Superior Mesenteric Artery
Superior mesenteric artery is one of the major arteries of the alimentary canal. It supplies a large portion of the human digestive system including; part of duodenum, jejunum, ileum, cecum, appendix, ascending colon and most of the transverse colon.
Origin and course of superior mesenteric artery:
The superior mesenteric artery arises from the front of abdominal aorta just below the celiac artery. It then runs downward and to the right behind the neck of the pancreas and in front of the third part of duodenum. It continues downward to the right between the layers of the mesentery of small intestine and ends by anastomosing with the ileal branch of the ileocolic artery, which is its own branch.
Branches of superior mesenteric artery:
As described above, the superior mesenteric artery supplies a large portion of the alimentary canal. It does so through a number of branches, described below.
Inferior pancreaticoduodenal artery:
It may be single or double (anterior and posterior pancreaticoduodenal arteries), passing to the right along the upper border of the third part of duodenum and head of pancreas. As the name indicates, it supplies the pancreas and the adjoining part of duodenum.
Middle colic artery:
It is the artery of the middle part of colon, which is the transverse colon. It reaches the transverse colon from its origin by running forward in transverse mesocolon. It gives off right and left branches, which supply to corresponding portion of the transverse colon.
Right colic artery:
Often, the right colic artery is a branch of the ileocolic artery (see below). It supplies the ascending colon through two branches: ascending branch and descending branch.
It is one of the major branches of the superior mesenteric artery. It passes downward and to the right and divides into a superior branch and an inferior branch. The superior branch anastomoses with the right colic artery while the inferior branch anastomoses with the terminating party of the inferior mesenteric artery itself.
The inferior branch, in addition, gives rise to anterior and posterior cecal arteries, which supply the cecum.
Jejunal and ileal branches of superior mesenteric artery:
These are 12 to 15 in number, all of which arise from the left side of the superior mesenteric artery. It should be appreciated that no other branch arises from the left side of the artery.
Each branch divides into two vessels, which unite with adjacent branches to form a series of arcades. These arcades give additional branches, which unite again to form second, third and fourth series of arcades. Small straight vessels from the arcades supply jejunum and ileum. It should be kept in mind that in the region of jejunum, there is only one or at most two series of arcades, while in the region of ileum, there may be up to four series.