The Aorta and Its Major Branches The aorta is the biggest artery in the body, with a diameter of approximately 3 cm (1 in.). All systemic arteries branch off the aorta. The aorta has four major segments: ascending aorta, arch of the aorta (or aortic arch), thoracic aorta, and abdominal aorta. Arteries that branch off each section of the aorta divide into smaller arteries that supply different organs. These arteries then divide into arterioles within the organs, and finally into capillaries that supply all systemic tissues accept the alveoli of the lungs. The Ascending Aorta The ascending aorta, which is approximately 5 cm (2 in.) long, is the first section of the aorta. It begins at the aortic valve, at the upper part of the base of the left ventricle. It has three dilations called aortic sinuses. The right and left coronary arteries originate from the right and left aortic sinuses. The posterior interventricular branch of the right coronary artery supplies the right and left ventricles. The right ventricle also receives blood from the second branch of the right coronary artery, the marginal branch. The left coronary artery has two branches: the anterior interventricular branch (left anterior descending branch), which supplies both ventricles, and the circumflex branch, which supplies the left ventricle and left atrium. The Arch of the Aorta The ascending aorta curves to the left and becomes the arch of the aorta, which is about 4–5 cm (2 in.) long. It runs downward and ends in front of the border between the fourth and fifth thoracic vertebrae. The arch of the aorta gives rise to three major branches: the brachiocephalic trunk, left common carotid artery, and left subclavian artery. Branches of the Arch of the Aorta Branch Area Supplied Description Brachiocephalic Right upper limb, Brachiocephalic trunk (brachiocephalic trunk head, neck artery) is the largest branch of the aortic arch; Gives rise to the right subclavian arteryand right common carotid artery Right subclavian Right upper limb, Runs from the brachiocephalic trunk and to the artery brain, spinal cord, first rib before passing into the armpit (axilla) neck, shoulder, thoracic viscera and wall, scapular muscles Internal thoracic Anterior thoracic The internal thoracic artery branches from the artery wall, mediastinum first part of the subclavian artery; Ends at the structures sixth intercostal space; Used to create the bypass for single coronary artery bypass grafting Vertebral artery Posterior part of The right vertebral artery branches off from the brain right subclavian artery and passes through the foramen magnum to reach the inferior surface of the brain; Joins with the left vertebral artery to form the basilar artery, branches of which Branch Area Supplied Description supply the cerebellum and pons of the brain, and the inner ear Axillary artery Shoulder, thoracic The axillary artery is the part of the subclavian and scapular artery that passes into the armpit; The same muscles, humerus vessel has different names as it passes through different areas of the body Brachial artery Upper limb The axillary artery becomes the brachial artery in the arm, where it is easy measure BP; To control bleeding, the brachial artery should be compressed near the middle of the arm Radial artery Radial (lateral) The radial artery is a direct continuation of the aspect of forearm, brachial artery very near the skin surface at the wrist, hand wrist, where the radial pulse is typically measured Ulnar artery Ulnar (medial) The ulnar artery is the larger of the two aspect of forearm, brachial artery branches; Reconnects with the wrist, hand smaller branch (the radial artery), in the palm, creating the superficial palmar arch and the deep palmar arch Superficial Branches supply Lies over the flexor tendons of the fingers and palmar arch palm and fingers extends to the palm; Gives rise to the common palmar digital arteries that perfuse the palm, each of which divides into a pair of proper palmar digital arteries that perfuse the fingers Deep palmar Branches supply Lies below the flexor tendons of the fingers and arch the palm and extends to the palm; Gives rise to palmar fingers metacarpal arteries that perfuse the palm and join with the common palmar digital arteries Right common Head and neck Begins where the brachiocephalic trunk divides carotid artery (right side) into its two branches; Divides into the right external and right internal carotid arteries; Often used to measure the pulse (at the side of the neck), for example, when exercising or administering cardiopulmonary resuscitation External carotid Face, scalp, neck Near the temporomandibular joint, the external artery carotid artery divides into the superficial Branch Area Supplied Description temporal and