| Obturator foramen | |
|---|---|
 Symphysis pubis exposed by a coronal section. Obturator canal labelled at center. | |
| Details | |
| Identifiers | |
| Latin | foramen obturatum |
| TA98 | A02.5.01.008 |
| TA2 | 1314 |
| FMA | 16999 |
| Anatomical terms of bone | |
The obturator foramen is the large,[ citation needed ] bilaterally paired opening of the bony pelvis. It is formed by the pubis and ischium. It is mostly closed by the obturator membrane except for a small opening, the obturator canal, through which the obturator nerve and vessels pass.
The obturator foramen is situated inferior and somewhat anterior to the acetabulum. It is bounded by the pubis bone and the ischium: superiorly by the (grooved obturator surface) of the superior ramus of pubis, inferiorly by the ramus of ischium, and laterally by (the anterior edge of) the body of ischium (including by the margin of the acetabulum). [1]
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]
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]
The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis.
Articles related to anatomy include:
The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis.
In vertebrate anatomy, the hip, or coxa in medical terminology, refers to either an anatomical region or a joint on the outer (lateral) side of the pelvis.
The external obturator muscle or obturator externus muscle is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis.
The adductor magnus is a large triangular muscle, situated on the medial side of the thigh.
The lumbar plexus is a web of nerves in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve. Additionally, the ventral rami of the fourth lumbar nerve pass communicating branches, the lumbosacral trunk, to the sacral plexus. The nerves of the lumbar plexus pass in front of the hip joint and mainly support the anterior part of the thigh.
The ischium forms the lower and back region of the hip bone.
In vertebrates, the pubis or pubic bone forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing of the three bones that make up the hip bone. The left and right pubic bones are each made up of three sections; a superior ramus, an inferior ramus, and a body.
The sacrotuberous ligament is situated at the lower and back part of the pelvis. It is flat, and triangular in form; narrower in the middle than at the ends.
The inferior gluteal artery is a terminal branch of the anterior trunk of the internal iliac artery. It exits the pelvis through the greater sciatic foramen. It is distributed chiefly to the buttock and the back of the thigh.
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 an anterior branch and a posterior branch.
The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet. Its lower boundary is the pelvic floor.
The pubic tubercle is a prominent tubercle on the superior ramus of the pubis bone of the pelvis.
The obturator membrane is a thin fibrous sheet, which almost completely closes the obturator foramen.
The nerve to obturator internus is a mixed nerve providing motor innervation to the obturator internus muscle and gemellus superior muscle, and sensory innervation to the hip joint. It is a branch of the sacral plexus. It is one of the group of deep gluteal nerves.
The pelvic fasciae are the fascia of the pelvis and can be divided into:
The following outline is provided as an overview of and topical guide to human anatomy:
The hip bone is a large flat bone, constricted in the center and expanded above and below. In some vertebrates it is composed of three parts: the ilium, ischium, and the pubis.
The pelvis is the lower part of an anatomical trunk, between the abdomen and the thighs, together with its embedded skeleton.
This article incorporates text in the public domain from page 237 of the 20th edition of Gray's Anatomy (1918)
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