Arteries are the large vessels that carry oxygenated blood away from the heart (except for the pulmonary circuit, in which the arterial blood is deoxygenated). The distribution of the systemic arteries is like a ramified tree, the common trunk of which, formed by the aorta, commences at the left ventricle, while the smallest ramifications extend to the peripheral parts of the body and the contained organs (see the image below).
The arteries, in their distribution, communicate with one another (forming what are called anastomoses) and end in minute vessels, called arterioles, which in their turn open into a close-meshed network of microscopic vessels, termed capillaries, the true deliverers of oxygen and nutrients to the cells.
Arteries are found in all parts of the body, except in the hairs, nails, epidermis, cartilages, and cornea. The larger trunks usually occupy the most protected situations; in the limbs, they run along the flexor surface, where they are less exposed to injury.
The aorta commences at the upper part of the left ventricle. After ascending for a short distance, it arches backward and to the left side; it then descends within the thorax on the left side of the vertebral column, passes into the abdominal cavity through the aortic hiatus in the diaphragm, and ends opposite the lower border of the fourth lumbar vertebra by dividing into the right and left common iliac arteries.
The ascending aorta commences at the upper part of the base of the left ventricle. At its origin, it presents (opposite the segments of the aortic valve) 3 small dilatations called the aortic sinuses. At the union of the ascending aorta with the aortic arch, the caliber of the vessel is increased. This dilatation is termed the bulb of the aorta. The only branches of the ascending aorta are the 2 coronary arteries, which supply the heart; they arise near the commencement of the aorta immediately above the attached margins of the semilunar valves.
The aortic arch forms 2 curvatures, one with its convexity upward and the other with its convexity forward and to the left. As the vessel runs backward, its left side is in contact with the left lung and pleura. Three branches are given off from the arch of the aorta: the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. The brachiocephalic trunk is the largest branch of the arch of the aorta and divides into the right common carotid and right subclavian arteries.
Descending thoracic aorta
The descending thoracic aorta is contained in the posterior mediastinum. At its commencement, it is situated on the left of the vertebral column. As it descends, it approaches the median line; at its termination, it lies directly in front of the column. The branches of this segment are divided into 2 sets, visceral (pericardial, bronchial, esophageal, and mediastinal) and parietal (subcostal, superior phrenic, and posterior intercostal). Usually, 9 pairs of posterior intercostal arteries arise from the aorta.
The abdominal aorta begins at the aortic hiatus of the diaphragm, in front of the lower border of the body of the last thoracic vertebra. It descends in front of the vertebral column and ends on the body of the fourth lumbar vertebra, commonly a little to the left of the midline, by dividing into the 2 common iliac arteries. The branches may be divided into 2 sets, visceral (celiac, superior mesenteric, inferior mesenteric, middle suprarenal, renal, testicular, and ovarian) and parietal (inferior phrenic, lumbar, middle sacral, terminal branches, and common iliac).
Arteries of trunk
The celiac trunk is a short thick trunk that arises from the front of the aorta, just below the aortic hiatus of the diaphragm. It passes forward nearly horizontally and divides into 3 large branches: the left gastric, the common hepatic (gastroduodenal and proper hepatic), and the splenic (pancreatic branches, short gastric branches, and left gastro-omental).
Superior mesenteric artery
The superior mesenteric artery is a large vessel that arises below the celiac artery and supplies the whole length of the small intestine, except the superior part of the duodenum; it also supplies the cecum, the ascending part of the colon, and the proximal two-thirds of the transverse colon. Its branches are the inferior pancreaticoduodenal, intestinal, middle colic, ileocolic, and right colic arteries.
Inferior mesenteric artery
The inferior mesenteric artery supplies the distal third of the transverse colon, the whole of the descending colon, the sigmoid colon, and the greater part of the rectum. Its branches are the left colic, sigmoid, and superior rectal arteries.
The renal arteries arise from the side of the aorta, immediately below the superior mesenteric artery. The right is longer than the left and passes behind the inferior vena cava, the right renal vein, the head of the pancreas, and the descending part of the duodenum. The left is higher than the right. Each vessel gives off some small inferior suprarenal branches to the suprarenal gland, the ureter, and the surrounding cellular tissue and muscles.
On the left side of the body of the fourth lumbar vertebra, the abdominal aorta divides into the 2 common iliac arteries. They diverge from the termination of the aorta, pass downward and laterally, and divide into 2 branches, the external iliac and internal iliac arteries. The former branch supplies the lower extremity; the latter supplies the viscera and muscles of the pelvis. The common iliac arteries give off small branches to the peritoneum, the psoas major, the ureters, and the surrounding areolar tissue; occasionally, they give rise to the iliolumbar or supernumerary renal arteries.
