Human Gross Anatomy - Answer Guide for Pelvis, Abdomen, and Perineum Essay Examination (36 pts)
September 05, 2003
(The following is a guide to answering the questions and is not the "answer.")
[ SBMP ] [ Lab Key ] [ Short Ans Key ]
[ Essay Guide ] [ Lab Results ] [ Written Results ]
[ Cumulative Results ]
[Transverse Colon ] [ Uterus, Uterine Tube, and Ovary ]
[ Boundaries of Scarpa's fascia ]
Discuss the anatomy of the transverse colon. Include structure, support, relationships, innervation, vasculature, and lymphatics. (12 pts)
- General comments: The transverse colin is an intraperitoneal segment of the large bowel. It spans from the right colic flexure to the left colic flexure.
Surgical access to the lesser sac is provided by the gastrocolic ligament. The transverse colon divides the greater sac into supracolic and infracolic compartments.
- Structure -
- Layers - from inner to outer
- mucosa (columnar epitheleum) - no villi in large intestine
- submucosa (vascular and submucosal nerve plexuses) - padding between mucosa and muscular layer
- tunica muscularis - inner circular and outer longitudinal smooth muscle, myenteric plexus, peristalsis
- mesothelium and connective tissue
- serosa - visceral peritoneum covers the transverse colon except at the attachment of transverse mesocolon
- teniae coli - 3 longitudinal bands of smooth muscle
- haustra coli - sacculations caused by the teniae coli being shorter than the gut tube
- appendices epiploicae - fat appendages hanging from the teniae
- caliber is generally larger than the small intestine
- support -
- Right
- superior aspect of retroperitoneal ascending colon, cradled by right lobe of liver
- right hepatocolic ligament
- Middle
- transverse mesocolon attaches to posterior abdominal wall crossing right kidney, duodenum, IVC, aorta, pancreas, left kidney
- gastrocolic ligament provides anchoring to the stomach
- Left
- relationships -
- Right - level of L2
- Superior - liver, gallbladder, descending duodenum
- Inferior - coils of jejunum and ileum
- Anterior - costal margin, diaphragm, liver
- Posterior - diaphragm, right kidney, inferior vena cava, pancreas, quadratus lumborum
- Lateral left -
- Lateral right - liver, right paracolic gutter, hepatorenal recess
- Middle - level of L1-2
- Superior - stomach, gastrocolic ligament, liver, lesser sac
- Inferior - coils of jejunum and ileum
- Anterior - greater omentum, costal margin, diaphragm, falciform ligament
- Posterior - pancreas (head, body, and tail), horizontal duodenum, aorta, superior mesenteric artery, intestinal mesentery
- Lateral left - left colic flexure (see below)
- Lateral right -right colic flexure (see above)
- Left - level of T12-L1
- Superior - spleen, diaphragm
- Inferior - jejunum, descending colon, left paracolic gutter
- Anterior - diaphragm
- Posterior - diaphragm, left kidney, quadratus lumborum
- Lateral left - phrenicocolic ligament, superior aspect of left paracolic gutter
- Lateral right -
- innervation -
- Right Side
- Parasympathetic
- Preganglionic
- vagus nerves
- preganglionic pathway - vagus nerves, superior mesenteric ganglion (no synapse), superior mesenteric plexus, right and middle colic arteries
- Postganglionic
- enteric ganglia at the target
- cell bodies in submucosal layer - postganglionic fibers contribute to submucous plexus, enteric plexus
- Sympathetic
- Preganglionic
- cell bodies within intermediolateral cell column (IMLCC) of T10-11
- preganglion fiber path - ventral root to spinal nerve, to ventral ramus, white ramus communican, thoracic sympathetic trunk, thoracic splanchnic nerves, lesser splanchnic nerve
- Postganglionic
- cell bodies in the superior mesenteric ganglion
- postganglionic fiber pathway - superior mesenteric plexus, right colic artery, middle colic artery, enteric plexus
- Visceral Afferent
- High threshold (pain)
- follow sympathetic preganglionic and sympathetic postganglionic pathways
- Low threshold (homeostatic)
- Left Side
- Parasympathetic
- Preganglionic
- pelvic splanchnics
