Anatomy
The left side of the heart pumps oxygen-rich blood to the rest of the body. Blood leaving the left ventricle passes through the aorta, the largest artery in the body. The aorta passes down through the chest, where it is called the thoracic aorta, and continues into the abdomen, where it is called the abdominal aorta.
In the lower abdomen, at about the level of the fourth lumbar vertebra, the aorta splits into two smaller arteries called the common iliac arteries. Each common iliac artery splits again into the external iliac artery and the internal iliac artery. Each internal iliac artery has many branches which supply the deep organs and other structures of the pelvis.
Each external iliac artery courses downward and laterally along the border of the psoas muscles. Once they pass below the inguinal ligaments (paired ligaments which extend obliquely across the groin), they become the femoral arteries, which supply each leg. Along their course, each external iliac artery gives off several small branches to the neighboring psoas muscle and two large branches: the inferior epigastric artery and the deep iliac circumflex artery.
The inferior epigastric artery arises just above the inguinal ligament and supplies blood to the anterior abdominal wall. The deep iliac circumflex artery also arises just above the inguinal ligament and helps supply the iliacus muscle and the deep and lateral abdominal wall.
Function
The external iliac artery is the chief source of blood supply to the legs. Its branches also supply blood to the lower abdominal wall.
An artery is a blood vessel that carries blood away from the heart, while a vein is generally a blood vessel which carries blood back toward the heart. Usually, blood in arteries is rich in oxygen and blood in veins is low in oxygen, though there are exceptions. Walls of arteries are typically thicker and more muscular than those of veins, so as to better contend with the pulsatile, high-pressure blood coming from the heart.
Clinical Significance
The external iliac artery can be affected by atherosclerosis. Sometimes called “hardening of the arteries,” atherosclerosis is a disease of the large arteries characterized by the accumulation of fats and fibrous tissue (scar) in vessel walls. Atherosclerosis can cause narrowing, occlusion, or abnormal dilatation of affected vessels; when it affects the arteries of the brain or heart, it is the primary cause of heart disease and stroke.
Atherosclerosis can cause narrowing or even blockage of the external iliac arteries. Patients may have no symptoms, have pain on exertion (claudication), or have critical limb ischemia. Treatment depends on your specific symptoms as well as what coexisting diseases are present. Treatment may focus on medical therapy (such as blood pressure reduction and cholesterol-reducing medications) to prevent progression of disease. Quitting smoking is important. More severe cases may require placement of a stent or creation of a surgical bypass.
Disease of the walls of a large artery can cause loss of mechanical integrity and ballooning of a vessel segment, called an aneurysm. The most common site of true aneurysm is the abdominal aorta. The iliac arteries can be affected as well, and iliac artery aneurysms are often associated with aneurysms of the abdominal aorta. The most common site of iliac artery aneurysm is in the common iliac arteries, followed by the internal iliac arteries. External iliac arteries are less common sites.
When iliac artery aneurysms increase in size, they may cause symptoms such as compression of adjacent structures. Clots may develop in aneurysms that can obstruct the vessel or can break off and obstruct smaller arteries in the extremities. Large aneurysms are at risk for rupture (bursting).
Aneurysms that are large, rapidly expanding, or cause symptoms are usually treated. Treatment may take the form of stenting or open surgical repair and can be considered once the size of the aneurysm reaches 3.5 cm.
Elite, competitive athletes such as cyclists, runners, and speed skaters are at increased risk for a condition called external iliac artery endofibrosis. The exact cause of this condition is not known for sure, but it results in the deposition of scar tissue in the walls of the external iliac arteries, causing narrowing of the vessels. The disease may become severe and progress to total blockage of the arteries. Patients may develop cramping in their thighs or calves that occurs with strenuous activity. Treatment usually requires surgical repair or bypass, although stenting is also used.
The external iliac artery is also important if kidney transplantation is being considered. During kidney transplantation, the donated kidney is typically placed in the recipient’s pelvis, and the original (native) kidneys are left in place. Most commonly, the surgeon connects the new kidney to the recipient’s external iliac artery. If the external iliac artery or lower aorta is compromised by significant atherosclerosis, the surgical plan may have to be changed, and a more complex procedure required.
