Acetabulum

Acetabulum

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Encyclopedia
The acetabulum is a concave surface 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:...

. The head of the femur
Femur head
The femur head is the highest part of the thigh bone . It is supported by the neck of the femur.The head is globular and forms rather more than a hemisphere, is directed upward, medialward, and a little forward, the greater part of its convexity being above and in front.Its surface is smooth,...

 meets with the pelvis at the acetabulum, forming the hip
Hip (anatomy)
In vertebrate anatomy, hip refer to either an anatomical region or a joint.The hip region is located lateral to the gluteal region , inferior to the iliac crest, and overlying the greater trochanter of the femur, or "thigh bone"...

 joint
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...

.

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
Ilium (bone)
The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...

 forms the upper boundary, providing a little less than two-fifths of the structure of the acetabulum. The rest is formed by the pubis
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....

, 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
Acetabular notch
The 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....

, 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
Lunate
Lunate is a term meaning crescent or moon-shaped. In the specialized terminology of lithic reduction, a lunate flake is a small, crescent-shaped flake removed from a stone tool during the process of pressure flaking....

 surface, where the joint is made with the head of the femur
Femur head
The femur head is the highest part of the thigh bone . It is supported by the neck of the femur.The head is globular and forms rather more than a hemisphere, is directed upward, medialward, and a little forward, the greater part of its convexity being above and in front.Its surface is smooth,...

. Its counterpart in the pectoral girdle is the glenoid fossa
Glenoid fossa
Glenoid fossa can refer to:* Glenoid cavity * Mandibular fossa...

.

In reptiles and in birds, the acetabula are deep sockets.

Etymology


The word acetabulum means "little vinegar cup", and was the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 word for a small vessel for storing vinegar
Vinegar
Vinegar is a liquid substance consisting mainly of acetic acid and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. Commercial vinegar is produced either by fast or slow fermentation processes. Slow methods generally are used with traditional...

 (see acetabulum
Acetabulum (cup)
In ancient dining, an acetabulum was a vinegar-cup, which, from the fondness of the Greeks and Romans for vinegar, was probably always placed on the table at meals to dip the food in before eating it. The vessel was wide and open above; and the name was also given to all cups resembling it in size...

). The word was later also used as a unit of volume, equal to roughly 270 ml
1 E-4 m³
To help compare different orders of magnitude, this page lists volumes between 10−4 m³ and 10−3 m³ or 100 millilitres and 1 litre. See also volumes or capacities of other orders of magnitude...

.

External links


- "Major Joints of the Lower Extremity: Hip joint" - "The Female Pelvis: Articulated bones of pelvis"