Ligament of head of femur

The ligament of the head of the femur, also known as the ligamentum capitis femoris or the ligamentum teres femoris, is a triangular, somewhat flattened band implanted by its apex into the antero-superior part of the fovea capitis femoris; 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 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.

It has, however, but little influence as a ligament past childhood according to some references. According to the Encyclopedia Britannica, the ligament gives the femur a stabilizing strength which, as in the orangatan, some animals lack.