Human Anatomy and Intenstines

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The large intestine which encircles the small intestines consists of the cecum; appendix; ascending, transverse, descending and sigmoid colon; rectum; and anal canal1. The large intestine differs from the small intestine anatomically by the presence of four features1:
1. Omental appendices: omental-like peritoneum covered fat accumulations
2. Teniae coli: thickened bands of smooth muscle which begins at the base of the appendix as one one band and then separates into three bands to run the length of the rest of the large intestine up until the recto-sigmoid junction where they once again become a merged longitudinal layer around the rectum
3. Haustra: sacculation/pouches within the semilunar folds
4. Internal diameter/ caliber is greater in the large intestine

Cecum and Appendix
The cecum; roughly 7.5 cm in length and in breadth is a blind intestinal pouch, and it forms the first part of the large intestine1. It is inferior to the ileocecal junction and it lies in the right inguinal region/ iliac fossa1. It is an intraperitoneal structure however it has no mesentery1. It is held in place in the right iliac fossa by one or more cecal folds of the peritoneum1.
The relationships of the cecum1: o Continuous with ascending colon at the level of the opening of the ileum on the medial side o In contact with the anterior abdominal wall o The appendix is attached on the posteromedial wall o Superior to the inguinal ligament; within 2.5cm; and resting posteriorly on the right iliac fossa.
The vermiform appendix meaning worm-like is on average a 6-10cm long narrow and blind ended tube that arises on the posteromedial aspect of the cecum inferior to the ileocecal junction1. It is suspended from the terminal ileum by a short triangu...

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... along the left colic artery1. It then passes to the inferior mesenteric lymph nodes1. Lymph from the left colic flexure may drain into the superior mesenteric lymph nodes or the inferior mesenteric lymph nodes1.
Innervation distal to the left colic flexure has sympathetic nerve supply from the lumbar part of the sympathetic trunk via the lumbar/ abdominopelvic splanchnic nerves, the superior mesenteric plexus, and the peri-arterial plexuses following the inferior mesenteric artery and its branches1. Parasympathetic nerve supplies form the pelvic splanchnic nerves via the inferior hypogastric plexus and nerves1.

Works Cited

1. Moore KL, Dalley AF, Agur AMR. Clinically Orientated Anatomy. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2010. p.246-253; 411-414.
2. Netter, FH. Atlas of Human Anatomy. 5th ed. Philadelphia: Saunders Elsevier; 2009. Plate 373.

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