The posterior tibiofibular ligament is a fibrous band of connective tissue that travels horizontally over the rear surface of the tibiofibular syndesmosis, which is a meeting area of the fibula (calf bone) and the tibia (shinbone) that is composed of the interosseus membrane and both the interosseous and anterior ligaments.
One of the primary functions of the tibiofibular ligament is to make up the back 'wall' area of the recipient socket for the talar trochlea of the ankle. The trochlea is a fibrous structure that is shaped similarly to a pulley.
The posterior tibiofibular ligament is part of the lateral malleolus, which is one of the fibula bone's sharp and bony lower extremities near the ankles. It is significantly smaller in size than the lateral malleolus' anterior ligament, which is flat and triangular in shape. Another common name for the ligament is the posterior inferior ligament.