Lecture 4 - Mid Gut Flashcards
What is the second seciton of the small intestine?
jejunum
What is the third section of the small intestine?
Ileum
Where is the jejunum mostly found?
it is mostly found in the upper left quadrant
Function of jejunum?
It is intraperitoneal as it is highly movile and attaches to the posterior abdominal wall by the root of the mesentry. It also contains specialised epithelial lining for absorbing nutrients that have been digested. There is no clear change between the jejunum and the ileum.
Where is the ileum mostly found?
Mostly in the right lower quadrant
Function of the ileum?
It is intraperitoneal as the mesentry proper acts as a conduit for the neurovasculature. Also it absorbs any products of digestion that the jejunum missed.
What is the arterial supply to the jejunum and the ileum?
It is supplied by the vasa recta
Differences between the jejunum and the ileum?
Jejenum: deeper red, 2-4 cm diameter, thick and heavy, greater density of vascularity and longer vasa recta. Few large arterial arcades, Less mesenteric fat, large tall closely packed circular folds and few peyer’s patches.
Ileum: Pale pink, 2-3 cm in diameter, thin and light, lesser density of vascularity and short vasa recta nd many short arterial arcades, lots of mesenteric fat, low and sparse ciruclar folds and many peyer’s patches.
What is the arterial supply and venous drainage of the jejunum and the ileum?
Arterial supply - superior mesenteric artery that becomes the arterial arcades and that becomes the vasa recta
Venous drainage - drain into the superior mesenteric vein that geos into the hepatic portal vein that goes into the porrtal venous system.
Lymphatics and innervation of the jejunum and the ileum?
Lymphatics - drain by following the arteries towards the superior mesenteric lymph nodes
Innervation - parasympathetic - vagus, sympathetic - greater splanchnic and less splanchnic nerves
Parts of the large intestine?
- ) Ascending colon
- ) Transverse colon
- ) Descending colon
- ) Sigmoid colon
What is the teniae coli?
Three distinct bands of smooth muscle that run longitudinally. Begins at the appendix and they are named according to their position:
- ) Mesocolic tenia - where the trasnverse and sigmoid mesocolon attach
- ) Omental tenia - where the omental appendices attach
- ) Free tenia
They terminate by merging together at the rectosigmoid junction and contract lengthwise to form haustra.
What are the ommental appendices?
Small fatty prejections that are only found in the colon.
What is the haustra?
Contraction of the teniae coli cause a shorterning of the intestinal wall. Saccculations form as the wall becomes baggy and gathered. It is visible on the external surface and collectively these patches are called the haustra.
What are the semilunar folds?
These are the things that seperate the haustra internally by prominent ridges of mucose that are called the semi luanr folds. They are also known as the plicae semilunaris.
