The superior mesenteric artery (french : artère mésentérique supérieure) arises from the anterior surface of the aorta, on the middle line, at 2 cm below the origin of the coeliac artery, nearly at the level of the disc between the second and third lumbar, vertebras.
From its origin, it heads bottomward and frontward, ahead of the aorta, behind the pancreas on the posterior surface of which it traces a print which separates the collar from the body of this gland. Between the superior mesenteric artery and the aorta passes the left renal vein.
On the right, the superior mesenteric artery is in contact with the head of the pancreas; on the left, it follows the flat rim of the duodeno-jejunal angle. It is surrounded by a very dense, fibrous formed network of elastic fibers and abundant nervous nets; this network joins it together with the cœliac artery which dominates it. Soon the superior mesenteric artery emerges below the lower edge of the pancreas, perpendicularly crosses the former surface of the third part of the duodenum, against which it is directly applied.
It engages then in the thickness of the root of the mesentery, to go down obliquely on the right up to the level from the opening of the iléon in the large intestine where it ends by anastomosing with the ileal branch of the ileocolic artery. From 23 to 25 cm long, the superior mesenteric artery makes an arcade with its convexity turned on the left and ahead.
Branches of the superior mesenteric artery
By the convexity of its arcade, the superior mesenteric artery emits a great number of branches, the intestinal arteries ; from the concavity of this arcade arises the right colic arteries.
The intestinal arteries are of two orders the bulkiest, ten to twelve, are detached from the initial part of the arcade; the smallest, eight to twelve, emanate from the final portion of the artery. These branches walk on between the two layers of the mésentère; after a way from 7 to 8 cm. for the big ones, 3 to 5 cm. for the small ones, they are forked. The branches of junction are anastomosed with those of the close intestinal arteries and thus form a first series of arcades, with convexity turned towards the intestine. These arcades start from new parallel branches, forty to fifty, which are forked in their turn and whose branches form, while anastomosing itself, a second series of arcades, close to the edge mesenteric of the intestine. The ramuscules which are born from this second series of arcades form, in the same way, a third series of arcades from which leave the final branches, former and posterior, which are distributed in the walls of the intestine.
By its concavity, the superior mesenteric artery gives the left duodenopancreatic artery (inferior pancreaticoduodenal artery of the classics); the right colic arteries.
Left duodenopancreatic artery
The left duodenopancreatic artery arises from the superior mesenteric artery to the point where it skirts the right side of the ascending portion of the duodenum and goes down along the left half of the duodenal ring; it is distributed to the duodenum, incidentally to the pancreas.
Right colic artery
These arteries, which go to the right half of the large intestine, are two or three.They are referred under the generic term of colics and one distinguishes them, in general, by the epithets of higher or ascending, average or transverse, lower or downward. According to the portion of the large intestine to which they go, they can be described as follows:
Artery of the transverse colon (colic superior of some authors), ascending of some others, middle colic of the Germans).
It is born from mesenteric in concavity from the ring duodénal, penetrates in the thickness of the transverse méso-colonist. moves ahead and slightly on the right and within a few centimetres of the edge mesenteric of the transverse colon divides into two branches the right branch anastomizes with the artery of the ascending colon , the left branch with that of the downward colon.
Artery of the ascending colon (right, transverse colic middle)
It arises directly from the trunk of the superior mesenteric or one of the two other colics thus the number of colic arteries can be reduced to two. It moves on the right and a little in the bottom, passes under the duodenum and divides before reaching the ascending colon in two branches, the upper of which anastomizes with the artery of transverse colon and the lower with ileocolic.
Artery ileocolic or ileocolocaecal (lower colic, downward).
It finishes the arcade formed by the superior mesenteric, and goes down on the right, towards the ileocolic angle where it is divided into branches going to the caecum and the ileon.
As it is seen, the superior mesenteric artery irrigates all the small intestine and half of the large intestine; the branches of the small intestine arise from the convexity of its arcade, those of the large intestine are detached from the concavity of this arcade.
Superior mesenteric artery
The distance which separates the origin from the caeliac artery of the superior mesenteric artery is more considerable, absolutely and relatively, in the fetus and the child than in the adult, which would result from the fact the segment of intermediate aorta would be to some extent absorbed in the walls of the two vessels. Thus would be explained the abnormal cases where the superior mesenteric artery comes from the caeliac artery.
The higher mesenteric artery often provides supernumerary branches. One saw it giving the hepatic artery, or the right branch of this artery, the cystic artery, an additional cystic artery, the renal artery, the gastroduodenal artery or one of the collateral of this artery, an anastomotic branch for the hepatic artery arising abnormally from the abdominal aorta, the coronary stomachic one, an additional pancreaticoduodenal artery, the left colic artery and the superior hémorroidal artery, several additional colic arteries.
Persistence of the omphalo mesenteric artery
It is known that in the embryo, the superior mesenteric artery represents the intestinal branch of the omphalo-mesenteric artery. Whose umbilical branch will ramify on the umbilical blister. Normally this umbilical, satellite branch from the diverticulum of Meckel, disappears about the second month from the intra-uterine life. But it can persist.