The internal iliac artery (hypogastric artery) supplies the muscles and viscera of the pelvis, the buttock, the external genitalia, and the medial side of the thigh. Its branches are from the anterior trunk (umbilical, obturator, uterine, vaginal, inferior vesical, middle rectal, internal pudendal, and inferior gluteal) and from the posterior trunk (iliolumbar, lateral sacral, and superior gluteal). The external iliac artery is larger than the internal iliac, and it gives off 2 branches, the inferior epigastric (immediately above the inguinal ligament) and the deep iliac circumflex, before passing beneath the inguinal ligament to become the femoral artery.
Arteries of head and neck
The principal arteries supplying the head and neck are the 2 common carotid arteries. These vessels ascend in the neck, where each divides into 2 branches, the external carotid (supplying the exterior of the head, the face, and the greater part of the neck) and the internal carotid (supplying to a great extent the parts within the cranial and orbital cavities).
The common carotid arteries differ in their mode of origin. The right begins at the bifurcation of the brachiocephalic trunk behind the sternoclavicular joint and is confined to the neck. The left springs from the highest part of the arch of the aorta to the left of, and on a plane posterior to, the brachiocephalic trunk. Each vessel passes obliquely upward, from behind the sternoclavicular articulation to the level of the upper border of the thyroid cartilage, where it divides into the external and internal carotid arteries. Behind the angle of bifurcation of the common carotid artery is a reddish-brown oval body known as the carotid body (glomus caroticum).
External carotid artery
The external carotid artery begins opposite the upper border of the thyroid cartilage. Taking a slightly curved course, it passes upward and forward, then inclines backward to the space behind the neck of the mandible. The branches of external carotid artery may be divided into 4 sets: anterior (superior thyroid, lingual, and facial), posterior (occipital and posterior auricular), ascending (ascending pharyngeal), and terminal (superficial temporal and maxillary). The maxillary artery is the larger of the 2 terminal branches of the external carotid; it supplies the deep structures of the face and may be divided into mandibular, pterygoid, and pterygopalatine portions.
Internal carotid artery
The internal carotid artery supplies the anterior part of the brain, as well as the eye and its appendages, and sends branches to the forehead and nose. In view of its course and relations, this vessel may be divided into 4 portions: cervical, petrous, cavernous, and cerebral. The cervical portion of the internal carotid gives off no branches. The petrous portion gives off the caroticotympanic and the artery of the pterygoid canal; the cavernous portion gives off the cavernous, hypophyseal, semilunar, and anterior meningeal; and the cerebral portion gives off the ophthalmic, anterior cerebral, middle cerebral, posterior communicating, and choroidal.
The cerebral arteries are derived from the internal carotid and vertebral, which form a remarkable anastomosis known as the cerebral arterial circle (of Willis) at the base of the brain. In front, this anastomosis is formed by the anterior cerebral arteries, branches of the internal carotid that are connected together by the anterior communicating artery. Behind, it is formed by the 2 posterior cerebral arteries, branches of the basilar that are connected on either side with the internal carotid by the posterior communicating artery.
Anterior cerebral artery
The anterior cerebral artery arises from the internal carotid at the medial extremity of the lateral cerebral fissure. It passes forward and medially across the anterior perforated substance, above the optic nerve, to the commencement of the longitudinal fissure. Here, it comes into close relationship with the opposite artery, to which it is connected by a short trunk, the anterior communicating artery. From this point, the 2 vessels run side by side in the longitudinal fissure, curve around the genu of the corpus callosum, and, turning backward, continue along the upper surface of the corpus callosum to its posterior part, where they end by anastomosing with the posterior cerebral arteries.
Middle cerebral artery
The middle cerebral artery, the largest branch of the internal carotid, runs at first laterally in the lateral cerebral or Sylvian fissure and then backward and upward on the surface of the insula, where it divides into a number of branches that are distributed to the lateral surface of the cerebral hemisphere. The branches of this vessel are the anterolateral ganglionic, inferior lateral frontal, ascending frontal, ascending parietal, parietotemporal, and temporal arteries.
Posterior cerebral artery and posterior communicating artery
The posterior communicating artery runs backward from the internal carotid and anastomoses with the posterior cerebral, a branch of the basilar. A number of small branches are given off from its posterior half--the posteromedial ganglionic branches, which, with similar vessels from the posterior cerebral, pierce the posterior perforated substance and supply the medial surface of the thalami and the walls of the third ventricle.
