Small and Large Intestines Flashcards
Click on Answer for diagrams on lymphatics of the abdomen.
The jejunum and ileum are suspended from the posterior abdominal wall by a large fold of peritoneum called the ____________; hence, the small intestine enjoys a considerable mobility.
mesentery of the small intestine
What structures does the root of the mesentery cross?
the third part of the duodenum, the abdominal aorta, the inferior vena cava, the right ureter, and the right psoas major muscle [Diagram]
State the extents of the mesentery.
It is attached to the posterior abdominal wall, extending from the duodenojejunal flexure to the ilieocaecal junction. [The duodenojejunal flexure lies to the left side of second lumbar vertebra, whereas ileocaecal junction lies at the right sacroiliac joint.]
Briefly discuss the sympathetic and parasympathetic innervation of the small intestine.
Sympathetic supply is derived from T10-T11 spinal segments through splanchnic nerves and the superior mesenteric plexus. For this reason, pain from the jejunum and ileum is referred to the umbilical region.
The parasympathetic supply is derived from the vagus nerves through the coeliac and superior mesenteric plexuses.
State the arterial supply of the ileum and jejunum.
The jejunum and ileum are supplied by the jejunal and ileal branches (12–15 in number) of the superior mesenteric artery. They arise from the left side of the superior mesenteric artery and enter the mesentery to reach the intestine. The terminal part of the ileum is supplied by the ileal branches of the ileocolic branch of the superior mesenteric artery. As soon as these enter the mesentery they break up into smaller branches which anastomose with each other to form a series of arterial arcades which are more complex in the ileum than in the jejunum.
Discuss the venous drainage of the ileum and jejunum.
The veins correspond to the branches of superior mesenteric artery and drain into the portal vein, which carries the products of protein and carbohydrates to the liver.
Further notes:
The superior mesenteric artery is a major artery that arises from the anterior surface of the abdominal aorta, just inferior to the origin of the celiac trunk.
State four functions of the large intestine.
(a) Absorption of water from fluid contents in it to help form the feces.
(b) Storage, lubrication, and expulsion of feces.
(c) Synthesis of vitamin B complex by normal bacterial flora present its lumen.
(d) Protection from invasion by microorganisms by its mucoid secretion which is rich in IgA group of antibodies.
State the four parts of the large intestine.
(a) Caecum and appendix
(b) Colon
(c) Rectum
(d) Anal canal
Name and briefly discuss the three cardinal features of the large intestine.
(a) teniae coli: these are three separate longitudinal ribbons of smooth muscle located along the length of most of the large intestine.
[Cadaveric image] [Diagram] [Diagram 2]
(b) appendices epiploica: these are small bags of visceral peritoneum filled with fat attached to teh teniae of large intestine.
[Diagram] [Diagram 2]
(c) saccultions/haustrations: these are a series of pouches/dilatations in the wall of the caecum and colon between the teniae.
[Diagram]
State the anterior relations of the caecum.
(a) Coils of the small intestine
(b) Greater omentum
(c) Anterior abdominal wall (in the right iliac region)
State the posterior relations of the caecum.
(a) Right psoas major and iliacus muscles
(b) Femoral nerve, lateral cutaneous nerve of thigh, and genitofemoral nerve of the right side
(c) Right gonadal vessels
[Diagram]
Further notes:
The genitofemoral nerve pierces and passes through the psoas major muscle.
The ____________ valve regulates the flow of contents from the ileum to the caecum and prevents regurgitation of the caecum into the ileum.
iliocaecal