maxillary arteries; Used to detect the carotid pulse Internal carotid Orbital structures Branches of the internal carotid artery: artery (including the the anterior cerebral arteries supply parts of eyeball), ear, the frontal and parietal lobes; Branches merge cerebrum, pituitary with branches of the basilar artery— gland, external the posterior cerebral arteries(that supply the nose occipital lobes)—to form the cerebral arterial circle(circle of Willis) at the base of the brain; Posterior communicating arteries connect the posterior cerebral arteries with the internal carotid arteries; Anterior communicating arteriesconnect the anterior cerebral arteries; Cerebral arterial circle (which also includes the internal carotid arteries) equalizes BP in the brain and keeps blood flowing to the brain if other arteries are damaged Left common Head and neck The left common carotid artery branches from carotid artery (left side) the arch of the aorta and divides into branches with the same names as branches of the right common carotid artery Left subclavian Left upper limb The left subclavian artery branches from the artery arch of the aorta; Its branches and their names are similar to those of the right subclavian artery The Thoracic Aorta As the aorta continues its descent, it passes through the aortic hiatus, an opening in the diaphragm. The part of the aorta between the arch of the aorta and the diaphragm is called the thoracic aorta. It is approximately 20 cm (8 in.) long and starts at the border between the fourth and fifth thoracic vertebrae. The thoracic aorta gives rise to a number of small arteries. The visceral branches supply the viscera, and the parietal branches supply the body wall structures of the thorax. Branches of the Thoracic Aorta: Visceral Branch Area Supplied Description Pericardial Pericardium Two or three of these tiny pericardial arteries arteries perfuse the pericardium Bronchial Pleurae, bronchial Right bronchial artery branches from the arteries tubes, bronchial lymph third posterior intercostal artery; Two nodes, esophagus left bronchial arteries branch from the thoracic aorta Esophageal Esophagus Four or five esophageal arteries perfuse the arteries esophagus Mediastinal Mediastinum structures Numerous small mediastinal arteries arteries Branches of the Thoracic Aorta: Parietal Branch Area Supplied Description Branch Area Supplied Description Posterior Intercostal, pectoralis major and minor, Nine pairs of posterior intercostal and serratus anterior muscles; overlying intercostal arteries arteries subcutaneous tissue and skin; mammary glands; vertebrae, meninges, spinal cord Subcostal Same as the posterior intercostal arteries The subcostal arteries derive arteries their name from their location below the rib cage (costal, rib area) Superior Superior and posterior aspects of The small superior phrenic phrenic diaphragm arteries arise from the lower arteries part of the thoracic aorta The Abdominal Aorta The abdominal aorta is the part of the aorta between the diaphragm and its bifurcation (division into two branches) into the two common iliac arteries at the level of the fourth lumbar vertebra. The abdominal aorta is about 13 cm (5.1 in.) long. Like the thoracic aorta, the abdominal aorta gives off visceral and parietal branches. Branches of the Abdominal Aorta: Unpaired Visceral Branches Branch Area Supplied Description Celiac After emerging from the abdominal aorta, the celiac trunk trunk divides into the left gastric artery, splenic artery, and common hepatic artery Left gastric Stomach, Smallest of the three branches of the celiac trunk artery esophagus Splenic Branches supply Largest branch of the celiac trunk; Three artery pancreas, branches: pancreatic artery(supplies the pancreas), left stomach, greater gastroepiploic artery (stomach and greater omentum omentum), short gastric artery (stomach) Common Branches supply Intermediate-sized branch of the celiac trunk; Three hepatic liver, gall branches: proper hepatic artery (supplies the liver, artery bladder, stomach, and gall bladder), right gastric stomach, artery (stomach), gastroduodenal artery (stomach, duodenum, greater omentum, duodenum, and pancreas) pancreas, greater omentum Superior Branches supply The superior mesenteric artery runs between the layers Branch Area Supplied Description mesenteric duodenum, of mesentery; Five branches: inferior artery pancreas, parts pancreaticoduodenal artery (supplies the duodenum of small and and pancreas), jejunal artery (jejunum of small large intestines intestine),ileal artery (ileum of small intestine), ileocolic artery (ascending colon of large intestine), middle colic artery (transverse colon of large intestine) Inferior Branches supply The inferior mesenteric artery has three branches: left