24.25:
Abdominal Aorta
The abdominal aorta originates from the aortic hiatus in the diaphragm and extends down to the L4 vertebra. It further branches into the visceral and parietal branches.
The unpaired visceral arteries include the celiac trunk and the superior and inferior mesenteric arteries.
The celiac trunk divides into three main branches — the left gastric, splenic, and common hepatic arteries, supplying the stomach, liver, spleen, upper duodenum, and pancreas.
The superior mesenteric artery supplies blood to the majority of the small intestine, parts of the large intestine, and the pancreas.
The inferior mesenteric artery supplies blood to the distal part of the large intestine.
The paired visceral branches of the abdominal aorta are the suprarenal, renal, and gonadal arteries supplying blood to the kidneys and reproductive parts.
Among the parietal branches are the unpaired median sacral artery and the paired inferior phrenic and lumbar arteries.
The median sacral artery supplies blood to the sacrum, coccyx, and spinal nerves. The inferior phrenic arteries supply the diaphragm, while the lumbar arteries supply the lumbar vertebrae and abdominal wall.
24.25:
Abdominal Aorta
Once the aorta traverses the diaphragmatic plane at the aortic hiatus, it is known as the abdominal aorta. This anatomical structure is positioned leftward of the spinal column, encased within a cocoon of adipose tissue behind the peritoneal cavity. It terminates at the L4 vertebra, where it splits into the common iliac arteries. Prior to this bifurcation, the abdominal aorta gives rise to several vital branches.
The celiac trunk, a singular artery, divides into the left gastric artery, which nourishes the stomach and esophagus, the splenic artery, which supplies the spleen, and the common hepatic artery. This latter artery further branches into the hepatic artery proper for the liver, the right gastric artery for the stomach, the cystic artery for the gallbladder, and multiple branches that serve the duodenum and pancreas. Additionally, the abdominal aorta gives rise to two unpaired vessels, the superior and inferior mesenteric arteries. The superior mesenteric artery, arising roughly 2.5 cm below the celiac trunk, sends branches to the small intestine (duodenum, jejunum, and ileum), the pancreas, and a large section of the large intestine. The inferior mesenteric artery, starting about 5 cm above the common iliac arteries, supplies the distal segment of the large intestine and the rectum.
Significant paired arteries also originate from the abdominal aorta. These include the inferior phrenic arteries, the adrenal arteries, the renal arteries, the gonadal arteries, and the lumbar arteries. The inferior phrenic artery, mirroring a superior phrenic artery, nourishes the underside of the diaphragm. The adrenal artery, near the superior mesenteric artery, nourishes the adrenal glands. Each renal artery, emerging about 2.5 cm below the superior mesenteric arteries, supplies a kidney. The right renal artery is longer, reflecting the aorta's leftward position relative to the vertebral column. The gonadal artery, depending on gender, is named either the ovarian artery or the testicular artery (internal spermatic). The lumbar arteries, numbering four pairs, supply blood to the lumbar region, the abdominal wall, and the spinal cord.
At the L4 vertebra, the aorta bifurcates into the left and right common iliac arteries while continuing as the median sacral artery into the sacrum. These common iliac arteries supply blood to the pelvic region and lower limbs. They are divided into external and internal iliac arteries around the level of the lumbar-sacral articulation. Each internal iliac artery provides branches to the urinary bladder, pelvic walls, external genitalia, and the medial femoral region. In females, these arteries also supply blood to the uterus and vagina. The larger external iliac arteries primarily supply the lower limbs.