What is the retinaculum?

The retinaculum is a band or band-like structure that serves to hold tendons in place as they pass over joints. It can be found in various locations throughout the body, including the wrist, ankle, and knee.

In the wrist, there are two retinacula: the extensor retinaculum and the flexor retinaculum. The extensor retinaculum is a thick band of connective tissue located on the back of the hand, which holds the tendons of the extensor muscles in place as they pass over the wrist joint. The flexor retinaculum, also known as the transverse carpal ligament, is a broad band of fibrous tissue located on the front of the wrist. It holds the tendons of the flexor muscles in place and forms the roof of the carpal tunnel.

In the ankle, there are also two retinacula: the superior extensor retinaculum and the inferior extensor retinaculum. These structures help to hold the tendons of the ankle muscles in place as they pass over the ankle joint.

In the knee, the retinaculum is a thickening of the joint capsule on either side of the patella (kneecap). The lateral retinaculum and medial retinaculum help to keep the patella in its proper alignment during knee movements.

Overall, the retinaculum plays a crucial role in maintaining the stability and proper function of tendons as they cross over joints.