Ligament of head of femur

Ligament of head of femur
Left hip-joint, opened by removing the floor of the acetabulum from within the pelvis (Ligament of head of femur labeled as ligt. teres at cente.)
Hip-joint, front view. The capsular ligament has been largely removed (ligament visible at center labeled as ligam teres)
Details
From	Femur head
To	Acetabular notch
Identifiers
Latin	Ligamentum capitis femoris, ligamentum teres femoris
TA	A03.6.07.010
FMA	43235
Anatomical terminology []

In human anatomy, the ligament of the head of the femur (round ligament of the femur or the foveal ligament) is a ligament located in the hip. It is triangular in shape and somewhat flattened. The ligament is implanted by its apex into the antero-superior part of the fovea capitis femoris and its base is attached by two bands, one into either side of the acetabular notch, and between these bony attachments it blends with the transverse ligament.

It is ensheathed by the synovial membrane, and varies greatly in strength in different subjects; occasionally only the synovial fold exists, and in rare cases even this is absent.

The ligament of the head of the femur contains within it the acetabular branch of the obturator artery.

The ligament is made tense when the thigh is semiflexed and the limb then abducted or rotated outward; it is, on the other hand, relaxed when the limb is adducted.

Research suggests it contributes little influence as a ligament past childhood, although it may still be important in transmitting arterial supply to the femoral head.

In humans, it has been suggested that it is not the ligamentum teres but the hip capsule (specifically the iliofemoral, ischiofemoral and pubofemoral ligaments) that provides the primary resistance to dislocation in the extended hip. However, recent research has suggested the ligamentum teres of the femur may have a number of functions, including a significant biomechanical role on the basis of cadaveric studies where increases of range of motion were seen after sectioning of the ligament.

It has been suggested that some animals, such as the orangutan and Indian elephant lack a ligamentum teres. However, the presence of a ligamenum teres, albeit with a morphology different to the human version, has been found upon dissection in both these animals. In the orangutan it is believed to play a significant role in preventing dislocation of the femoral head in extreme ranges of motion. In the Indian elephant it is the primary support of the hip joint when the hind limbs are abducted.