| Acetabulum of pelvis | |
|---|---|
 Pelvic girdle | |
.jpg) A model of the acetabulum (cotyloid cavity) | |
| Details | |
| Identifiers | |
| Latin | acetabulum |
| MeSH | D000077 |
| TA98 | A02.5.01.002 |
| TA2 | 1308 |
| FMA | 16579 |
| Anatomical terms of bone | |
Theacetabulum (/ˌæsɪˈtæbjələm/;[1]pl.:acetabula), also called thecotyloid cavity, is aconcave surface of thepelvis. Thehead of the femur meets with the pelvis at the acetabulum, forming thehip joint.[2][3]
There are three bones of theos coxae (hip bone) that come together to form theacetabulum. Contributing a little more than two-fifths of the structure is theischium, which provides lower and side boundaries to the acetabulum. Theilium forms the upper boundary, providing a little less than two-fifths of the structure of the acetabulum. The rest is formed by thepubis, near the midline.
It is bounded by a prominent uneven rim, thick and strong on top, which serves as the point of attachment for theacetabular labrum. The acetabular labrum reduces the size of the opening of the acetabulum and deepens the surface of the hip joint. At the lower part of the acetabulum is theacetabular notch, which is continuous with a circular depression, the acetabularfossa, at the bottom of the cavity of the acetabulum. The rest of the acetabulum is formed by a curved, crescent-moon shaped surface, thelunate surface, where the joint is made with thehead of the femur. Its counterpart in the pectoral girdle is theglenoid fossa.[4]
The acetabulum is also home to the acetabular fossa, an attachment site for theligamentum teres, a triangular, somewhat flattened band implanted by its apex into the antero-superior part of thefovea 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.[2]
The well-fitting surfaces of the femoral head and acetabulum, which face each other, are lined with a layer of slippery tissue calledarticular cartilage, which is lubricated by a thin film ofsynovial fluid. Friction inside a normal hip is less than one-tenth that of ice gliding on ice.[5][6]
The acetabular branch of the obturator artery supplies theacetabulum through the acetabular notch. The pubic branches supply the pelvic surface of theacetabulum. Deep branches of the superior gluteal artery supply the superior region and the inferior gluteal artery supplies the postero-inferior region.[7]
Inreptiles andbirds, theacetabula are deep sockets. Organisms in thedinosauria clade are defined by a perforateacetabulum, which can be thought of as a "hip-socket". The perforateacetabulum is a cup-shaped opening on each side of the pelvic girdle formed where theischium,ilium, andpubis all meet, and into which the head of the femur inserts.[8][9] The orientation and position of theacetabulum is one of the main morphological traits that caused dinosaurs to walk in an upright posture with their legs directly underneath their bodies. In a relatively small number of dinosaurs, particularlyankylosaurians (e.g.Texasetes pleurohalio), an imperforateacetabulum is present, which is not an opening, but instead resembles a shallow concave depression on each side of the pelvic girdle.
In infants and children, a Y-shapedepiphyseal plate called thetriradiate cartilage joins the ilium, ischium, and pubis. This cartilageossifies as the child grows.[10]
The wordacetabulum literally means "little vinegar cup". It was theLatin word for a small vessel for servingvinegar. The word was later also used as aunit of volume.
This article incorporates text in thepublic domain frompage 237 of the 20th edition ofGray's Anatomy(1918)
