Variations in the Pattern of Muscle Innervation by the L5 and S1 Nerve Roots

Evidence based on electrical studies is presented for the standard and anomalous patterns of innervation of muscles supplied by the fifth lumbar and first sacral nerve roots. Although considerable controversy still exists, previous work in this field suggests that the L5 nerve root supplies tibialis anterior, extensor hallucis longus, extensor digitorum brevis, and the lateral head of gastrocnemius, while the S1 nerve root innervates the medial...