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The Structural Basis of Medical Practice (SBMP) - Human Gross Anatomy, Radiology, and Embryology

Answer Guide for Abdomen, Pelvis, and Perineum: Written Examination Part V (50 pts) - September 27, 1997

The College of Medicine at The Pennsylvania State University


Note: This is an outline of items to discuss -- NOT the "Answer"

Part V. Answer in the space provided. (50 pts)

  1. A 45-year old woman who has had 4 children and 2 miscarriages presents with a prolapse of the uterus. Indicate your understanding of the following with respect to the uterus, uterine tubes, and ovary: Structure, orentation, relationships (anterior, posterior, superior, inferior, medial, lateral), support(s) and peritoneal associations, innervation (sensory and motor), vasculature and lymphatics, and briefly discuss the anatomical explanation for prolapse of the uterus. (15 pts)
    1. Uterus
      1. Structure
        1. Pear shaped hollow organ - 8cm long, 5cm wide
        2. myometrium and endometrium
        3. cervix, body, fundus
        4. external os, cerivical canal, internal os, uterine cavity
      2. Orientation
        1. anteflexed and anteverted (lengthens posterior fornix vagina)
      3. Support
        1. Broad lig. - visceral lig (peritoneum)
          1. lateral uterus to parietal peritoneum of lateral pelvic wall
        2. fibrous ligs derived from endopelvic fascia
          1. utereosacral, pubouteral, and lateral cervical (Cardinal) ligs.
        3. round lig to lateral anterior pelvic brim - anterior lamina broad lig.
        4. ovarian lig to posterior abdominal wall via suspensory lig. ovary
      4. Relations
        1. anterior: bladder, vesicouterine pouch
        2. posterior: rectum, rectouterine pouch
        3. superior: false pelvis, abdominal cavity
        4. inferior: vagina, posterior fornix, rectouterine pouch
        5. lateral: broad lig, pelvic wall, ovary, uterine tube
      5. vasculature and lymphatics,
        1. uterine a. at the cervix and ovarian a. at the fundus
          1. ovarian v. to ivc on right and left renal v. on left
          2. uterine venous complex into internal iliac vv.
        2. fundus drains lymph to upper lumbar nodes along ovarian vessels
        3. superior body near round ligament drains lymph to superficial inguinal nodes
        4. cervix drains lymph toward internal iliac nodes
      6. innervation
        1. sympathetic by way of inferior hypogastric plexus to uterovaginal plexus along uterine a.
          1. preganglionic in IMLCC lower thoracic and upper lumbar
          2. postganglionic in microscopic ganglia of aortic and hypogastric plexuses
        2. parasympathetic: unknown if present
        3. sensory pain follow sympathetic pathways (eg. hypogastric nerves)
    2. Uterine Tube
      1. Structure
        1. shaped as a salpinx and about 10 cm long
        2. connects uterine cavity to the peritoneal cavity
        3. isthmus, ampulla, infundibulum, fimbriae
      2. Orientation
        1. courses laterally from fundus of uterus toward pelvic wall
        2. intraperitoneal in superior free edge of broad lig.
        3. cradles ovary as a posterior relation
      3. Support
        1. mesosalpinx - visceral lig (peritoneum) part of broad lig.
          1. continuous with mesovarium
        2. ovarian lig to posterior abdominal wall via suspensory lig. ovary
      4. Relations
        1. anterior: bladder, vesicouterine pouch
        2. posterior: broad lig., rectum, rectouterine pouch, ovary
        3. superior: false pelvis, abdominal cavity
        4. inferior: broad lig., rectouterine pouch
        5. lateral: broad lig, pelvic wall, ovary, ovarian fossa, uterine tube
        6. medial: fundus and body of uterus
      5. vasculature and lymphatics,
        1. tubal a., uterine a. at the cervix and ovarian a. at the fundus
          1. uterine venous complex to internal iliac vv
        2. drains lymph to upper lumbar nodes along ovarian vessels
        3. drains lymph to superficial inguinal nodes
        4. drains lymph toward internal iliac nodes
      6. innervation
        1. sympathetic by way of inferior hypogastric plexus to uterovaginal plexus along uterine a.
