ABSTRACT
The anterior tarsal tunnel lies under a thickening of the dorsal pedis fascia and above the talus bone. These fascial thickenings form a retinaculum that fixes and redirects the extensor tendons. While at times consisting of four branches in a cruciform shape, the inferior extensor retinaculum typically has three branches that form a Y transversely across the foot’s dorsum. The base of the Y, the lateral portion, originates in the sinus tarsi on the lateral side of the calcaneus. As it passes over the tendons for the extensor digitorum longus, the retinaculum divides into two rami: the superior ramus, which inserts on the medial malleolus, and the inferior ramus, which inserts on the dorsal surface of the navicular and first cuneiform bones. Occasionally, a superfluous second lateral branch may exist, which inserts on the lateral malleolus, producing a retinaculum with a cruciform shape, the ligamentum cruciforme. Medially and below the superior and inferior rami, the tendons and the tendon sheaths of the anterior tibialis and extensor hallucis longus muscles run accompanied by the dorsal pedis artery and vein. The deep peroneal nerve joins these structures in the anterior tarsal tunnel after innervating all the foot extensors, except for the extensor digitorum brevis muscle, which is the only muscle affected by anterior tarsal tunnel compression. Within the tunnel, the nerve divides into a lateral and a medial branch (Figure 49.1).