- preganglionic pathway - IMLCC S2-4, pelvic splanchnics, inferior hypogastric plexus, left hypogastric nerve, sigmoid mesocolon, retroperitoneal along medial margin of descending colon, left transverse mesocolon
- Postganglionic
- enteric ganglia at the target
- cell bodies in submucosal layer - postganglionic fibers contribute to submucous plexus, enteric plexus
- Sympathetic
- Preganglionic
- cell bodies within intermediolateral cell column (IMLCC) of L1-3
- preganglion fiber path - ventral root to spinal nerve, to ventral ramus, white ramus communican, lumbar sympathetic trunk, lumbar splanchnic nerves, aoric plexus, inferior mesenteric ganglia (synapse here)
- Postganglionic
- cell bodies in the inferior mesenteric ganglia
- postganglionic fiber pathway - inferior mesenteric plexus, left colic artery, enteric plexus
- Visceral Afferent
- High threshold (pain)
- follow sympathetic preganglionic and sympathetic postganglionic pathways
- Low threshold (homeostatic)
- follow parasympathetic preganglionic pathway (see parasympathetic preganglionic pathway)
- vasculature - provided by the arteriovenous supply of midgut and hindgut, venous drainage is into portal system
- Right
- right colic artery/vein from superior mesenteric artery/vein
- retroperitoneal up to right colic flexure
- contributes to marginal artery/vein
- Middle
- middle colic artery/vein from superior mesenteric artery/vein
- travels through to transverse mesocolon
- contributes to marginal artery/vein
- Left
- left colic artery/vein from inferior mesenteric artery/vein
- retroperitoneal up to left colic flexure
- contributes to marginal artery/vein
- lymphatics - intestinal nodes to central nodes (superior and inferior mesenteric nodes) to intestinal lymph trunks to cysterna chyli
- Right
- paracolic nodes to superior mesenteric nodes
- Middle
- paracolic nodes to superior mesenteric nodes
- Left
- paracolic nodes to inferior mesenteric nodes
Provide a comprehensive review of the uterus, uterine tubes, and ovary. Include structure, support, relationships, vasculature, innervation,
lymphatic drainage, and function. (12 pts)
- Uterus
- Structure
- Pear shaped hollow organ - 8cm long, 5cm wide
- myometrium and endometrium
- cervix, body, fundus
- external os, cerivical canal, internal os, uterine cavity
- Orientation
- anteflexed and anteverted (lengthens posterior fornix vagina)
- Support
- intraperitoneal organ
- Broad lig. - visceral lig (peritoneum)
- lateral uterus to parietal peritoneum of lateral pelvic wall
- fibrous ligs derived from endopelvic fascia
- utereosacral, pubouteral, and lateral cervical (Cardinal) ligs.
- round lig to lateral anterior pelvic brim - anterior lamina broad lig.
- ovarian lig to posterior abdominal wall via suspensory lig. ovary
- Relations
- anterior: bladder, vesicouterine pouch
- posterior: rectum, rectouterine pouch
- superior: false pelvis, abdominal cavity
- inferior: vagina, posterior fornix, rectouterine pouch
- lateral: broad lig, pelvic wall, ovary, uterine tube
- vasculature and lymphatics,
- uterine a. at the cervix and ovarian a. at the fundus
- ovarian v. to ivc on right and left renal v. on left
- uterine venous complex into internal iliac vv.
- fundus drains lymph to upper lumbar nodes along ovarian vessels
- superior body near round ligament drains lymph to superficial inguinal nodes
- cervix drains lymph toward internal iliac nodes
- innervation
- sympathetic by way of inferior hypogastric plexus to uterovaginal plexus along uterine a.
- preganglionic in IMLCC lower thoracic and upper lumbar
- postganglionic in microscopic ganglia of aortic and hypogastric plexuses
- parasympathetic: unknown if present
- sensory pain follow sympathetic pathways (eg. hypogastric nerves)
- Uterine Tube
- Structure
- shaped as a salpinx and about 10 cm long
- connects uterine cavity to the peritoneal cavity
- isthmus, ampulla, infundibulum, fimbriae
- Orientation
- courses laterally from fundus of uterus toward pelvic wall
- intraperitoneal in superior free edge of broad lig.
- cradles ovary as a posterior relation
- Support
- mesosalpinx - visceral lig (peritoneum) part of broad lig.