Anterior choroidal artery
The anterior choroidal artery is a small but constant branch that arises from the internal carotid, near the posterior communicating artery. It is distributed to the hippocampus, fimbria, tela choroidea of the third ventricle, and choroid plexus.
Arteries of upper limbs
The vessel that extends from its origin to the outer border of the first rib is termed the subclavian artery. From this point to the lower border of the axilla, it is named the axillary artery. From the lower margin of the axillary space to the bend of the elbow, it is termed the brachial artery; here, the trunk ends by dividing into 2 branches, the radial and ulnar arteries.
On the right side, the subclavian artery arises from the brachiocephalic trunk behind the right sternoclavicular articulation; on the left side, it springs from the arch of the aorta, behind the left common carotid. The branches of the subclavian artery are the vertebral artery (entering the skull through the foramen magnum, uniting with the vessel of the opposite side to form the basilar artery), the thyrocervical trunk, the internal thoracic artery (dividing at the level of the sixth intercostal space into the musculophrenic and superior epigastric arteries), the costocervical trunk, and the dorsal scapular artery.
The axillary artery is the continuation of the subclavian, which commences at the outer border of the first rib. The branches of these vessels are, from the first part, the highest thoracic; from the second part, the thoracoacromial and lateral thoracic; and from the third part, the subscapular, posterior humeral circumflex, and anterior humeral circumflex.
The brachial artery commences at the lower margin of the tendon of the teres major. Passing down the arm, it ends about 1 cm below the bend of the elbow, where it branches into the radial and ulnar arteries. At first, the brachial artery lies medial to the humerus, but as it runs down the arm, it gradually gets in front of the bone; at the bend of the elbow, it lies midway between its 2 epicondyles. The branches of this artery are the deep brachial (profunda brachii), the superior ulnar collateral, the nutrient, the inferior ulnar collateral, and the muscular branches.
The radial artery commences at the bifurcation of the brachial, just below the bend of the elbow, and passes along the radial side of the forearm to the wrist. The branches of the radial artery may be divided into 3 groups, corresponding with the 3 regions in which the vessel is situated: a forearm group (radial recurrent, muscular, palmar carpal, and superficial palmar), a wrist group (dorsal carpal and first dorsal metacarpal), and a hand group (princeps pollicis, radialis indicis, and deep palmar arch).
The ulnar artery is the larger of the 2 terminal branches of the brachial and begins a little below the bend of the elbow. The branches may be arranged in the following groups: a forearm group (anterior ulnar recurrent, posterior ulnar recurrent, common interosseous, and muscular), a wrist group (palmar carpal and dorsal carpal), and a hand group (superficial palmar arch and a contribution to the deep palmar arch).
Arteries of lower limbs
The artery that supplies the greater part of the lower extremity is the direct continuation of the external iliac. It runs as a single trunk from the inguinal ligament to the lower border of the popliteal fossa, where it divides into 2 branches, the anterior and posterior tibial arteries. The upper part of the main trunk is named the femoral artery, the lower part the popliteal artery.
The femoral artery begins immediately behind the inguinal ligament and ends at the junction of the middle and lower thirds of the thigh, where it passes through an opening in the adductor magnus to become the popliteal artery. In the upper third of the thigh, the femoral artery is contained in the femoral triangle (Scarpa's triangle); in the middle third of the thigh, it is contained in the adductor canal (Hunter’s canal). The branches of the femoral artery are the superficial epigastric (arising from the front of the femoral artery about 1 cm below the inguinal ligament), superficial iliac circumflex, superficial external pudendal, highest genicular, deep external pudendal, muscular, and profunda femoris arteries.
Profunda femoris artery
The profunda femoris is a large vessel arising from the lateral and back part of the femoral artery that gives off the following branches: lateral femoral circumflex, medial femoral circumflex, perforating, and muscular. The terminal part of the profunda is sometimes named the fourth perforating artery.
The popliteal artery is the continuation of the femoral and courses through the popliteal fossa. It extends from the opening in the adductor magnus and vertically downward to the lower border of the popliteus, where it divides into the anterior and posterior tibial arteries. The branches of the popliteal artery are the muscular, cutaneous, and geniculars. Around and above the patella and on the contiguous ends of the femur and tibia is an intricate network of vessels forming a superficial and a deep plexus.
Anterior tibial artery
The anterior tibial artery commences at the bifurcation of the popliteal, at the lower border of the popliteus. It becomes the dorsalis pedis artery at the level of the anterior aspect of the ankle, where it is most superficial. The branches of the anterior tibial artery are the posterior tibial recurrent, anterior tibial recurrent, anterior lateral malleolar, muscular, and anterior medial malleolar arteries.
