone position and saw through the coccyx, sacrum, and lower lumbar vertebrae in the midline. Then turn the body on its left side and make a horizontal scalpel/saw cut through right lateral abdominal wall musculature and lumbar spine at the transiliac plane to intersect the midline saw cut, thereby mobilizing the right lower extremity. On one side, remove the peritoneum, fascia, and connective tissue, and prepare to view musculature and vessels. Similarly, on the opposite side, prepare it to view musculature and nerves.

Pelvic musculature (Dissector p. 181, Figs. 5.41). • Piriformis – arises from the anterolateral surfaces of the sacrum and exits the pelvis through the greater sciatic foramen before attaching to the greater trochanter of the femur. Ventral primary rami of S2 and S3 emerge from its anterior surface. • Obturator internus – arises from inner surface of obturator membrane and bony margin of this foramen. Its tendon exits the pelvis through the lesser sciatic foramen enroute to the greater trochanter of the femur. Note the arcus tendineus extending from the ischial spine to the body of the pubic bone. • Pelvic diaphragm – consists of the levator ani and coccygeus mm  Levator ani – 3 parts: . Puborectalis – most medial of the levator ani muscles and forms the margin of the urogenital hiatus. It attaches to the body of the pubic bone anteriorly and unites with its member from the opposite side to form a “sling” around the distal end of the rectum . Pubococcygeus – located lateral to the puborectalis and attaches anteriorly to the pubic bone and to the anterior 1/3 of the tendinous arch. Posteriorly it attaches in the midline to the anococcygeal ligament and coccyx . Iliococcygeus – attaches anteriorly to the posterior 2/3’s of the tendinous arch and posteriorly to the anococcygeal ligament and coccyx  Coccygeus – attaches from the ischial spine to the inferior end of the sacrum/coccyx

Arteries (remove the veins to clarify the dissection field; they follow the arteries). (Dissector p. 178, Figs. 5.39) • External iliac • Internal iliac – 2 divisions:  Posterior division. . Iliolumbar . Lateral sacral . Superior gluteal (variably passes between L4 and L5 nerves or between L5 and S1 and leaves the pelvis through the greater sciatic nerve along the upper border of piriformis)  Anterior division. . Umbilical (including obliterated portion/medial umbilical ligament) artery – gives rise to:  Superior vesical aa – to superior surface of bladder . Obturator a – passes into the obturator canal. If missing, look for an aberrant or accessory obturator artery crossing the pelvic brim to the obturator canal. This artery is a branch from the external iliac or inferior epigastric arteries.

. Uterine a – courses medially within endopelvic fascia at the inferior attachment of the broad ligament to the lateral border of the uterus. It crosses over the ureter (“water” [=urine] under the “bridge” [=uterine a.]) . Vaginal a – either a branch of the uterine or a separate branch off the internal iliac. The ureter is interposed between the vaginal and uterine arteries during its descent to the bladder. . Middle rectal – follow to the rectum . Inferior gluteal – passes between S1 and S2 nerves and leaves pelvis via greater sciatic nerve along lower border of piriformis . Internal pudendal – leaves pelvis along lower border of piriformis

Nerves. – Remove all vasculature except for the stumps of arteries passing between nerves of the sacral plexus. (Dissector p. 180, Figs. 5.40). Identify: • Obturator n. (L2,3,4) – passes to obturator canal • Lumbosacral trunk (L4,5) – descends on alae of sacrum and joins the sacral plexus • Sacral nn (S2-4) – ventral primary rami that emerge from the anterior sacral foramina • Pelvic splanchnics (preganglionic parasympathetic from S2,3,4) – slender branches that arise from sacral spinal nerves S2,3,4. They carry preganglionic parasympathetic fibers that will supply parasympathetic innervation to pelvic viscera and the GI tract distal to the left colic flexure. • Sciatic n. (L4-S3) – exits the pelvis by passing through the greater sciatic foramen, usually along the inferior border of piriformis • Pudendal n. (S2,3,4) – formed by contributions from S2,3,4 and leaves pelvis via the greater sciatic foramen along the lower border of piriformis • Inferior hypogastric plexus • Sympathetic trunk

Observe the Internal Surfaces of the Following Visceral Structures: • Urinary Bladder (Dissector p. 176, Figs. 5.37).  Detrusor musculature – lined by mucous membrane that is heavily folded when the bladder is empty  Trigone – an equilateral triangle on the posterior wall. The mucous membrane is smooth and tightly applied to the underlying musculature. The superior angles contain the openings of the right and left ureters and the inferior angle forms the internal urethral orifice. • Urethra – short (~3-4 cm in length). Follow it through the UG diaphragm to the external urethral orifice. Note that the urethra lies anterior to the vagina. • Uterus  Uterine cavity of body of uterus – endometrium and myometrium  Cervical canal (of cervix) – internal and external ostia  Vagina – observe its anterior, lateral, and posterior fornices. Observe that its anterior wall is shorter than its posterior wall.

• Anal canal – located below the anorectal junction (Dissector p. 177, Figs. 5.38)  Anal columns – longitudinal ridges of mucous membrane containing anastomotic connections between the superior rectal veins (of the portal system) and the middle and inferior rectal veins (of the caval system)

 Anal valves – semilunar folds that connect the distal ends of the anal columns. Behind each valve is a pocket-like space, called anal sinuses.  Pectinate line – an irregular line connecting the anal valves. This represents a “watershed” in terms of differences (above and below this line) in innervation, vascular supply, epithelial lining, and lymphatic drainage.  Pecten – a smooth area of stratified squamous epithelium. A transition area between distal end of rectum and skin around anus.  Internal anal sphincter – circular smooth muscle  External anal sphincter – composed of skeletal muscle

PEER TEACHING GUIDE: Organize your narrative to minimally include: 1. Demonstration of the peritoneal reflections in male and females. 2. Demonstration of the female internal genitalia. 3. Demonstration of the broad ligament and contents. 4. Demonstration of the musculature of the lateral and posterior pelvic walls and the muscular components of the pelvic diaphragm. 5. Demonstration of the major branches of the internal iliac arteries and their distribution. 6. Demonstration of the branches of the sacral plexus and their distribution. 7. Demonstration of the internal features of male and female pelvic viscera. 8. Demonstration of the internal features of the anal canal.