The obturator foramen (Latin foramen obturatum) is the large opening created by the
ischium and
pubis bones of the
pelvis through which nerves and blood vessels pass.
Structure
It is bounded by a thin, uneven margin, to which a strong membrane is attached, and presents, superiorly, a deep groove, the obturator groove, which runs from the pelvis obliquely medialward and downward.
This groove is converted into the
obturator canal
The obturator canal is a passageway formed in the obturator foramen by part of the obturator membrane and the pelvis. It connects the pelvis to the thigh.
Structure
The obturator canal is formed between the obturator membrane and the pelvis. Th ...
by a ligamentous band, a specialized part of the
obturator membrane
The obturator membrane is a thin fibrous sheet, which almost completely closes the obturator foramen.
Its fibers are arranged in interlacing bundles mainly transverse in direction; the uppermost bundle is attached to the obturator tubercles and ...
, attached to two tubercles:
* one, the posterior obturator tubercle, on the medial border of the ischium, just in front of the
acetabular notch
The acetabular notch is a deep notch in the acetabulum of the hip bone. The acetabular notch is continuous with a circular non-articular depression, the acetabular fossa, at the bottom of the cavity: this depression is perforated by numerous aper ...
* the other, the anterior obturator tubercle, on the
obturator crest of the
superior ramus of the
pubis
Variation
Reflecting the overall
sex differences between male and female pelvises, the obturator foramina are oval in the male and wider and more triangular in the female.
Additionally, unilateral pelvis
hypoplasia can cause differences in size between the obturator foramina, and there are even rare reports of individual pelvises featuring a double obturator foramen in one of the hip bones.
Function
Through the canal the
obturator artery
The obturator artery is a branch of the internal iliac artery that passes antero-inferiorly (forwards and downwards) on the lateral wall of the pelvis, to the upper part of the obturator foramen, and, escaping from the pelvic cavity through the ob ...
,
obturator vein
The obturator vein begins in the upper portion of the adductor region of the thigh and enters the pelvis through the upper part of the obturator foramen, in the obturator canal.
It runs backward and upward on the lateral wall of the pelvis below ...
and
obturator nerve pass out of the pelvis.
See also
*
Obturator internus muscle
The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis.
It exits the pelvic cavity through the lesser sciatic foramen.
The ...
*
Obturator externus muscle
The external obturator muscle, 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 sometimes c ...
Additional images
Pelvic girdle illustration.svg, The two circles at the bottom are the obturator foramina.
Gray541.png, Variations in origin and course of obturator artery.
Gray547.png, The relations of the femoral and abdominal inguinal rings, seen from within the abdomen. Right side.
Slide3ADA.JPG, Anterior view of the body pelvis
References
External links
* - "Major Joints of the Lower Extremity: hip and sacrum (anterior view)"
* - "Pelvis & Perineum: Male Urethrogram"
Photo at vc.cc.tx.us
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Bones of the pelvis