Acetabulum

This article is about the human anatomical region. For the Ancient Roman vessel, see Acetabulum (cup). For the unit of measure, see Acetabulum (unit).

Bone: Acetabulum of pelvis
Pelvic girdle
The Acetabulum
Latin	Acetabulum
Gray's	subject #57 237
MeSH	Acetabulum

The acetabulum (pron.: /æsɨˈtæbjʊləm/) is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.

Structure

There are three bones of the os coxae (hip bone) that come together to form the acetabulum. Contributing a little more than two-fifths of the structure is the ischium, which provides lower and side boundaries to the acetabulum. The ilium forms the upper boundary, providing a little less than two-fifths of the structure of the acetabulum. The rest is formed by the pubis, near the midline.

It is bounded by a prominent uneven rim, which is thick and strong above, and serves for the attachment of the acetabular labrum, which reduces its opening, and deepens the surface for formation of the hip joint. At the lower part of the acetabulum is the acetabular notch, which is continuous with a circular depression, the acetabular fossa, at the bottom of the cavity of the acetabulum. The rest of the acetabulum is formed by a curved, crescent-moon shaped surface, the lunate surface, where the joint is made with the head of the femur. Its counterpart in the pectoral girdle is the glenoid fossa.

The acetabulum is also home to the acetabular notch, an attachment site for the ligamentum teres, a triangular, somewhat flattened band implanted by its apex into the antero-superior part of the fovea capitis femoris. The notch is converted into a foramen by the transverse acetabular ligament; through the foramen nutrient vessels and nerves enter the joint. This is what holds the head of the femur securely in the acetabulum.

The well-fitting surfaces of the femoral head and acetabulum, which face each other, are lined with a layer of cartilage, lubricated by a thin film of fluid. Friction inside a normal hip is less than one-tenth that of ice gliding on ice^{[citation needed]}.

Circulation

The acetabular branch of the obturator artery supplies the acetabulum through the acetabular notch. The pubic branches supply the pelvic surface of the acetabulum. Deep branches of the superior gluteal artery supply the superior region and the inferior gluteal artery supplies the postero-inferior region.

Etymology

Main article: Acetabulum (cup)

The word acetabulum literally means "little vinegar cup". It was the Latin word for a small vessel for serving vinegar. The word was later also used as a unit of volume, equal to roughly 270 ml.

Perforate Acetabulum

An example of a perforated acetabulum on an ornithischian dinosaur.

In reptiles and in birds, the acetabula are deep sockets. Organisms in the dinosauria clade are defined by a perforate acetabulum, a hip socket with a hole at the center of its inside surface.

Additional images

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  Right hip bone. External surface.

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  Plan of ossification of the hip bone.

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  Symphysis pubis exposed by a coronal section.

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  Left hip-joint, opened by removing the floor of the acetabulum from within the pelvis.

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  Hip-joint, front view.

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  Capsule of hip-joint (distended). Posterior aspect.

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  Structures surrounding right hip-joint.

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  Acetabulum

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  Hip joint. Lateral view. Acetabulum

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  Hip joint. Lateral view. Acetabulum

References

• "Acetabular Labral Tears". Retrieved 20 November 2012. 
• "A study of the Arterial Supply of the Human Acetabulum using a Corrosion Casting Method". US National Library of Medicene. Retrieved 20 November 2012. 
• "Ligament of Head of Femur". Wikipedia. 

External links

• SUNY Labs 17:01-0501 - "Major Joints of the Lower Extremity: Hip joint"
• SUNY Labs 43:os-0407 - "The Female Pelvis: Articulated bones of pelvis"

This article incorporates text from a public domain edition of Gray's Anatomy.