##Jejunum, Ileum and Superior Mesenteric Artery
Characteristics of Small Intestine
- It is a long, thin, and coiled tube-like structure.
- It is the primary site of nutrient absorption.
- It is approximately 20 feet long and has a diameter of 1 inch.
- It is divided into three main parts: duodenum, jejunum, and ileum.
Short Explanation of Jejunum and Ileum
- Jejunum: The middle part of the small intestine, located between the duodenum and ileum. It is narrower, longer, and more coiled than the ileum.
- Ileum: The last part of the small intestine, located between the jejunum and the large intestine. It is wider, shorter, and less coiled than the jejunum.
Key Points: Differences between Jejunum and Ileum
- Location: Jejunum (middle part), Ileum (last part)
- Diameter: Jejunum (smaller), Ileum (larger)
- Coiling: Jejunum (more coiled), Ileum (less coiled)
- Lymphatic Drainage: Jejunum (to mesenteric lymph nodes), Ileum (to ileocolic lymph nodes)
- Function: Jejunum (absorption of most nutrients), Ileum (absorption of vitamin B12 and bile salts)
Origin, Branches, and Distribution of Superior Mesenteric Artery (MSA)
- Origin: From the abdominal aorta, near the aortic hiatus of the diaphragm.
- Branches:
- Right colic artery: supplies the ascending colon.
- Middle colic artery: supplies the transverse colon.
- Left colic artery: supplies the descending colon.
- Ileocolic artery: supplies the cecum, appendix, and right half of the colon.
- Jejunal arteries: supply the jejunum.
- Ileal arteries: supply the ileum.
- Distribution: Supplies blood to the midgut region, including the duodenum, jejunum, ileum, and right half of the colon.
Lymphatic Drainage of Small Intestine
- Jejunum: drained by the mesenteric lymph nodes.
- Ileum: drained by the ileocolic lymph nodes.
Arterial Supply of Small Intestine
- Duodenum: supplied by the superior and inferior pancreaticoduodenal arteries.
- Jejunum: supplied by the jejunum arteries (branches of the superior mesenteric artery).
- Ileum: supplied by the ileal arteries (branches of the superior mesenteric artery).
Short Explanation of Superior Mesenteric Artery (MSA)
- It is a major artery that supplies blood to the midgut region.
- It is located behind the pancreas and in front of the duodenum.
- It is approximately 6 inches long and has a diameter of 0.5 inches.