Obturator foramen
Encyclopedia
The obturator foramen is the hole created by the ischium and pubis
bones of the pelvis
through which nerves and muscles pass.
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 artery
, obturator vein and obturator nerve
pass out of the pelvis.
--->
For etymology see obturate
.
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.
Pubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
bones of the pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
through which nerves and muscles pass.
General 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
Obturator canal
The obturator canal is a passageway formed in the obturator foramen by part of the obturator membrane. It connects the pelvis to the thigh.The obturator artery, obturator vein, and obturator nerve all travel through the canal.-Pathology:...
by a ligamentous band, a specialized part of the obturator membrane
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 completes the obturator canal for the passage of the...
, attached to two tubercles:
- one, the posterior obturator tubercle, on the medial border of the ischium, just in front of the acetabular notchAcetabular notchThe acetabulum presents below a deep notch, the acetabular notch, which is continuous with a circular non-articular depression, the acetabular fossa, at the bottom of the cavity: this depression is perforated by numerous apertures, and lodges a mass of fat....
- the other, the anterior obturator tubercle, on the obturator crestObturator crestThe anterior border of superior pubic ramus presents a sharp margin, the obturator crest, which forms part of the circumference of the obturator foramen superiorly and affords attachment to the obturator membrane....
of the superior ramusSuperior pubic ramusThe superior pubic ramus is a part of the pubic bone which forms a portion of the obturator foramen.It extends from the body to the median plane where it articulates with its fellow of the opposite side...
of the pubisPubis (bone)In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
Through the canal the obturator artery
Obturator artery
The obturator artery is a branch of the internal iliac artery that passes antero-inferiorly on the lateral wall of the pelvis, to the upper part of the obturator foramen, and, escaping from the pelvic cavity through the obturator canal, it divides into both an anterior and a posterior...
, obturator vein and obturator nerve
Obturator nerve
The obturator nerve in human anatomy arises from the ventral divisions of the second, third, and fourth lumbar nerves; the branch from the third is the largest, while that from the second is often very small.-Path:...
pass out of the pelvis.
--->
For etymology see obturate
Obturate
Obturate means to block or obstruct. With reference to firearms and airguns, obturation refers to the process of a bullet or pellet, made of soft material and often with a concave base, flaring under the pressure of firing to seal the bore and engage the barrel's rifling...
.
Variations
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
Hypoplasia
Hypoplasia is underdevelopment or incomplete development of a tissue or organ. Although the term is not always used precisely, it properly refers to an inadequate or below-normal number of cells. Hypoplasia is similar to aplasia, but less severe. It is technically not the opposite of hyperplasia...
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.