The obturator foramen
is the hole created by the ischium
bones of the pelvis
through which nerves and muscles pass.
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 by a ligamentous band, a specialized part of the obturator membrane, attached to two tubercles:
Through the canal the obturator vessels and obturator nerve pass out of the pelvis.
For etymology see obturate and foramen.
Reflecting the overall gender differences between male and female pelvises, the obturator foramina are round in the male and oval 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.
- - "Major Joints of the Lower Extremity: hip and sacrum (anterior view)"
- - "Pelvis & Perineum: Male Urethrogram"
- Photo at vc.cc.tx.us