Created by Merike Mikkov
about 9 years ago
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Question | Answer |
Where does the duodenum begin and end | Begins: at the pyloric sphincter Ends: at the duodenojejunal flexure |
How long are the different parts of the small intestine? | Duodenum - 25 cm Jejunum - 2.5 m Ileum - 3.5 m |
Define and describe the mesentery | A fan-shaped fold of peritoneum that attaches jejunum and ileum to the posterior abdominal wall. Contains superior mesenteric vessels, lymph nodes, fat and autonomic nerves |
Describe the blood supply to the jejunum and the ileum | Superior mesenteric artery supplies the jejunum and ileum via jejunal and ileal arteries. SMA arises from the abdominal aorta at the level of L1. Sends 15-18 branches to the jejunum and ileum. These arteries unite to form arches called arterial arcades which give rise to straight arteries called vasa recta. |
Describe the venous drainage of the jejunum and the ileum | Superior mesenteric vein drains the jejunum and ileum. SMV ends posterior to the neck of the pancreas where it unites with the splenic vein to form the hepatic portal vein. |
Describe the lymphatic drainage of the small intestine | Specialised lymphatic vessels in the villi - lacteals. Absorb fat and empty the fluid into lymphatic plexuses in the walls of the jejunum and ileum which drain into lymphatic vessels in the mesentery. Within the mesentery the lymph passes through three groups of lymph nodes: • Juxta-intestinal lymph nodes (close to intestinal wall) • Mesenteric lymph nodes (among arterial arcades) • Superior central nodes (proximal part of the SMA) Lymphatic vessels from the terminal ileum follow the ileal branch of the ileocolic artery to the ileocolic lymph nodes. |
Describe the nervous supply to the small intestine | SMA and its branches are surrounded by a periarterial nerve plexus through which the nerves are conducted to the parts of the intestine supplied by this artery. Sympathetic fibres - T8-T10 segments to the superior mesenteric nerve plexus. Parasympathetic fibres in the nerves derive from the posterior vagal trunks. |
Compare and contrast the appearance of jejunum and ileum | |
Name the characteristic lymphoid tissue prevalent in ileum | Peyer's patches |
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