Common Iliac Arteries

1. Overview

The common iliac arteries are major blood vessels in the abdomen that are responsible for supplying oxygenated blood to the lower part of the body, including the pelvis, legs, and organs in the lower abdomen. They arise from the bifurcation of the abdominal aorta, typically at the level of the fourth lumbar vertebra. The common iliac arteries then divide into two main branches: the internal iliac arteries, which supply blood to the pelvic organs, and the external iliac arteries, which continue into the legs. The common iliac arteries play a critical role in ensuring that the lower body receives the necessary oxygen and nutrients for normal function.

2. Location

The common iliac arteries are located in the lower abdomen and pelvis. They originate from the bifurcation (splitting) of the abdominal aorta, which occurs at the level of the fourth lumbar vertebra (L4). From this point, each common iliac artery travels laterally toward the pelvis, running along the sides of the vertebral column. At the level of the sacroiliac joint, each common iliac artery bifurcates into two main branches:

• Internal iliac artery: This artery supplies blood to the pelvis, including the reproductive organs, bladder, and gluteal muscles.

• External iliac artery: This artery continues into the lower limbs, becoming the femoral artery, which supplies blood to the legs.

The common iliac arteries are located on either side of the body, and their bifurcation marks the division between the abdominal and pelvic circulatory systems.

3. Structure

The common iliac arteries are large, muscular arteries that have structural features designed to handle high-pressure blood flow from the heart. Some of their key structural features include:

• Origin: The common iliac arteries originate from the bifurcation of the abdominal aorta, which occurs at the level of the L4 vertebra. Each common iliac artery travels toward the pelvis and then bifurcates into the internal and external iliac arteries.

• Diameter and Length: The common iliac arteries typically have a diameter of around 1 to 1.5 cm in adults, though this can vary. They are approximately 5 to 7 cm in length, depending on the individual's anatomy.

• Wall Composition: Like other arteries, the common iliac arteries have three distinct layers:

  • Intima: The innermost layer, composed of endothelial cells, which provides a smooth surface for blood flow.

  • Media: The middle layer, consisting of smooth muscle and elastic tissue, which enables the artery to expand and contract with each heartbeat.

  • Adventitia: The outer layer, made of connective tissue, which provides structural support and helps anchor the arteries to surrounding tissues.

• Branching: The common iliac arteries give rise to two important branches:

  • Internal iliac artery: Supplies blood to the pelvic organs, such as the bladder, uterus, prostate, rectum, and gluteal muscles.

  • External iliac artery: Continues down into the legs, where it becomes the femoral artery, which supplies blood to the lower limbs.

4. Function

The primary function of the common iliac arteries is to supply oxygenated blood to the lower part of the body, including the pelvis, reproductive organs, and lower extremities. Some key functions of the common iliac arteries include:

• Blood supply to the pelvis: The internal iliac artery, a branch of the common iliac artery, supplies blood to the pelvic organs, including the bladder, reproductive organs, rectum, and gluteal muscles. These organs require a continuous supply of oxygen and nutrients for normal function.

• Blood supply to the legs: The external iliac artery, another branch of the common iliac artery, continues into the lower extremities, where it becomes the femoral artery. The femoral artery supplies blood to the legs, including the muscles and tissues of the thighs, knees, and lower legs.

• Facilitating venous return: The common iliac arteries, by supplying oxygenated blood to the lower body, also facilitate venous return from the lower extremities. They help maintain the balance of blood circulation in the lower limbs and pelvis, preventing venous stasis and supporting efficient blood flow back to the heart.

5. Physiological Role(s)

The common iliac arteries have several key physiological roles that contribute to the proper functioning of the lower body. These include:

• Oxygen and nutrient delivery to the lower body: The common iliac arteries ensure that the lower limbs and pelvic organs receive an adequate supply of oxygenated blood, which is essential for cellular function, muscle contraction, and the maintenance of tissues.

• Support of lower body movement: By supplying blood to the muscles of the legs and pelvis, the common iliac arteries enable the lower limbs to perform movements such as walking, running, and lifting. These activities require a continuous supply of oxygenated blood to sustain muscle function and endurance.

• Support of pelvic function: The internal iliac artery, a branch of the common iliac artery, supplies blood to the pelvic organs, including the bladder, reproductive organs, and rectum. These organs rely on a consistent blood supply for normal function, particularly during activities like urination, digestion, and reproduction.

• Adaptation during physical activity: During exercise or physical exertion, the body’s demand for oxygen and nutrients increases. The common iliac arteries help meet these demands by ensuring that more oxygenated blood is delivered to the muscles of the lower body, enabling them to function optimally during physical activity.

6. Clinical Significance

The common iliac arteries are clinically significant because they supply blood to the lower body. Dysfunction or blockage in these arteries can lead to serious conditions, including ischemia (lack of blood flow) in the lower limbs and pelvic organs. Some key clinical conditions associated with the common iliac arteries include:

• Atherosclerosis: Atherosclerosis is the buildup of fatty deposits (plaques) in the arteries, which can lead to narrowing and hardening of the arteries. When atherosclerosis affects the common iliac arteries, it can restrict blood flow to the pelvis and lower extremities, leading to symptoms such as pain, weakness, and reduced mobility. Severe cases can lead to peripheral artery disease (PAD) or even limb ischemia. Treatment options include lifestyle changes, medications, and surgical procedures such as angioplasty or bypass surgery.

• Common iliac artery aneurysm: An aneurysm is a localized dilation or bulging of the artery, which can occur in the common iliac arteries. This condition is often caused by atherosclerosis or high blood pressure. If left untreated, an aneurysm can rupture, leading to severe internal bleeding. Surgical intervention is often required to repair the aneurysm.

• Peripheral artery disease (PAD): PAD occurs when the arteries supplying blood to the legs become narrowed or blocked. This condition can affect the common iliac arteries and lead to symptoms such as leg pain, cramping, and difficulty walking. PAD can be managed with lifestyle changes, medications, or surgical interventions like angioplasty or bypass surgery to restore blood flow.

• Carotid and iliac artery dissection: A dissection occurs when there is a tear in the wall of the artery, allowing blood to flow between the layers of the vessel wall. This can lead to reduced blood flow or even stroke-like symptoms. Dissections in the common iliac arteries can be caused by trauma or underlying conditions like fibromuscular dysplasia. Treatment may involve blood thinners, surgery, or endovascular procedures.

• Embolism: An embolism occurs when a clot or other material travels through the bloodstream and becomes lodged in a blood vessel, blocking blood flow. When an embolism occurs in the common iliac arteries, it can lead to ischemia and damage to the tissues of the lower limbs. Treatment may include anticoagulants or surgical removal of the embolus.

The common iliac arteries play a critical role in delivering oxygenated blood to the lower body. Any dysfunction or blockage in these arteries can lead to serious complications, including ischemia, aneurysms, or even limb loss. Early detection, diagnosis, and treatment are essential for preventing severe cardiovascular events and maintaining optimal circulatory function in the lower body.