          1. preganglionic in IMLCC lower thoracic and upper lumbar
          2. postganglionic in microscopic ganglia of aortic and hypogastric plexuses
        2. sympathetic by way of ovarian plexus
        3. parasympathetic: unknown if present
        4. sensory pain follow sympathetic pathways
    3. Ovary
      1. structure and support
        1. The ovary is roughly cylindrical about 3 cm long and 1 cm in diameter. The visceral peritoneum covering the ovary gives way to a specialized germinal epithelial cell layer. The egg is able to penetrate this layer and enter the peritoneal cavity.
        2. The ovary is suspended from the posterior lamina of the broad ligament by the mesovarium -- a peritoneal ligament. Supporting the superior pole of the ovary to the pelvic brim is the suspensory ligament of the ovary. Supporting the inferior pole of the ovary to the lateral uterus is the ovarian ligament.
      2. relationships
        1. superior to the ovary is the pelvic brim and suspensory ligament
        2. inferior to the ovary is the uterine wall and the ovarian ligament
        3. anterior to the ovary is the broad ligament, uterine tube, and fimbria of uterine tube
        4. posterior to the ovary is the rectum and pelvic floor
        5. medial to the ovary is the pararectal fossa, rectouterine pouch, fundus of the uterus
        6. lateral to the ovary is the ovarian fossa (internal iliac a. and ureter), psoas major muscle, and obturator n.
      3. innervation (motor and sensory)
        1. Parasympathetic preganglionic cell bodies are located in the central gray of the spinal cord (IMLCC) at levels S2-4. Preganglionic fibers enter the inferior hypogastric plexus by way of the pelvic splanchnic nerves. The inferior hypogastric plexus contributes a uterine plexus and then to the ovarian plexus. Postganglionic parasympathetic cell bodies are located in intrinsic ganglia of the ovary. The above pathway assumes that the uterovaginal plexus reaches the ovary. This is not known for certain. Parasympathetic pregangionic contributions from the vagus n. may also follow the ovarian plexus.
        2. Sympathetic preganglionic cell bodies are located in the interomedial lateral cell column at cord levels T10 (and perhaps T11-12). Preganglionic fibers follow the lesser and least splanchnic nerves to aortic ganglia near (and including) the superior mesenteric ganglion and the aorticorenal ganglion. Postganglionic fibers from these ganglia enter the aortic plexus and extend along the ovarian artery as the ovarian plexus. Visceral afferent pathways follow the sympathetic pathways up to the T10 spinal level. Additional visceral pathways follow parasympathetic pathways back to the S3-4 spinal levels.
      4. blood supply and lymphatics
        1. The arterial supply is mostly from the ovarian arteries. These are paired arteries arising from the anterolateral surface of the aorta near the level of the third lumbar vertebra. The ovarian veins arise from the IVC on the right and the left renal vein on the left. Additional blood supply is by ascending branches of the uterine vessels (ovarian br.) that anastomose with the ovarian vascular supply. Lymph drainage is primarily along the embryological decent of the ovary. This includes upper lumbar nodes in the vicinity of the renal arteries. Much of the vascular supply reaches the ovary through the suspensory ligament.
    4. Prolaps of Uterus
      1. Weakening of the ligamentus support of the uterus leads to prolapse
        1. most noteably, the lateral cervical ligs and important
  2. Dysfunction of the duodenum because of intrinsic failure and/or impairment due to associated structures is crucial to comprehending gastrointestinal disorders. Discuss the parts of the duodenum with respect to the following: Structure, relationship to surrounding structures, innervation (sensory and motor), vasculature, lymphatics, supports (visceral and fibrous), and indicate briefly a clnical significance for each part of the duodenum (15 pts)
    1. Part 1
      1. Relationships and boundaries
        1. Vertebral level L1
        2. Posterior
          1. inferior vena cava
          2. pancreas, bile duct, gastroduodenal a.
