The acetabulum is a large, hemispherical-shaped cavity on the lateral side of the hip bone. The hip joint is created when the head of the femur connects to the pelvis at the acetabulum. Here, let’s discuss the structure and function of the acetabulum.

Table of Contents

What Is Acetabulum?

The concave pelvic surface is known as the acetabulum or cotyloid cavity. The hip joint is created when the head of the femur connects to the pelvis at the acetabulum.

Ilium, ischium and pubis are the three components that make up each pelvic bone. At birth, these bones are joined by cartilage in the acetabulum region; later, between the ages of 16 and 18, they fuse together to form a single bone.

Acetabulum – Anatomy

The huge cup-shaped acetabulum for femoral head articulation is located on the lateral surface of the pelvic bone in the region where the ilium, ischium and pubis fuse. A layer of slick tissue known as articular cartilage, which is lubricated by a thin film of synovial fluid, lines the surfaces of the femoral head and acetabulum that are well-fitting to one another.

  • A noticeable notch on the inferior side of the acetabulum’s margin serves as its marking (acetabular notch).
  • The acetabulum’s wall is made up of articular and nonarticular components.
  1. The nonarticular component is rough and creates a tiny circular depression called the acetabular fossa in the acetabular floor’s inferior and central parts. The acetabular notch and fossa are one continuous structure.
  2. The articular surface is large and encompasses the acetabular fossa’s anterior, posterior and superior edges. The anterior, posterior and superior portions of the acetabulum have an articular surface that resembles a horseshoe, also known as a lunate surface. It articulates with the femur’s head to form the hip joint and is lined with hyaline cartilage.
  • Blood veins and nerves run through the acetabular notch, while the ligament of the femur’s head has an attachment point in the acetabular fossa.
  • The acetabulum’s rim is slightly elevated (the acetabular labrum) by means of a fibrocartilaginous collar. The labrum crosses the acetabular notch inferiorly, acting as the transverse acetabular ligament, transforming the notch into a foramen. Thus, it deepens the acetabular cavity.

Also Check: MCQs on Types of Joints

Acetabulum Functions

The hip joint is created by the articulation of the acetabulum and the femoral head. When these structures work together, we can easily run, walk and move freely. Similar to the shoulder girdle, the pelvic girdle places the hip in the right place for movement. The pelvis is not joined, whereas the shoulder girdle contains a variety of joints. The pelvis can still rotate in all three planes, though. The acetabular position is altered by pelvic rotation so that it is pointed in the direction of the following femoral movement.

The acetabulum is obliquely inclined toward the front. An acetabulum that is misaligned does not adequately protect the femoral head, which can lead to early onset osteoarthritis and chronic dislocation.

This was a brief note on the acetabulum. For more NEET-related content, visit BYJU’S.

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Frequently Asked Questions


What is acetabulum?

The three bones that make up the hip come together to form the cup-shaped socket called the acetabulum. The hip joint is created when the head of the femur bone fits into the acetabular socket.

Describe the hip joint.

The hip joint is a synovial articulation made by the acetabulum of the pelvic bone and the head of the femur. The femoral head forms the ball of the hip joint, and the acetabulum forms the socket.

Describe the femoral head.

The head of the femur, or femoral head, is the highest point of the femur (thigh none). It is a globular structure supported by the flattened femoral neck.

What is an acetabular notch?

A deep notch in the hip bone’s acetabulum is termed the acetabular notch. The circular nonarticular depression known as the acetabular fossa, which is located at the bottom of the acetabular cavity, is continuous with the acetabular notch.

What is acetabular labrum?

A fibrocartilaginous lip that surrounds and deepens the acetabulum is called the acetabular labrum. It offers the acetabulum an articulating surface, enabling the femur’s head to articulate with the pelvis.


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