Head of femur

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Anatomy and function of the thigh bone.

The head of femur, often called the femoral head, forms the round, spherical-shaped proximal end of the femur, which is the longest bone in the body and located in the thigh.

It is covered with hyaline articular cartilage except for a small, medially placed depression posteroinferior to its center known as the fovea. This non-articular depression serves as the attachment point for a small ligament, known as the ligament of head of femur (ligamentum capitis femoris), that connects the head of femur to the acetabulum.

The head of femur is positioned anterosuperiorly and medially. It articulates with the acetabulum on the lateral surface of the hip bone to form the hip joint, and is enclosed within the joint capsule.

The blood supply to the head of the femur is provided by an arterial ring around the femoral neck, located just outside the attachment point of the fibrous joint capsule. This ring is formed by the medial and lateral circumflex femoral arteries. Ascending cervical branches, also known as retinacular arteries, arise from this ring and ascend along the neck to supply the head. Additionally, the artery of ligamentum teres, also referred to as the artery to the head of femur, makes a minor contribution to the blood supply.

Disruption of the retinacular arteries, which constitute the primary blood supply, for instance, following a femoral neck fracture, can lead to the death of bone tissue in the head of the femur due to inadequate blood flow. This condition is known as avascular necrosis.