The obturator artery is a branch of the

internal iliac artery The internal iliac artery (formerly known as the hypogastric artery) is the main artery of the pelvis. Structure The internal iliac artery supplies the walls and viscera of the pelvis, the buttock, the reproductive organs, and the medial com ...

that passes antero-inferiorly (forwards and downwards) on the lateral wall of the

pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

, to the upper part of the

obturator foramen The obturator foramen is the large, Bilateral symmetry, bilaterally paired opening of the bony pelvis. It is formed by the pubis and ischium. It is mostly closed by the obturator membrane except for a small opening, the obturator canal, through wh ...

, and, escaping from the pelvic cavity through the obturator canal, it divides into an anterior branch and a posterior branch.

Structure

In the pelvic cavity this vessel is in relation, laterally, with the obturator fascia; medially, with the

ureter The ureters are tubes composed of smooth muscle that transport urine from the kidneys to the urinary bladder. In an adult human, the ureters typically measure 20 to 30 centimeters in length and about 3 to 4 millimeters in diameter. They are lin ...

, ductus deferens, and

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesotheli ...

; while a little below it is the obturator nerve. The obturator artery usually arises from the

. Inside the pelvis the obturator artery gives off iliac branches to the

iliac fossa The iliac fossa is a large, smooth, concave surface on the internal surface of the Ilium (bone), ilium (part of the three fused bones making the hip bone). Structure The iliac fossa is bounded above by the iliac crest, and below by the Arcuate ...

, which supply the bone and the

Iliacus The iliacus is a flat, triangular muscle which fills the iliac fossa. It forms the lateral portion of iliopsoas, providing flexion of the thigh and lower limb at the acetabulofemoral joint. Structure The iliacus arises from the iliac fossa on t ...

, and anastomose with the ilio-lumbar artery; a vesical branch, which runs backward to supply the

bladder The bladder () is a hollow organ in humans and other vertebrates that stores urine from the kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the bladder is a distens ...

; and a pubic branch, which is given off from the vessel just before it leaves the

pelvic cavity The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet (the superior opening of the pelvis). Its lower boundary is the pelvic floor. The pelvic cavity primarily contains the reproduc ...

. The pubic branch ascends upon the back of the pubis, communicating with the corresponding vessel of the opposite side, and with the

inferior epigastric artery In human anatomy, the inferior epigastric artery is an artery that arises from the external iliac artery. It is accompanied by the inferior epigastric vein; inferiorly, these two inferior epigastric vessels together travel within the lateral um ...

. After passing through the obturator canal and outside of the pelvis, the obturator artery divides at the upper margin of the

, into an anterior branch and a posterior branch of the obturator artery which encircle the foramen under cover of the

obturator externus The external obturator muscle or obturator externus muscle (; OE) is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis. It is sometimes considered part of the medial compartment of thigh, and sometime ...

Anterior branch

The anterior branch of the obturator artery is a small

artery An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

in the thigh and runs forward on the outer surface of the obturator membrane and then curves downward along the anterior margin of the

. It distributes branches to the

pectineus The pectineus muscle (, from the Latin word ''pecten'', meaning comb) is a flat, quadrangular muscle, situated at the anterior (front) part of the upper and medial (inner) aspect of the thigh. The pectineus muscle is the most anterior adductor o ...

, adductors, and

gracilis muscle The gracilis muscle (; Latin for "slender") is the most superficial muscle on the medial side of the thigh. It is thin and flattened, broad above, narrow and tapering below. Structure It arises by a thin aponeurosis from the anterior margins ...

, and

anastomoses An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf#Veins, leaf veins, or streams. Such a connection may be ...

with the posterior branch and with the medial femoral circumflex artery.

Posterior branch

The posterior branch of the obturator artery is a small artery in the

thigh In anatomy, the thigh is the area between the hip (pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of bone tissu ...

and follows the posterior margin of the foramen and turns forward on the

inferior ramus of the ischium The ischium (; : is ...

, where it anastomoses with the anterior branch. It gives twigs to the muscles attached to the

ischial tuberosity The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones, or as a pair the sitting bones, is a large posterior bony protuberance on the superior ramus of the ischium. It ...

and anastomoses with the

inferior gluteal artery The inferior gluteal artery (sciatic artery) is a terminal branch of the anterior trunk of the internal iliac artery. It exits the pelvis through the greater sciatic foramen. It is distributed chiefly to the buttock and the back of the thigh. Ana ...

. It also supplies an articular branch which enters the hip-joint through the

acetabular notch The acetabular notch is a deep notch in the inferior portion of the rim of the acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur mee ...

, ramifies in the fat at the bottom of the

acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur meets with the pelvis at the acetabulum, forming the Hip#Articulation, hip joint. Structure The ...

and sends a twig along the ligament of head of femur (ligamentum teres) to the head of the femur. The blood supply to the femoral head and neck is enhanced by the artery of the ligamentum teres derived from the obturator artery. In adults, this is small and doesn't have much importance, but in children whose epiphyseal line is still made of cartilage (which doesn't allow blood supply through it), it helps to supply the head and neck of the femur on its own. The articular branch is usually patent until roughly 15 years of age. In adults it does not provide enough blood supply to prevent avascular necrosis in upper femur fractures.

Variation

The obturator artery usually arises from the main stem or from the anterior trunk of the

. It may arise from the

superior gluteal artery The superior gluteal artery is the terminal branch of the posterior division of the internal iliac artery. It exits the pelvis through the greater sciatic foramen before splitting into a superficial branch and a deep branch. Structure Origin Th ...

, and occasionally it arises from the external iliac. In about two out of every seven cases it arises from the inferior epigastric and descends almost vertically to the upper part of the

. In studies, it has been found that corona mortis is in half of all hemipelvis with a prevalence of 46%. In other studies, it is found to be 33.33% in both hemipelves of the individuals. The variation has also been found to be more common in patients from Europe than in Asia where studies have been conducted. In comparative studies, it was found that European patients had a 10% higher chance of having the arterial variation when compared to Asian population. The artery in this course usually lies in contact with the external iliac vein, and on the lateral side of the

femoral ring The femoral ring is the opening at the proximal, abdominal end of the femoral canal, and represents the (superiorly directed/oriented) base of the conically-shaped femoral canal. The femoral ring is oval-shaped, with its long diameter being direc ...

''(Figure A on diagram).'' It can also pass medial to the femoral ring along the margin of the lacunar ligament ''(Figure B).'' In either case it would be at risk of injury during the operation to repair a

femoral hernia Femoral hernias are hernias which occur just below the inguinal ligament, when abdominal contents pass through a naturally occurring weakness in the abdominal wall called the femoral canal. Femoral hernias are a relatively uncommon type, acco ...

, whether the hernia is reducible, incarcerated or strangulated. When the obturator artery travels along the lacunar ligament, it nearly encircles the femoral ring and can be lacerated during a femoral hernia repair. Most femoral hernias are repaired through a small (1/2 to 3/4 inch) incision in the groin area, rather than through the abdomen, so if a laceration were to occur, bleeding may not be immediately recognized and result in significant blood loss into the peritoneal cavity. Because of this danger, the anatomic variant in Figure B is sometimes referred to as the "crown of death" (corona mortis).

Additional images

File:Gray236.png, Right hip bone. Internal surface. File:Gray404.png, Left levator ani from within.

References

External links

* - "The Female Pelvis: Branches of Internal Iliac Artery" * () *
Variations at anatomyatlases.org

Variations at anatomyatlases.org
{{Authority control Arteries of the abdomen