inferior extensor retinaculum of foot inferior extensor retinaculum of foot the inferior extensor retinaculum of the foot (cruciate crural ligament, lower part of anterior annular ligament) is a y-shaped band placed in front of the ankle-joint, the stem of the y being attached laterally to the upper surface of the calcaneus, in front of the depression for the interosseous talocalcaneal ligament; it is directed medialward as a double layer, one lamina passing in front of, and the other behind, the tendons of the peroneus tertius and extensor digitorum longus.