The dorsalis pedis is the continuation of the anterior tibial. It passes forward from the ankle joint along the tibial side of the dorsum of the foot to the proximal part of the first intermetatarsal space, where it divides into 2 branches, the first dorsal metatarsal and the deep plantar.
Posterior tibial artery
The posterior tibial artery begins at the lower border of the popliteus. The branches are the fibular, posterior medial malleolar, nutrient, communicating, muscular, medial calcaneal, and lateral and medial plantar arteries.
The fibular artery arises from the posterior tibial artery and passes obliquely toward the fibula. It then runs behind the tibiofibular syndesmosis and divides into lateral calcaneal branches, which ramify on the lateral and posterior surfaces of the calcaneus.
The pulmonary trunk conveys the venous blood from the right ventricle of the heart to the lungs. It is a short, wide vessel, arising from the conus arteriosus of the right ventricle. The whole of this vessel is contained within the pericardium. It is enclosed with the ascending aorta in a single tube of the visceral layer of the serous pericardium, which is continued upward upon them from the base of the heart. On either side of its origin is the auricle of the corresponding atrium and a coronary artery, with the left coronary artery passing in the first part of its course behind the vessel.
The right branch of the pulmonary trunk, the right pulmonary artery, is longer and larger than the left and runs horizontally to the right, behind the ascending aorta and the superior vena cava and in front of the right bronchus within the root of the right lung, to the hilum, where it divides into 2 branches. The left branch of the pulmonary trunk, the left pulmonary artery, is shorter and somewhat smaller than the right and passes horizontally in front of the descending aorta and left bronchus within the root of the left lung to the hilum, where it divides into 2 branches, 1 for each lobe of the lung.
Arteries are composed of three coats: an internal or endothelial coat (tunica intima), a middle or muscular coat (tunica media), and an external or connective tissue coat (tunica adventitia). The 2 inner coats together are very easily separated from the external coat.
The arteries, in their distribution throughout the body, are included in thin fibroareolar investments, which form their sheaths. The vessel is loosely connected with its sheath by delicate areolar tissue, and the sheath usually encloses the accompanying veins, and sometimes a nerve.
All the larger arteries, like the other organs of the body, are supplied with blood vessels. These nutrient vessels, called the vasa vasorum, arise from a branch of the artery or from a neighboring vessel and are distributed to the external coat.  Arteries are also supplied with nerves, which are derived from the sympathetic nervous system. These nerves form intricate plexuses upon the surfaces of the larger trunks and run along the smaller arteries as single filaments. The branches derived from these plexuses penetrate the external coat and are distributed principally to the muscular tissue of the middle coat; by causing the contraction and relaxation of this tissue, these branches regulate the amount of blood sent to any part.
Atherosclerosis is a condition in which fatty material collects along the walls of medium and large arteries. This fatty material thickens, forms calcium deposits, and may eventually block the arteries. Pieces of plaque can break off and move through the affected artery to smaller blood vessels, blocking them and causing tissue damage or death (embolization). Blood clots can also form around a tear (fissure) in the plaque, leading to blocked blood flow.
Atherosclerosis can affect many different organ systems (eg, heart, lungs, brain, intestines, kidneys, and extremities), and it has been proposed as the primary etiology of descending thoracic and abdominal aortic aneurysms and the second most common cause of ascending aortic aneurysms. If the clot moves into an artery, it can cause a stroke or heart attack. Risk factors for atherosclerosis include diabetes, high blood pressure, smoking, high blood cholesterol levels, increasing age, high-fat diet, obesity, and personal or family history of heart disease.
An aortic aneurysm is a permanent localized dilation whose diameter is at least 1.5 times larger than the expected normal diameter of that artery. The diagnosis of an aneurysm in the thoracic or abdominal aorta requires knowledge of its normal diameter: at the level of the mid-descending thoracic aorta, the average aortic diameter is 28 mm for men and 26 mm for women; at the level of the celiac axis, it is 23 mm for men and 20 mm for women; and at the infrarenal aorta, it is 19.5 mm for men and 15.5 mm for women.
Aortic aneurysms are the 13th leading cause of mortality in the United States, and the mean age at the time of diagnosis ranges from 59 to 69 years. Men are typically diagnosed at a younger age, and a 2:1 to 4:1 male predominance exists. Traditional risk factors have included atherosclerosis, smoking, hypertension, and genetic disorders such as Marfan syndrome and Ehlers-Danlos syndrome. According to the law of Laplace, wall tension increases as the radius of an aneurysm increases (tension = pressure × radius). Therefore, it is intuitively apparent that larger aneurysms have a greater risk of rupture is intuitive, and for this reason, the ultimate disease process is the same for all: progressive aortic dilatation and eventual rupture.