        3. Anterior
          1. liver and gall bladder
        4. Superior
          1. margin of epiploic foramen
        5. Inferior
          1. transverse mesocolon and right colic flexure
        6. Medial
          1. pancreas, stomach, lessor omentum
        7. Lateral
          1. second part of duodenum and gall bladder
      2. Contents and Special Features
        1. Forms the duodenal cap
        2. no plicae circulares
          1. smooth walled
        3. recieves stomach contents directly via pylorus
          1. high acidity may cause ulceration
        4. partly intraperitoneal
          1. attachment of hepatoduodenal ligament (lessor omentum)
          2. attachment of greater omentum
      3. Vascular Supply
        1. gastroduodenal artery
          1. superior part by supraduodenal
          2. inferior part by retroduodenal
          3. superior anterior and posterior pancreaticoduodenal arteries
        2. Veins follow similar pathways peripherally but drain into portal vein centrally.
      4. Innervation
        1. Parasympathetic
          1. preganglionics derived from vagus nerve and travel in celiac mesenteric plexuses.
          2. postganglionics located in intrinsic ganglia of the duodenum
        2. Sympathetic
          1. preganglionics (IMLCC T5-T9) travel in greater splanchnic nerve
          2. pierce cura of diaphragm and enter celiac ganglia on sides of aorta near celiac arterial trunk
          3. postganglionics derived from cell bodies located in celiac ganglia
            1. travel to duodenum along arterial extensions of the celiac mesenteric plexuses
      5. Lymphatic drainage
        1. primary drainage into pyloric nodes and right gastroepiploic nodes
        2. celiac nodes to intestinal lymph trunk and to cysterna chyli
      6. Suport
        1. pylorus and hepatoduodenal ligament
    2. Part II
      1. Relationships and boundaries
        1. Vertebral level L1-L3
        2. Posterior - hilum of right kidney
        3. Anterior - attachment of transverse mesocolon
        4. Superior - liver
        5. Inferior - jejunum
        6. Medial - pancreas and common bile duct
        7. Lateral = right colic flexure
      2. Contents and Special Features (3 pts)
        1. Beginning of plicae circulares
        2. Minor duodenal papilla - accessory pancreatic duct
        3. Major duodenal papilla - chief pancreatic duct
          1. Sphincter of Oddi
          2. Ampulla of Vater
      3. Vasculature and lymphatic supply
        1. Superiorly from gastroduodenal artery
          1. superior anterior and posterior pancreaticoduodenal arteries
        2. Inferiorly from superior mesenteric artery
          1. inferior anterior and posterior pancreaticoduodenal arteries
        3. Veins follow similar pathways peripherally but drain into portal vein centrally.
        4. Lymphatic drainage
          1. primary drainage into pyloric nodes and right gastroepiploic nodes
          2. celiac nodes to intestinal lymph trunk and to cysterna chyli
      4. Innervation
        1. Parasympathetic
          1. preganglionics derived from vagus nerve and travel in celiac and superior mesenteric plexuses.
          2. postganglionics located in intrinsic ganglia of the duodenum
        2. Sympathetic
          1. preganglionics from greater splanchnic (T5-T9) and lesser splanchnic (T10-T11) nerves
            1. travel to celiac and superior mesenteric ganglia respectively
          2. postganglionics from celiac and superior mesenteric ganglia
            1. travel to duodenum along arterial extensions of the celiac and superior mesenteric plexuses
      5. Support
        1. retroperitoneal - extraperitoneal connective tissue
        2. head of pancreas and common bile duct
    3. Part III
      1. Structure and relations,
        1. These superior mesenteric artery branches from the aorta near the L2 vertebral level. It courses inferiorly and anterior resulting in the formation of a "V" by the superior mesenteric artery and the aorta.
