Obturator foramen

The margin of the foramen is thin and uneven, and gives attachment to the obturator membrane. Superiorly, it presents a deep groove - the obturator groove - which passes obliquely inferomedially from the pelvis.^[citation needed]

The foramen is largely closed by the obturator membrane save for a small opening at the superolateral end of the obturator foramen - the obturator canal - which establishes a communication between the pelvic cavity and the thigh. This canal gives passage to the obturator nerve, artery, and veins.^[1]

The free edge of the obturator membrane that bounds the obturator canal attaches at two tubercles (which may be indistinct):^[1]

• The anterior obturator tubercle - situated on the obturator crest^{[citation needed]} at the anterior extremity of the inferior border of the superior ramus of pubis.^[1]

• The posterior obturator tubercle - situated at the anterior border of the acetabular notch^[1] (and thus on the medial border of the ischium^{[citation needed]}).

Variation

In accordance with the overall sex dimorphism of the pelvis,^{[citation needed]} the obturator foramina are oval in the male, and wider and rather triangular in the female.^[1]

Unilateral pelvic hypoplasia can cause differences in size between the obturator foramina. Rarely, the obturator foramen may be doubled on one side.^[2]

See also

• Obturator internus muscle
• Obturator externus muscle

Additional images

• 
  The two circles at the bottom are the obturator foramina.
• 
  Variations in origin and course of obturator artery
• 
  The relations of the femoral and abdominal inguinal rings, seen from within the abdomen. Right side.
• 
  Anterior view of the body pelvis

References

This article incorporates text in the public domain from page 237 of the 20th edition of Gray's Anatomy (1918)