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.
Organs
Intraperitoneal: 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 development
Foregut - develops around celiac trunk: stomach to mid-duodenum, liver, pancreas, spleen
Midgut - develops around superior mesenteric artery: mid-duodenum to left colic flexure
Hindgut - develops around inferior mesenteric artery: left colic flexure to rectum
Primitive mesenteries
Derivatives of the dorsal mesogastrium: the greater omentum (omental apron, gastrosplenic, gastrophrenic, gastrocolic, and splenorenal "ligaments")
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).
Rotation of the gut
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:
- superior mesenteric - ileocolic, right and middle colic
- inferior mesenteric - left colic, sigmoid and superior rectal
- marginal artery
Structural features:
Cecum, appendix, ileocecal valve,
tenia, haustra and omental (epiploic) appendages
Nerves and Lymphatics:
Nerves: Preaortic autonomic plexuses and pelvic splanchnics
Lymphatics: Intestinal nodes draining to intestinal lymph trunk to cisterna chyli
Diaphragm
- Central tendon and Muscular part
- Crura - right and left crus
- Arcuate ligaments
- median arcuate ligament - aortic hiatus
- medial arcuate ligament - over psoas major muscle
- lateral arcuate ligament - over quadratus lumborum
Posterior abdominal wall (Retroperitoneum)
- Muscles - quadratus lumborum, psoas major, (psoas minor), and iliacus
- Lumbar plexus
- iliohypogastric n.
- ilioinguinal n.
- genitofemoral n.
- lateral femoral cutaneous n.
- femoral n.
- obturator n.
- Abdominal aorta and its branches
- Inferior vena cava and its branches
- Nerves
- Sympathetic nerves
- sympathetic trunk
- thoracic and lumbar splanchnic nerves
- Parasympathetic nerves
- anterior and posterior vagal trunks - to the splenic flexure of the colon
- pelvic splanchnic nerves (S2, S3, S4) - distal to the splenic flexure
- Preaortic autonomic plexuses and ganglia
- Lymphatic - Cisterna chili and thoracic duct