Aortic aneurysms may be classified into 3 groups according to their location: ascending aorta, descending thoracic aorta (any portion of the aorta between the left subclavian artery and the diaphragm), or thoracoabdominal aorta (which may involve the entire thoracoabdominal aorta from the origin of the left subclavian artery to the aortic bifurcation) They are standardized according to the Crawford classification, which shows the extent of aortic involvement.
Although aortic aneurysms remain asymptomatic for long periods, most ultimately produce various symptoms before they rupture. When the aneurysm is large in the region of the aortic hiatus, pressure on adjacent structures may cause midback and epigastric pain. Other potential signs and symptoms related to compression or erosion of adjacent organs include stridor, wheezing, cough, hemoptysis, dysphagia, and gastrointestinal obstruction or bleeding. The pain (located in abdomen or back between scapulae) may be acute in onset, signifying impending rupture; in that case, the patient presents in extremis.
A significant number of aortic aneurysms are asymptomatic when diagnosed, being incidentally noted on chest radiography (the enlarged ascending aorta produces a convex contour of the right superior mediastinum) or another imaging study, such as echocardiography or computed tomography (CT). CT scanning provides precise evaluation of the aorta in regard to size, extent, and location of the disease process.
Once an aortic aneurysm has been discovered, precise determination of its extent and diameter is the next step toward determining the appropriate treatment and, when repair is indicated, planning the appropriate intervention. Because the diameter of an aneurysm strongly correlates with the risk of rupture or dissection, size has long been used as the criterion for elective surgical intervention. Emergent operation is indicated in the setting of a rupture aortic aneurysm. Open repair or endovascular treatment can be considered.
Aortic dissection is a potentially life-threatening condition in which a progressive separation of the aortic wall layers occurs, usually after a tear forms in the intima and inner media. Propagation of the separation within the layers of the media creates a new channel (the false lumen, in which blood remains still) that is separated from the original (the true lumen, in which blood continues to travel) by the dissecting membrane.
As the aortic dissection grows bigger, the channel with immotile blood can get bigger and push on other branches of the aorta. This usually occurs in the thoracic portion of the artery but may also occur in the abdominal portion. The acute form of aortic dissection is often rapidly lethal (50% of patients suffering acute type A aortic dissection are dead within 48 hours), whereas those surviving the initial event go on to develop a chronic dissection with more protean manifestations.
Aortic dissection occurs in approximately 2 out of every 10,000 people and is most often seen in men aged 40-70. It is classified as type A or B (Stanford classification), depending on where it begins and ends: type A begins in the first (ascending) part of the aorta, and type B begins in the descending part of the aorta. It may be also classified as type I, II, and III according to the De Bakey system: type I include dissections that involve the proximal aorta, arch, and descending thoracic aorta; type II only involves the ascending aorta; and type III include dissections that originate in the descending thoracic and thoracoabdominal aorta.
Several risk factors have been identified that can damage the aortic wall and lead to dissection, including atherosclerosis, high blood pressure, aging, bicuspid aortic valve, connective tissue disorders, and traumatic injury. Hypertension is the mechanical force most often associated with dissection and is associated in more than 75% of cases.
The symptoms usually begin abruptly. Pain may be described as sharp, stabbing, or tearing, and it is usually located in the midsternum for ascending aortic dissection and in the interscapular region for descending thoracic aortic dissection. The pain changes position and typically moves to the arms and legs as the dissection worsens (migratory pain). Patients may also present with signs or symptoms related to malperfusion of the brain (involvement of the brachiocephalic vessels), limbs, or visceral organs. Chronic aortic dissection is usually asymptomatic, and presenting patients often experience intermittent dull chest pain or even severe skeletal pain from erosion into the bony thorax with large or rapidly expanding aneurysms.
Diagnostic imaging--CT or echocardiography (transthoracic or transesophageal)--is essential to clarify the anatomy of an aortic dissection. CT scanning is widely available and is now the most frequently used test to diagnose acute aortic dissection. It requires an intravenous (IV) contrast medium and can be performed quickly.
Hospitalization is mandatory, and drugs that lower blood pressure must be given through a vein (IV). Strong pain relievers are usually needed, and heart medications such as beta-blockers may reduce some of the symptoms. Furthermore, type A aortic dissections require immediate surgery to repair the aorta, whereas type B aortic dissections may be treated with medication first. If the aortic valve is damaged, valve replacement is necessary. If the heart arteries are involved, a coronary bypass is also performed.