        2. Crossing the aorta just inferior to the branching of the superior artery is the left renal vein. The horizontal portion of the duodenum crosses the aorta immediately inferior to the left renal vein at the L3 level.
        3. A swelling of the superior mesenteric artery near its origin from the aorta or a swelling of the aorta just distal to the origin of the superior mesenteric artery could compress the left renal vein and the duodenum.
        4. Vomiting and left kidney problems could result.
      2. Innervation (similar to part II with a bias toward superior mesenteric plexus)
        1. Sympathetic
          1. Preganglionic cell bodies - IMLCC of T10-11
            1. fibers travel within lesser splanchnic n.
          2. Postganglionic cell bodies - Supererior mesenteric ganglion
            1. fibers travel with extensions of superior mesenteric plexus along inferior anterior/posterior pancreaticoduodenal aa.
        2. Parasympathetic
          1. preganglionic cell bodies in dorsal motor nucleus of vagus nerve
            1. preganglionic fibers travel through super mesenteric ganglion without synapsing and contribute to superior mesenteric plexus
        3. General visceral afferent fibers follow sympathetic (pain) and vagal (visceral reflexes) pathways.
      3. Vasculature and lymphatic supply
        1. inferior anterior/posterior pancreaticoduodenal aa and vv
          1. aa. from superior mesenteric a. from aorta
          2. vv. from superior mesenteric v. from portal v.
        2. lymphatic drainage to superior mesenteric nodes to intestinal trunk to lumbar trunk to cysterna chyli
      4. Support
        1. retroperitoneal - extraperitoneal connective tissue
      5. Clinical significance
        1. A swelling of the superior mesenteric artery near its origin from the aorta or a swelling of the aorta just distal to the origin of the superior mesenteric artery could compress the left renal vein and the duodenum.
        2. Vomiting and left kidney problems could result.
    4. Part IV
      1. Structure and relations
        1. The 4th part of the duodenum is located at the level of the second lumbar vertebra and crosses the anterior surface of the aorta. It is the last part of the duodenum and ends at the duodenojejunal junction where the suspensory ligament of Treitz marks the end of the retroperitoneal course of the duodenum and the beginning of the intestinal mesentary. Crossing anteriorly is the transverse mesocolon and gastrocolic ligament and stomach. Superiorly is the body of the pancreas. posteriorly and to the left is the hilum of the left kidney. Paraduodenal recesses are somtimes present. These recesses can entrap viscera.
      2. Innervation
        1. The autonomic nerve supply is from the superior mesenteric plexus. Preganglionic sympathetic fibers within the lesser splanchnic nerve are derived from cell bodies in the interomediolateral cell columns of spinal cord levels T10 and T11. Postganglionic fibers arise from cell bodies in the superior mesenteric ganglion. These fibers help form the superior mesenteric plexus. Parasympathetic preganglionic fibers travel with branches of the vagus nerve to enter into the superior mesenteric plexus. The parasympathetic postganglionic cell bodies are located in enteric ganglia within the wall of the duodenum.
        2. General visceral afferent fibers follow sympathetic (pain) and vagal (visceral reflexes) pathways
        3. Sympathetic
          1. Preganglionic cell bodies - IMLCC of T10-11
            1. fibers travel within lesser splanchnic n.
          2. Postganglionic cell bodies - Supererior mesenteric ganglion
            1. fibers travel with extensions of superior mesenteric plexus along inferior anterior/posterior pancreaticoduodenal aa.
        4. Parasympathetic
          1. preganglionic cell bodies in dorsal motor nucleus of vagus nerve
            1. preganglionic fibers travel through super mesenteric ganglion without synapsing and contribute to superior mesenteric plexus
            2. postganglionic cell bodies in enteric ganglia
      3. Vasculature and lymphatic supply
        1. The chief arterial supply is from the inferior anterior and posterior pancreaticoduodenal arteries arising from the trunk of the superior mesenteric artery. Additional supply may come from the first jejunal artery. The venous drainage follows the same named arteries and empty into the portal vein by way of the superior mesenteric vein.
