Covers the small intestine's length, width and extent from the pylorus to the ileocaecal junction, then its three parts: duodenum, jejunum and ileum. It explains how the organ is fixed by the mesentery and its root, and gives the four wall layers. The duodenum is described part by part, with its blood supply, venous and lymphatic drainage and innervation. A closing comparison contrasts the jejunum and ileum in diameter, length, wall thickness, vasa recta, arcades and mesentery.
Topic 54 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 10 sections, about 556 words (4 min of reading), with 20 flashcards.
In this note
SMALL INTESTINE
Parts :
Fixation :
Histology :
DUODENUM
Blood supply:
Innervation:
JEJUNM & ILEUM
Jejunum :
Ileum :
SMALL INTESTINE
The small intestine is the longest part of the digestive system.
Approximately 3 - 5 m long and its width is 2 - 4 cm
* Is the primary site for absorption of nutrients from ingested material.
Extends from the pylorus of the stomach to the ileocaecal junctior
Parts :
(1) Duodenum
(2) Jejunum
(3) Ileum
Fixation :
The small intestine is fixed and supported within the abdominal cavity by several structures, preventing excessive movement and ensuring proper function.
1. Mesentery : double layer fold of the peritoneum
The small intestine is connected to the posterior abdominal wall by it.
2. Root of menestry:
the attachment of the mesentery to the posterior abdominal wall
extends from the duodenojejunal flexure to the right iliac fossa.
Histology :
4 layers:
1. Mucosa : lined by Simple columnar epithelium . with valve
2. Submucosa : Connective tissue layer
3. Muscular Externa : smooth muscle layer
inner (circular) ↔ outer (longitudinal)
4. Serosa .
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