#mesenteries

~ Weeks 4 through 6

Three embryologic divisions of the thoracic and abdominal gastrointestinal tube:

Foregut

Supplied by the celiac artery

Gives rise to the:

Esophagus

Stomach - Liver buds, which ultimately form the liver

Gallbladder

Ventral and dorsal pancreatic buds (aka, diverticula), which will later fuse to form the pancreas

Proximal duodenum

Midgut

Supplied by the superior mesenteric artery

Comprises primary intestinal loop, which connects to the yolk sac via the vitelline duct

Gives rise to the:

Distal duodenum

Jejunum

Ileum

Ascending colon

Proximal 2/3 of the transverse colon

Hindgut

Supplied by the inferior mesenteric artery

Gives rise to the allantois before ending blindly at the cloaca

Gives rise to the:

Distal 1/3 of the transverse colon - Descending and sigmoid colons

The proximal 2/3 of the anorectal canal

INNERVATION

The enteric nervous system, which is derived from neural crest cells, regulates motility to propel the contents of the GI tract.

MESENTERIES

Mesenteries divide the peritoneal cavity and suspend the gastrointestinal tract. Additionally, they provide a protective covering for neurovascular structures.

The ventral mesentery is derived from the septum transversum, and will give rise to ligaments associated with the liver.

The dorsal mesentery secures the gastrointestinal tract to the posterior body wall.

The meso-esophagus attaches the esophagus to the dorsal wall

The mesogastrium anchors the stomach

The mesoduodenum anchors the duodenum

The mesentery proper anchors the primary loop of the midgut