        2. The primary lymph drainage is into superior mesenteric and upper lumbar nodes and the intestinal lymph trunks into the cysterna chyli.
      4. Support
        1. ligament of Treitz
  3. A tear in the membranous urethra and superior fascia during catheterization allows urine to extravasate into the ischiorectal fossa. Discuss the boundaries and contents of the ischiorectal fossa. What is the relationship of the ischiorectal fossa to the deep and superficial pouches? Given this medical situation, would ruine be expected to enter the deep and/or superficial pouches? (12 pts)
    1. Define the boundaries and contents of the ischiorectal fossa
      1. Boundaries of the ischiorectal fossa
        1. Anterior (above UG diaphragm): The anterior superior recess of the ischiorectal fossa
        2. Anterior (below UG diaphragm): Superficial perineal fascia (Scarpa's f.)
        3. Posterior: Gluteus Maximus
        4. Superior: Inferior fascia of the pelvic diaphragm
        5. Inferior: Skin of anal triangle
        6. medial: Rectum and perineal body
      2. Contents of the ischiorectal fossa
        1. loose areolar fat
        2. pudendal canal
        3. inferior rectal nerves and vessels
        4. arteries and nerves to the penis or clitoris
    2. Explain why urine can easily pass between the anterior and posterior recesses. (Define these recesses).
      1. The superior anterior recess is a part of, and thus, continuos with, the ischiorectal fossa. Urine can travel freely throughout the fossa.
      2. Boundaries of the superior anterior recess.
        1. Superior: Inferior fascia of the pelvic diaphragm
        2. Inferior: Superior fascia of the UG diaphragm
        3. Lateral: Conjoint ramus and obturator internus
        4. Medial: Fusion of inferior fascia of the pelvic diaphragm to the superior fascia of the UG diaphragm.
          1. Pelvic viscera are palpable: prostate in male and neck of bladder in female.
    3. Discuss why urine cannot pass into the superficial pouch.
      1. Urine does not pass from the ischiorectal fossa into the superficial pouch because Scarpa's fascia attaches to the posterior free edge of the UG diaphragm and contributes part of the anterior boarder of the ischiorectal fossa.
      2. The inferior fascia of the UG diaphragm is intact and prevents urine from leaking inferiorly from the deep pouch into the superficial pouch.
    4. Discuss why urine is located in the deep pouch.
      1. The deep pouch is between the superior and inferior fascia of the UG diaphragm. Extravasation of urine resulted from tearing the superior fascia of the UG diaphragm. This indicates that the membranous urethra is torn. Urine is leaking into the deep pouch and then through the superior fascia into the anterior recess of the ischiorectal fossa.
  4. Discuss the course and branches of the pudendal nerve. (8 pts.)
    1. derived from sacral plexus (S2-4)
    2. leaves pelvic via greater sciatic foramen to enter gluteal region
    3. loops posterior to ischial spine to enter ischiorectal fossa via lesser sciatic foramen
    4. enters pudendal canal
      1. osseofibrous canal formed by obturator internus fascia and falciform edge of ischial tuberosity
      2. elaborates inferior rectal branch just before canal or from within canal
        1. courses inferior, medial, and anterior through fatty tissue toward anorectal area
      3. exits canal at posterior free edge of urogenital diaphragm within ischiorectal fossa
    5. elaborates terminal branches
      1. superficial perineal n. - posterior scrotal (labial)
      2. deep perineal n. - pierces superficial perineal fascia to enter superficial pouch
        1. to muscles of superficial and deep pouches
      3. dorsal n. of the clitoris or penis
        1. runs along conjoint ramus within anterior recess ischiorectal fossa.
        2. pierces tranverse perineal ligament to enter onto dorsum of penis or clitoris
          1. resides lateral to deep dorsal vein and dorsal artery
        3. other descriptions indicate a course through the superficial and deep pouches
          1. both descriptions are verified on dissection

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