Obturator Foramen

What Is A Obturator Foramen?

The Obturator Foramen is a large, egg-shaped opening located at the front of the pelvis. It is formed out of the ischium and pubis bone allowing blood vessels and nerves to go through.

Obturator Foramen explained
Obturator Foramen – Contributed Illustration by Beckie Palmer

Medical Definition Of Obturator Foramen

It is covered by a thin fibrous membrane called the obturator membrane, which covers the inner and outer surfaces of the internal and external obturator muscles.

Its superior edge, which is missing from the membrane, forms the ‘obturator canal’ that allows the obturator nerves, arteries, and veins to leave the pelvis and enter the medial compartment of the thigh.

The foramen itself is bound by thin, uneven edges, to which a strong membrane is attached, and has a deep groove (the obturator groove) that runs through the pelvis medially and downwards.

This groove converts the canal into a band, which is a special part of this membrane attached to two tubercles:

  • the posterior obturator tubercle at the medial edge of the ischium, before the acetabular notch
  • the anterior obturator tubercle between the obturator crest and the superior ramus of the pubis

The obturator foramina reflect the general gender differences between the male and female pelvis and are oval in men and wide and triangular in women.

Unilateral pelvic hypoplasia caused by differences in the size of the obturator foramen is rare but has been reported in individuals whose pelvis has a double obturator foramen (one above and one below the hip bone).

 Anatomy of pubic area and obturator foramen
Anatomy of pubic area and obturator foramen

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