Anatomy & Physiology

Anatomy & Physiology Study Guide

©2018 Achieve Page 271 The Abdominal Aorta The abdominal aorta, which begins immediately inferior to the diaphragm, is a continuation of the thoracic aorta. Descending slightly to the left of the vertebral column, but posterior to the peritoneal cavity, the abdominal aorta is commonly surrounded by a cushion of adipose tissue. At the level of vertebra L4, it splits into two major arteries—the left and right common iliac arteries—that supply deep pelvic structures and the lower limbs. The region where the abdominal aorta splits is called the terminal segment of the aorta. The abdominal aorta delivers blood to all the abdominopelvic organs and structures. The abdominal aorta gives rise to three unpaired arteries: • The celiac trunk takes blood to the liver, stomach, and spleen. The celiac trunk divides into three branches: the left gastric artery, which supplies the stomach and the inferior portion of the esophagus; the splenic artery, which supplies the spleen and arteries to the stomach (left gastroepiploic artery) and pancreas (pancreatic arteries); and the common hepatic artery, which supplies arteries to the liver (hepatic artery proper), stomach (right gastric artery), gallbladder (cystic artery), and duodenal area (gastroduodenal, right gastroepiploic, and superior pancreaticoduodenal arteries). • The superior mesenteric artery arises about 2.5 cm (1 in.) inferior to the celiac trunk to supply arteries to the pancreas and duodenum (inferior pancreaticoduodenal artery), small intestine (intestinal arteries), and most of the large intestine (right and middle colic and the ileocolic arteries). • The inferior mesenteric artery arises about 5 cm (2 in.) superior to the terminal aorta and delivers blood to the terminal portions of the colon (left colic and sigmoid arteries) and the rectum (rectal arteries). The abdominal aorta also gives rise to five paired arteries: • The inferior phrenic arteri s supply the inferior surface of the diaphragm and the inferior portion of the esophagus. • The suprarenal arteries originate on either side of the aorta near the base of the superior mesenteric artery. Each suprarenal artery supplies one suprarenal gland, which caps the superior part of a kidney. • The short renal arteries (about 7.5 cm) arise along the posterolateral surface of the abdominal aorta, about 2.5 cm (1 in.) inferior to the superior mesenteric artery, and travel posterior to the peritoneal lining to reach the suprarenal glands and kidneys. • The gonadal arteries originate between the superior and inferior mesenteric arteries. In males, they are called testicular arteries and are long, thin arteries that supply blood to the testes and scrotum. In females, they are termed ovarian arteries and supply blood to the ovaries, uterine tubes, and uterus. The distribution of gonadal vessels (both arteries and veins) differs by gender. • Small lumbar arteries arise on the posterior surface of the aorta and supply the vertebrae, spinal cord, and abdominal wall. Arteries of the Pelvis and Lower Limbs Near the level of vertebra L4, the terminal segment of the abdominal aorta divides to form a pair of elastic arteries—the right and left common iliac arteries—plus the small median sacral artery. The of 368