Obturator Foramen

Obturator Foramen – What Is It?

Obturator Foramen Location

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 location
Obturator Foramen – Contributed Illustration by Beckie Palmer

Obturator Foramen Definition

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

Obturator Foramen definition
Anatomy of pubic area and obturator foramen

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