The obturator artery [a.obturatoria], when derived from the internal iliac, usually arises from the anterior division of that vessel, but not infrequently from its posterior division. The artery is directed forwards through the pelvis to reach the groove on the under surface of the horizontal portion of the pubes, at the upper part of the thyroid foramen. Beneath this bone it passes out of the pelvis, and immediately divides into its terminal branches. In its course through the pelvis the artery is placed between the pelvic fascia and the peritoneum, a little below the obturator nerve. Beneath the pubes it lies with the nerve in an oblique canal, formed partly by the groove in the bone, and partly by fibrous tissue.
Whilst within the pelvis, besides others of smaller size, the obturator artery often supplies a branch to the iliac fossa and muscle, and one which runs backwards upon the urinary bladder.
As it is about to enter the canal by which it escapes from the pelvis, it usually gives off one or more small anastomotic vessels, which ramify on the back of the pubes, and communicate behind that bone and behind the attachments of the abdominal muscles to its horizontal ramus, with small offsets from the epigastric artery. These anastomosing branches lie to the inner side of the femoral ring.
Having passed out of the pelvis through the canal beneath the horizontal ramus of the pubes, the obturator artery divides immediately into an external and an internal branch, which are deeply placed among the muscles at the upper part of the front of the thigh. '
The internal branch curves inwards beneath the external obturator muscle, close to the inner margin of the thyroid foramen, and furnishes branches to the obturator muscles, the gracilis, and the adductor muscles.
The external branch has a similar arrangement near the outer margin of the thyroid foramen, descends as far as the tuberosity of the ischium, and supplies the obturator muscles and the upper ends of the long muscles which are attached to the tuberosity. This branch usually sends off a small artery, which enters the hip-joint through the cotyloid notch, and ramifies along the round ligament as far as the head of the femur.
The two foregoing branches of the obturator artery communicate with each other near the lower margin of the obturator ligament, and anastomose with branches of the internal circumflex artery. Besides this, the external branch communicates with offsets from the sciatic artery near the tuberosity of the ischium.