The intestinal arteries arise from the convex side of the superior mesenteric artery

Superior mesenteric artery

In human anatomy, the superior mesenteric artery arises from the anterior surface of the abdominal aorta, just inferior to the origin of the celiac trunk, and supplies the intestine from the lower part of the duodenum through two-thirds of the transverse colon, as well as the pancreas.-Location...

. They are usually from twelve to fifteen in number, and are distributed to the jejunum

Jejunum

The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum.The jejunum lies between the duodenum...

 and ileum

Ileum

The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum.The ileum follows the duodenum...

.

Nomenclature

The term "intestinal arteries" can be confusing, because these arteries only serve a small portion of the intestines.

• They do not supply any of the large intestine
  Large intestine
  The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
  
  . The large intestine is primarily supplied by the right colic artery
  Right colic artery
  The Right Colic Artery arises from about the middle of the concavity of the superior mesenteric artery, or from a stem common to it and the ileocolic....
  
  , middle colic artery
  Middle colic artery
  The middle colic artery is a branch of the superior mesenteric artery that mostly supplies the transverse colon. It arises just below the pancreas, and, passing downward and forward between the layers of the transverse mesocolon, divides into two branches: right and left.* The right branch...
  
  , and left colic artery
  Left colic artery
  The left colic artery is a branch of the inferior mesenteric artery that runs to the left behind the peritoneum and in front of the psoas major muscle, and after a short, but variable, course divides into an ascending and a descending branch; the stem of the artery or its branches cross the left...
  
  .
• They do not supply the duodenum
  Duodenum
  The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...
  
   of the small intestine
  Small intestine
  The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
  
  . The duodenum is primarily supplied by the inferior pancreaticoduodenal artery
  Inferior pancreaticoduodenal artery
  The inferior pancreaticoduodenal artery is a branch of the superior mesenteric artery or from its first intestinal branch, opposite the upper border of the inferior part of the duodenum....
  
   and superior pancreaticoduodenal artery
  Superior pancreaticoduodenal artery
  The superior pancreaticoduodenal artery is an artery that supplies blood to the duodenum and pancreas. It is a branch of the gastroduodenal artery, which most commonly arises from the common hepatic artery of the celiac trunk...
  
  .

For clarity, some sources prefer instead using the more specific terms ileal arteries and jejunal arteries.

Path

They run nearly parallel with one another between the layers of the mesentery

Mesentery

In anatomy, the mesentery is the double layer of peritoneum that suspends the jejunum and ileum from the posterior wall of the abdomen. Its meaning, however, is frequently extended to include double layers of peritoneum connecting various components of the abdominal cavity.-Mesentery :The...

, each vessel dividing into two branches, which unite with adjacent branches, forming a series of arches (arterial arcades

Arterial arcades

Arterial arcades are loops of arteries around the jejunum and ileum.Nearest the duodenum the mesenteric loops are primary, the vasa recta are long and regular in distribution, and the translucent spaces are extensive....

), the convexities of which are directed toward the intestine.

From this first set of arches branches arise, which unite with similar branches from above and below and thus a second series of arches is formed; from the lower branches of the artery, a third, a fourth, or even a fifth series of arches may be formed, diminishing in size the nearer they approach the intestine.

In the short, upper part of the mesentery only one set of arches exists, but as the depth of the mesentery increases, second, third, fourth, or even fifth groups are developed.

The differences between the ileal arteries and the jejunal arteries can be summarized as follows:

Type

Appearance

Number of arcades

Layer of fat >- | jejunal arteries

one (or few)

>- | ileal arteries

many

thick

From the terminal arches numerous small straight vessels (vasa recta

Vasa recta (intestines)

For the kidney structure, see vasa rectaVasa recta are straight arteries coming off from arcades in the mesentery of the jejunum and ileum, and heading toward the intestines....

) arise which encircle the intestine, upon which they are distributed, ramifying between its coats.

From the intestinal arteries small branches are given off to the lymph glands and other structures between the layers of the mesentery.