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Lecture Notes - Peritoneal Cavity & Intestines |
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- Abdominal Cavity: The major part of the abdominopelvic cavity, bounded by the thoracic diaphragm and the pelvic inlet. It includes both the peritoneal cavity and the retroperitoneal space.
Peritoneal Cavity: That part of the abdomen surrounded by peritoneum. It is a potential space between the parietal and visceral layers of peritoneum.
Retroperitoneal Space: The area behind (posterior to) the peritoneum. Retroperitoneal organs are located in this space.- Abdominal Contents:
Peritoneum - A mesothelial lining of the abdominal cavity. The peritoneum has visceral and parietal layers, just like the pleural cavity.
Parietal - covers the abdominal wall
Visceral - forms surfaces of organs, the serosa.
Mesenteries: Portions of the peritoneum that suspend the gut and its derivatives and provide path for blood vessels and nerves to viscera.
OrgansIntraperitoneal: peritonealized organs having a mesentery, such as the stomach, small intestine (jejunum and ileum), transverse colon, liver and gallbladder.
Retroperitoneal: organs without a mesentery and associated with posterior body wall, such as the aorta, inferior vena cava, kidneys and suprarenal glands.
Secondarily retroperitoneal: organs which had a mesentery once and lost it during development, such as the pancreas, duodenum, ascending and descending colons.- Basic embryological considerations of gut development:
Gut developmentForegut - develops around celiac trunk: stomach to mid-duodenum, liver, pancreas, spleenPrimitive mesenteries
Midgut - develops around superior mesenteric artery: mid-duodenum to left colic flexure
Hindgut - develops around inferior mesenteric artery: left colic flexure to rectumDerivatives of the dorsal mesogastrium: the greater omentum (omental apron, gastrosplenic, gastrophrenic, gastrocolic, and splenorenal "ligaments")Rotation of the gut
Derivatives of the ventral mesogastrium: lesser omentum (hepatoduodenal and hepatogastric ligaments) and falciform ligament
Derivatives of the dorsal common mesentery: the mesentery, transverse mesocolon, sigmoid mesocolon, mesoappendix and mesocolon for ascending and descending colon (not in the adult).
Development of the omental bursa, omental (epiploic) foramen, fusion fascias, peritoneal regions and gutters such as subphrenic, para-, supra- and inframesocolic spaces and final peritoneal relationships of organs.- The small intestine (small bowel): duodenum, jejunum and ileum
Duodenum: secondarily retroperitoneal.
Jejunum and ileum
The mesentery
Vessels: Intestinal branches of superior mesenteric artery and vein, arcades and vasa rectae
Structural features: duodeno-jejunal flexure and suspensory ligament (of Treitz); circular folds; Meckel's diverticulum
- Large intestine (large bowel): Ascending, transverse, descending and sigmoid colon
Hepatic and splenic flexures
Ascending and descending colons: secondarily retroperitoneal
Mesenteries: transverse and sigmoid mesocolons, mesoappendix
Vessels:Structural features: Cecum, appendix, ileocecal valve, tenia, haustra and omental (epiploic) appendages
- superior mesenteric - ileocolic, right and middle colic
- inferior mesenteric - left colic, sigmoid and superior rectal
- marginal artery
- Nerves and Lymphatics:
Nerves: Preaortic autonomic plexuses and pelvic splanchnics
Lymphatics: Intestinal nodes draining to intestinal lymph trunk to cisterna chyli