- continuous with mesovarium
- ovarian lig to posterior abdominal wall via suspensory lig. ovary
- Relations
- anterior: bladder, vesicouterine pouch
- posterior: broad lig., rectum, rectouterine pouch, ovary
- superior: false pelvis, abdominal cavity
- inferior: broad lig., rectouterine pouch
- lateral: broad lig, pelvic wall, ovary, ovarian fossa, uterine tube
- medial: fundus and body of uterus
- vasculature and lymphatics,
- tubal a., uterine a. at the cervix and ovarian a. at the fundus
- uterine venous complex to internal iliac vv
- drains lymph to upper lumbar nodes along ovarian vessels
- drains lymph to superficial inguinal nodes
- drains lymph toward internal iliac nodes
- innervation
- sympathetic by way of inferior hypogastric plexus to uterovaginal plexus along uterine a.
- preganglionic in IMLCC lower thoracic and upper lumbar
- postganglionic in microscopic ganglia of aortic and hypogastric plexuses
- sympathetic by way of ovarian plexus
- parasympathetic: unknown if present
- sensory pain follow sympathetic pathways
- Ovary
- structure and support
- 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.
- 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.
- relationships
- superior to the ovary is the pelvic brim and suspensory ligament
- inferior to the ovary is the uterine wall and the ovarian ligament
- anterior to the ovary is the broad ligament, uterine tube, and fimbria of uterine tube
- posterior to the ovary is the rectum and pelvic floor
- medial to the ovary is the pararectal fossa, rectouterine pouch, fundus of the uterus
- lateral to the ovary is the ovarian fossa (internal iliac a. and ureter), psoas major muscle, and obturator n.
- innervation (motor and sensory)
- 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.
- 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.
- blood supply and lymphatics
- 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.
- Prolaps of Uterus
- Weakening of the ligamentus support of the uterus leads to prolapse
- most noteably, the lateral cervical ligs and important
Discuss the boundaries of Scarpa's fascia and its derivatives with respect to the containment of urine.
Specify the fascial layers associated with the accumulation of urine. Discuss whether urine will be found in the ischiorectal fossa. (12 pts)
- General comments: Scarpa's fascia is membranous tela subcutanea. This fascia is capable of holding sutures and defines a potential space
between it and deep fascia. This space can be invaded by infection or the extravasation of urine. The tear in the inferior fascia of the urogenital
diaphragm transmits urine from the deep pouch to the superficial perineal pouch. The intact superior fascia of the urogenital diaphragm together with
the intact superficial perineal fascia will prevent urine from entering the ischiorectal fossa. The accumulation of urine is restricted by the boundaries
of Scarpa's (membranous) fascia.
- Anterior abdominal wall - between Scarpa's fascia and deep fascia of external oblique
- superior: Scarpa's fascia attaches to deep fascia in finger like projections at level of umbilicus
- inferior medial: open passage to scrotum
- inferior lateral: passage to thigh
- lateral: near mid-axillary line at the thoracolumbar fascia
- medial: along the linea alba, fundiform ligament
- anterior: Scarpa's fascia
- posterior: deep fascia of external oblique
- Thigh - between Scarpa's fascia and fascia lata
- Inferior: 2 cm below inguinal ligament
- superior: open
- lateral: iliotibial tract
- medial: pubic ramus
- anterior: Scarpa's fascia
- posterior: fascia lata
- Scrotum - between Darto's tunic (Scarpa's derivative) and external spermatic fascia (deep fascia)
- superficial: Darto's tunic
- deep: external spermatic fascia
- Penis - between Colle's fascia (Scarpa's derivative) and Bucks fascia (deep fascia)
- extends distally toward base of, but not including, the glans
- superficial: Colle's fascia
- deep: Buck's fascia
- Urogenital triangle - within superficial pouch between superficial perineal fascia (derivative of Scarpa's fascia) and perineal membrane (deep fascia)
- superior: perineal membrane (inferior fascia of the urogenital diaphragm
- inferior: superficial perineal fascia
- anterior: open into scrotum
- posterior: posterior free edge of urogenital diaphragm, superficial perineal fascia
- lateral: conjoint rami
- medial: not restricted
- Extravasation into the ischiorectal fossa? - NO
- limited by superior fascia of UG diaphragm
- limited by superficial perineal fascia (attached to posterior free edge of UG diaphragm and conjoint rami)
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© Loren A. Evey, Ph.D.
The Structural Basis of Medical Practice - Human Gross Anatomy
The College of Medicine
of the The Pennsylvania State University
Email: lae2@psu.edu
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