Branches of the thoracic aorta and the subclavian and axillary arteries provide blood throughout the thoracic region, which consists of 12 out of the 24 bones in the spine, which connects the neck to the lower back. The thoracic aorta runs from behind the aortic arch to a diaphragm opening called the aortic hiatus. Its visceral branches supply the viscera, or organs, and its parietal branches supply bones, muscles, and the layer of the chest wall that is made of skin. Three bronchial arteries connect to the visceral pleura (lung membrane), lung bronchi, and the esophagus. The esophageal arteries supply the esophagus, and the mediastinal arteries supply the mediastinum, the membrane between lungs. There are three parietal branches of the thoracic aorta. Nine pairs of posterior intercostal arteries spread through the back of the rib cage and then connect to anterior intercostal arteries. They supply some thoracic and abdominal muscles, skin, tissues, breasts, and spinal cord. Two subcostal arteries arise below rib 12. They supply deep back muscles, vertebrae, spinal cord, and posterior intercostal tissues. Superior phrenic arteries provide blood to the diaphragm.
Blood is supplied to the thoracic wall by four arteries. The internal thoracic (mammary) artery arises from the subclavian artery, and the others arise from the axillary artery. The internal thoracic (mammary) artery branches from the subclavian artery and supplies breasts, the anterior thoracic wall, and—through branches—the diaphragm and abdominal wall. From it arises the pericardiophrenic artery—which supplies the fibrous membrane that encloses the heart, or pericardium, and diaphragm—and the anterior intercostal arteries, which supply ribs and intercostal muscles. Several arteries branch from the axillary artery. The thoracoacromial trunk supplies the shoulder and pectoral region. The lateral thoracic artery provides blood to the lateral thoracic wall, and the subscapular artery supplies the scapula, posterior thoracic wall, and latissimus dorsi muscles.
The celiac trunk supplies blood to abdominal organs through three major subdivisions that branch from it, the common hepatic, left gastric, and splenic arteries. The common hepatic artery itself includes two primary branches. The gastroduodenal artery supplies the stomach and then meets the right gastroepiploic artery. It continues as the inferior pancreaticoduodenal artery, which supplies the pancreas and duodenum, and then meets with the superior mesenteric artery. The proper hepatic artery continues from the common hepatic, supplying the liver and gallbladder. The left gastric artery provides blood to the stomach and lower esophagus and then curves around the stomach. It becomes the right gastric artery and supplies the duodenum and stomach and then meets the proper hepatic artery. The splenic artery arising from the celiac trunk supplies blood to the spleen, branching along its path to form the pancreatic arteries, which supply the pancreas, and the left gastroepiploic artery. The latter, which supplies blood to the stomach, curves around to become the right gastroepiploic artery before meeting the gastroduodenal artery.
The superior and inferior mesenteric arteries provide circulation for the mesentery, which attaches abdominal organs to the posterior abdominal wall. Four branches of the superior mesenteric artery supply the small intestine, much of the large intestine, including the colon, and other organs. These are the inferior pancreaticoduodenal artery, intestinal arteries, ileocolic artery, right colic artery, and middle colic artery. Three branches of the inferior mesenteric artery supply the distal large intestine, including the rectum: left colic artery, sigmoid arteries, and superior rectal artery.