Abdominal aorta

The abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of descending aorta (of the thorax).

The abdominal aorta begins at the level of the diaphragm, crossing it via the aortic hiatus at the vertebral level of T11/T12. It travels down the posterior wall of the abdomen in front of the vertebral column. It thus follows the curvature of the lumbar vertebrae, that is, convex anteriorly. The peak of this convexity is at the level of the third lumbar vertebra (L3).

Branches

The abdominal aorta supplies blood to much of the abdominal cavity. It begins at T12, and usually has the following branches:

Inferior phrenic.
Celiac.
Superior mesenteric
Middle suprarenaL

Renal

Gonadal
Lumbar
Inferior mesenteric
Median sacral
Common iliac

Inferior phrenic

The inferior phrenic arteries are two small vessels, which supply the diaphragm but present much variety in their origin.
They may arise separately from the front of the aorta, immediately above the celiac artery, or by a common trunk, which may spring either from the aorta or from the celiac artery. Sometimes one is derived from the aorta, and the other from one of the renal arteries; they rarely arise as separate vessels from the aorta.
They diverge from one another across the crura of the diaphragm, and then run obliquely upward and lateralward upon its under surface.
The left phrenic passes behind the esophagus, and runs forward on the left side of the esophageal hiatus.
The right phrenic passes behind the inferior vena cava, and along the right side of the foramen which transmits that vein.
Near the back part of the central tendon each vessel divides into a medial and a lateral branch.
The medial branch curves forward, and anastomoses with its fellow of the opposite side, and with the musculophrenic and pericardiacophrenic arteries.
The lateral branch passes toward the side of the thorax, and anastomoses with the lower intercostal arteries, and with the musculophrenic. The lateral branch of the right phrenic gives off a few vessels to the inferior vena cava; and the left one, some branches to the esophagus.
Each vessel gives off superior suprarenal branches to the suprarenal gland of its own side. The spleen and the liver also receive a few twigs from the left and right vessels respectively.

Celiac artery

The celiac artery, also known as the celiac trunk and also spelled as coeliac, is the first major branch of the abdominal aorta. Branching from the aorta around the level of the T12 vertebra in humans, it is one of three anterior/ midline branches of the abdominal aorta (the others are the superior and inferior mesenteric arteries).

The celiac artery supplies oxygenated blood to the liver, stomach, abdominal esophagus, spleen and the superior half of both the duodenum and the pancreas. These structures correspond to the embryonic foregut. (Similarly, the superior mesenteric artery and inferior mesenteric artery feed structures arising from the embryonic midgut and hindgut respectively. Note that these three anterior branches of the abdominal aorta are distinct and cannot substitute for one another, although there are limited connections between their terminal branches.)
The celiac artery is an essential source of blood, since the interconnections with the other major arteries of the gut are not sufficient to sustain adequate perfusion. Thus it cannot be safely ligated in a living person, and obstruction of the celiac artery will lead to necrosis of the structures it supplies.

Superior mesenteric artery

the superior mesenteric artery (SMA) 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.

It arises anterior to vertebra L1 in an adult. It is usually 1cm lower than the celiac trunk. It initially travels in an anterior/inferior direction, passing behind/under the neck of the pancreas and the splenic vein.

Middle suprarenal arteries

The middle suprarenal arteries (middle capsular arteries; suprarenal arteries) are two small vessels which arise, one from either side of the abdominal aorta, opposite the superior mesenteric artery.
They pass laterally and slightly upward, over the crur of the diaphragm, to the suprarenaL glands, where they anastomose with suprarenal branches of the inferior phrenic and renal arteries.
In the fetus these arteries are of large size.

Renal arteries

The renal arteries normally arise off the side of the abdominal aorta, immediately below the superior mesenteric artery, and supply the kidneys with blood. Each is directed across the crus of the diaphragm, so as to form nearly a right angle with the aorta.
The renal arteries carry a large portion of total blood flow to the kidneys. Up to a third of total cardiac output can pass through the renal arteries to be filtered by the kidneys.
The arterial supply of the kidneys is variable and there may be one or more renal arteries supplying each kidney. It is located above the renal vein.

Gonadal artery

The term gonadal artery is a generic term for a paired artery, with one arising from the abdominal aorta for each gonad. Specifically, it can refer to:
the testicular artery in males
the ovarian artery in females

lumbar arteries

The lumbar arteries are in series with the intercostals.
They are usually four in number on either side, and arise from the back of the aorta, opposite the bodies of the upper four lumbar vertebræ.
A fifth pair, small in size, is occasionally present: they arise from the middle sacral artery.
They run lateralward and backward on the bodies of the lumbar vertebræ, behind the sympathetic trunk, to the intervals between the adjacent transverse processes, and are then continued into the abdominal wall.
The arteries of the right side pass behind the inferior vena cava, and the upper two on each side run behind the corresponding crus of the diaphragm.
The arteries of both sides pass beneath the tendinous arches which give origin to the Psoa major, and are then continued behind this muscle and the lumbar plexus.
They now cross the Quadratus lumborum, the upper three arteries running behind, the last usually in front of the muscle.
At the lateral border of the Quadratus lumborum they pierce the posterior aponeurosis of the Transversus abdominis and are carried forward between this muscle and the Obliquus internus.

Inferior mesenteric artery

the inferior mesenteric artery, often abbreviated as IMA, supplies the large intestine from the left colic (or splenic) flexure to the upper part of the rectum, which includes the descending colon, the sigmoid colon, and part of the rectum. Proximally, its territory of distribution overlaps (forms a watershed) with the middle colic artery, and therefore the superior mesenteric artery. The SMA and IMA anastomose via the marginal artery (artery of Drummond). The territory of distribution of the IMA is more or less equivalent to the embryonic hindgut.

median sacral artery

The median sacral artery (or middle sacral artery) is a small vessel, which arises from the back of the aorta, a little above its bifurcation.
It descends in the middle line in front of the fourth and fifth lumbar vertebræ, the sacrum and coccyx, and ends in the glomus coccygeum (coccygeal gland).
From it, minute branches are said to pass to the posterior surface of the rectum.
On the last lumbar vertebra it anastomoses with the lumbar branch of the iliolumbar artery; in front of the sacrum it anastomoses with the lateral sacral arteries, and sends offsets into the anterior sacral foramina.
It is crossed by the left common iliac vein, and is accompanied by a pair of venæ comitantes; these unite to form a single vessel, which opens into the left common iliac vein.

Common iliac arteries

The common iliac arteries are two large arteries, about 4cm long in adults but more than a centimetre in diameter, that originate from the aortic bifurcation. The arteries run inferolaterally, along the medial border of the psoas muscles to the pelvic brim, where they bifurcate into the external iliac artery and internal iliac artery. The common iliac artery, and all of its branches, exist as paired structures (that is to say, there is one on the left side and one on the right).
The distribution of the common iliac artery is basically the pelvis and lower limb (as the femoral artery) on the corresponding side.
Both common iliac arteries are accompanied along their course by common iliac veins.