ABSTRACT
The tibial nerve enters the tarsal tunnel and divides into a medial and a plantar nerve. They accompany their vascular supply separated only by a thin membrane (see Figures 50.1 to 50.3). The innervation of the plantar medial nerve on the planta pedis can be compared with the innervation of the median nerve in the hand (see Figure 50.4). Having passed the medial (upper) canal of lacuna vasonervorum of the tarsal tunnel, the nerve lies behind the vessels situated above the abductor hallucis muscle. The nerve crosses below the talus and the navicular bone. Then, the nerve crosses the lateral margin of the abductor hallucis muscle lying between the fibromuscular part of the muscle and the navicular tuberosity (i.e., the nerve is lying within the osteofibro-muscular tunnel, where it can often be compressed). The medial plantar nerve follows the medial margin of the flexor digitorum brevis muscle under the flexor hallucis longus tendon and the flexor digitorum longus muscle. At the level of the metatarsal bones, the nerve branches into the digital plantar communis nerves (Figure 51.1). Before its ramification, the nerve provides cutaneous branches to the medial part of the planta pedis and muscular branches to the abductor hallucis muscle, the flexor digitorum brevis muscle, the medial head of the flexor pollicis brevis muscle, and to the two medial lumbrical muscles. The digital plantar communis nerves branch at the base of the toes into the digital plantar proprii nerves, which supply the plantar side of the first, second, third and medial side of the fourth toe.
