Internal Iliac Arteries

1. Overview

The internal iliac arteries are major blood vessels that supply blood to the pelvis, reproductive organs, and gluteal regions. They are branches of the common iliac arteries, which themselves arise from the abdominal aorta. The internal iliac arteries provide oxygenated blood to a number of vital structures, including the pelvic organs, the muscles of the gluteal region, and parts of the lower limbs. The internal iliac arteries play an essential role in maintaining blood flow to both the pelvic organs and the lower extremities. They give rise to several important branches that serve various organs, and in many surgical and clinical situations, these arteries are a focal point for managing vascular health in the pelvic region.

2. Location

The internal iliac arteries are located in the pelvic cavity. They arise from the common iliac arteries, which bifurcate from the abdominal aorta at the level of the L4 vertebra. The common iliac arteries split into the internal and external iliac arteries at the sacroiliac joint. The internal iliac arteries are located deep within the pelvis, running inferiorly and medially. They pass behind the peritoneum and give off numerous branches that supply the pelvic organs, gluteal muscles, and parts of the lower limbs. The internal iliac arteries typically do not cross midline but lie on each side of the body, corresponding to the left and right pelvic regions.

3. Structure

The internal iliac arteries are large vessels with a complex structure designed to meet the needs of the pelvic and lower limb circulatory system. Some key structural characteristics of the internal iliac arteries include:

• Origin: The internal iliac arteries originate from the common iliac arteries at the level of the sacroiliac joints, which is near the L4 vertebra. The common iliac arteries bifurcate into the internal and external iliac arteries, with the internal iliac arteries being the smaller branches.

• Course: The internal iliac arteries descend into the pelvis, running posteriorly to the peritoneum and anterior to the sacrum. They travel towards the pelvic viscera and are located at the bifurcation of the common iliac arteries.

• Diameter: The internal iliac arteries are relatively large, with diameters ranging from 5 to 7 millimeters in adults, although their size can vary depending on individual factors such as age, gender, and vascular health.

• Branching Pattern: The internal iliac arteries give off numerous branches that supply blood to the pelvic organs, gluteal muscles, and the perineum. These branches can be categorized into anterior and posterior divisions:

  • Anterior division: Supplies blood to the pelvic viscera, such as the bladder, rectum, uterus, vagina, and part of the lower limbs.

  • Posterior division: Supplies blood to the posterior abdominal wall, gluteal muscles, and muscles of the lower back.

4. Function

The primary function of the internal iliac arteries is to provide oxygenated blood to the pelvic organs, gluteal muscles, and perineum. The branches of the internal iliac arteries ensure that vital structures in the lower abdomen and pelvis receive the necessary nutrients and oxygen for proper function. Some of the main functions of the internal iliac arteries include:

• Blood supply to pelvic organs: The internal iliac arteries supply oxygenated blood to a variety of pelvic organs, including the bladder, rectum, uterus, vagina, and prostate. These organs require constant blood flow to carry out their functions, such as urination, reproduction, and defecation.

• Blood supply to the gluteal muscles: The internal iliac arteries provide blood to the muscles of the gluteal region, including the gluteus maximus, gluteus medius, and gluteus minimus. These muscles are responsible for hip movement and stability, particularly during walking, running, and sitting.

• Supply to the perineum: The internal iliac arteries supply blood to the perineum, which includes the external genitalia and the muscles involved in sexual function and childbirth. These branches are essential for maintaining sexual and reproductive health.

• Facilitating lower limb circulation: Some branches of the internal iliac arteries, such as the obturator and inferior gluteal arteries, provide blood to the muscles of the thighs, hip joints, and buttocks. This is important for maintaining the health of the lower extremities, particularly during physical activity.

5. Physiological Role(s)

The internal iliac arteries perform several key physiological roles that are essential for the function of the pelvic organs, lower extremities, and other systems:

• Oxygenation and nutrient delivery: The internal iliac arteries deliver oxygenated blood to a variety of pelvic organs, including the reproductive organs, bladder, and rectum. These organs rely on constant blood flow for normal function, particularly during activities such as urination, digestion, and reproduction.

• Support of muscular function: By supplying blood to the gluteal muscles and muscles of the pelvic floor, the internal iliac arteries play a role in the movement and stability of the lower body. Proper circulation to these muscles is essential for mobility, balance, and posture.

• Facilitation of reproduction: The internal iliac arteries supply the uterus, vagina, and other reproductive organs, ensuring that they receive the necessary blood flow for menstruation, pregnancy, and childbirth. The role of these arteries is vital for both male and female reproductive health.

• Regulation of blood pressure: The internal iliac arteries, as part of the overall circulatory system, help regulate blood pressure within the pelvis and lower body. By maintaining proper blood flow to the organs and muscles of the lower body, the internal iliac arteries help ensure that adequate oxygen and nutrients are delivered to tissues, while also preventing congestion or venous pooling.

6. Clinical Significance

The internal iliac arteries are clinically significant due to their crucial role in supplying blood to the pelvic organs, gluteal muscles, and lower extremities. Any disruption or blockage in these arteries can lead to serious health complications. Some key clinical conditions associated with the internal iliac arteries include:

• Atherosclerosis and Peripheral Artery Disease (PAD): Atherosclerosis can cause narrowing and hardening of the internal iliac arteries, reducing blood flow to the pelvic organs and lower limbs. This can result in symptoms such as pain, claudication, or even tissue death in severe cases. Treatment may involve lifestyle changes, medications, or surgical interventions such as angioplasty or bypass surgery.

• Internal Iliac Artery Aneurysm: An aneurysm is a dilation or ballooning of the artery wall. Aneurysms of the internal iliac artery can lead to rupture, causing life-threatening internal bleeding. Early detection through imaging techniques, such as ultrasound or CT scan, is crucial. Treatment may involve surgical repair or endovascular procedures to prevent rupture.

• Pelvic Congestion Syndrome: Pelvic congestion syndrome occurs when there is chronic venous insufficiency in the pelvic veins, which are often affected by problems with the internal iliac arteries. This condition is more common in women and can lead to pelvic pain, especially during menstruation or sexual activity. Treatment may include medications, pelvic vein embolization, or surgery.

• Obturator Artery Variants: The obturator artery is a branch of the internal iliac artery that supplies the hip joint and muscles of the thigh. In some individuals, this artery may arise from a different source or have an unusual branching pattern, which can increase the risk of complications during surgeries involving the pelvis or hip joint.

• Endometriosis: Endometriosis, a condition where tissue similar to the uterine lining grows outside the uterus, can cause inflammation and scarring in the pelvic region, potentially affecting the internal iliac arteries. This can lead to chronic pelvic pain, and in severe cases, the arteries may become compressed, impairing circulation to the organs.

• Obstetric Complications: During childbirth, particularly in cases of pelvic trauma or cesarean section, damage to the internal iliac arteries can result in significant hemorrhage. Surgical intervention may be required to control bleeding and restore blood flow to the pelvic organs.

The internal iliac arteries are crucial for supplying oxygenated blood to the pelvic organs and lower extremities. Disorders such as atherosclerosis, aneurysms, pelvic congestion syndrome, and other vascular issues can significantly affect the function of these arteries and may lead to serious complications. Early diagnosis, appropriate management, and preventive measures are essential for maintaining vascular health in the pelvic region and preventing long-term complications.