The abdominal aorta bifurcates at the level of the fourth lumbar vertebra to form the two common iliac arteries, each of which further branches into the external and the internal iliac artery. Bodytomy provides a labeled iliac artery diagram to help you understand the anatomy and function of the common iliac.
Did You Know?
There’s an inverse relationship between the length of the common iliac and the internal iliac arteries. If the common iliac artery is short, the internal iliac artery will be long, and if the internal iliac is short, the common iliac will be longer. In case of an anatomical variation where the common iliac arteries are absent, the external and internal iliac arteries will arise together from the distal end of the aorta.
Aorta, which is the largest artery of the human body that originates from the left ventricle of the heart, is divided into the ascending aorta, aortic arch, and the descending aorta (which is divided into thoracic aorta and abdominal aorta). It carries blood from the left ventricle to the coronary arteries. The ascending aorta performs the function of supplying blood to the head, neck, and the arms, whereas the thoracic aorta supplies blood to the organs located in the chest cavity. The abdominal aorta supplies blood to the liver, pancreas, stomach, spleen, kidneys, intestines, reproductive glands, etc.
At the fourth lumbar vertebra, the abdominal aorta branches into the common iliac arteries. Being a paired structure, the common iliac artery and its branches are present on the right, as well as the left side. The common iliac arteries could be as short as 1.2 cm or as long as 11 cm. However, the length usually varies between 3.7 to 7.5 cm. The branches of the common iliac are involved in supplying blood to the organs in the pelvic region.
Common Iliac Artery Location and Function
The right and the left common iliac arteries are the terminal branches of the aorta that travel down and bifurcate into two branches on each side at the pelvic inlet, between the last lumbar vertebrae and the sacrum. The common iliac arteries give off small branches to the psoas major, peritoneum, extraperitoneal connective tissue, ureters, etc. Occasionally, it may give off branches to the iliolumbar and accessory renal arteries. However, it is basically the terminal branches of the common iliac arteries that play a major role in blood supply to the pelvis and the lower limbs. The right common iliac artery divides into the right internal and external iliac arteries. Similarly, the left common iliac artery divides into the left internal and external arteries. While the internal iliac artery supplies the wall and the organs of the pelvic cavity, the external iliac artery splits into various branches that supply blood to the legs.
Internal Iliac Artery
The internal iliac artery, which is also referred to as the hypogastric artery, is mainly responsible for the blood supply to the pelvic region. Its anterior division is divided into the visceral branches that supply blood to the external genitalia and the organs in the pelvic cavity. On the other hand, the posterior division divides into the parietal branches, which are involved in supplying blood to the pelvic wall and gluteal muscles. The anterior division is longer than the posterior division.
The branches of the anterior division include:
- Superior vesical artery (supplies vas deferens in males)
- Obliterated umbilical artery (continuation of superior vesical)
- Inferior vesical artery
The aforementioned branches supply blood to the bladder.
Its three visceral branches include:
- Middle rectal artery
- Uterine artery in females
- Vaginal artery in females (corresponds to the inferior vesical artery in males)
It has three parietal branches that include:
- Obturator artery
- Internal pudendal artery (terminal branch)
- Inferior gluteal artery (terminal branch)
The posterior division of the internal iliac artery has three parietal branches. These include:
- Iliolumbar artery
- Lateral sacral artery
- Superior gluteal artery
The iliolumbar artery passes upwards out of the pelvis in front of the lumbosacral trunk. It supplies blood to the psoas and quadratus lumborum. It also gives off a spinal branch into the foramen between the fifth lumbar vertebra and the sacrum. Its iliac branch supplies blood to the iliacus muscle and the iliac bone. The lateral sacral artery gives off a superior and inferior branch. Its inferior branch travels in front of the sacral ventral rami. Running laterally to the anterior sacral foramina, which is located in front of the roots of the sacral plexus, the lateral sacral artery supplies blood to the roots and piriformis in the pelvic region. The superior gluteal artery passes between the lumbosacral trunk and the ventral ramus of S1. It supplies blood to the greater sciatic foramen, which is located above the upper border of piriformis.
The superior and inferior vesical arteries supply blood to the bladder, whereas the middle rectal artery supplies blood to the muscular wall of the rectum. The superior vesical artery is also responsible for the blood supply to the adjacent ureter and vas deferens. The inferior vesical artery, provides blood to the lower section of the bladder, ureter, vas deferens, seminal vesicle, as well as prostate. The umbilical artery gives rise to the artery to the ductus deferens in men.
The uterine artery runs above the ureter and extends upwards at the cervix. It provides blood to the uterine tube and joins the tubal branch of the ovarian artery. The vaginal artery, which might be a branch of the uterine artery, provides blood to the upper part of the vagina.
A small branch of the obturator artery provides blood to the periosteum of the back of the pubis. The obturator artery supplies blood to the obturator canal. It also joins with the pubic branch of the inferior epigastric artery. The inferior gluteal artery exits the pelvic region through the greater sciatic foramen and runs to the buttock. In front of the inferior gluteal artery lies the internal pudendal artery, which exits the pelvis through the greater sciatic foramen.
The left and the right external iliac arteries are responsible for supplying blood to the lower limbs. Its branches include:
- Inferior epigastric artery
- Deep iliac circumflex artery
- Femoral artery
Running inferior to the inguinal ligament, the external iliac artery becomes the femoral artery, which is responsible for supplying blood to the thighs. Arising right above the external iliac, the inferior epigastric artery joins the superior epigastric artery. The deep iliac circumflex artery arises from the side of the external iliac. At the anterior superior iliac spine, it joins a branch of the lateral femoral circumflex artery. The deep iliac circumflex artery mainly supplies blood to the anterior iliac crest bone flap.
On a concluding note, the common iliac artery and its branches are essential for the blood supply to the pelvic region and the legs. Running along the common iliac arteries are the common iliac veins, which lie at the back, and to the right of these arteries. The common iliac veins also bifurcate into the external and internal iliac veins. These are also paired, which means that they are present on the left, as well as the right. Both internal and external iliac veins join to form the common iliac veins, which drain deoxygenated blood from the pelvic region and the lower limbs to inferior vena cava.