University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

145

Pages:

3
Author:

Mariam A. A.

Jejunum and Ileum Position • The jejunum begins at the duodenojejunal flexure where the gastrointestinal tract resumes an intraperitoneal course • The ileum ends at the ileocecal junction the union of the terminal ileum and he cecum • The jejunum constitutes 2/5ths • The ileum constitutes 3/5ths • Most of the jejunum lie sin the left upper quadrant of the infracolic compartment • Most of the ileum lies in the right lower quadrant Mesentery • Fan shaped fold of peritoneum that attaches the jejunum and ileum to the posterior abdominal wall • The origin or root of the mesentery is directly obliquely, inferiorly and to the right • Extends from the duodenojejunal junction on the left side of the vertebra L2 to the ileocolic junction and the right sacro-iliac joint • The root of the mesentery crosses (successively) the ascending and inferior parts of the duodenum, abdominal aorta, IVC, right ureter, right psoas major, and right testicular or ovarian vessels • Between the two layers of the mesentery are the superior mesenteric vessels, lymph nodes, a variable amount of fat, and autonomic nerves. Meckel’s Diverticulum • Congenital defect found in 2% of the population • Meckel's diverticulum is an outpouching or bulge in the lower part of the small intestine Blood Supply Superior mesenteric artery Supplies jejunum and ileum via jejunal and ileal arteries Arises from abdominal aorta at the level of L1 About 1cm inferior to the celiac trunk and runs between the layers of the mesentery sending 15-18 branches to the jejunum and ileum These arteries unite to form loops or arches “arterial arcades” which give rise to straight arteries called vasa recta Double row of arterial arcades in the ileum Anterior to the SMA: pyloric part of the stomach, splenic vein and neck of pancreas Posterior to the SMA: left renal vein, uncinate process of the pancreas and inferior part of the duodenum ✓ The uncinate process is the only part of the pancreas that hooks around the back of the SMA • Venous Drainage Venous arcades drain to the superior mesenteric vein Innervation • Sympathetic: Celiac and superior mesenteric sympathetic trunks • Parasympathetic: Vagus nerve