Fourth toe flexion sign: a new clinical sign for identification of the superficial peroneal nerve.

We describe a clinical sign for identification of the superficial peroneal nerve. Flexion of the fourth toe accentuates the subcutaneous course of the cutaneous branches of the superficial peroneal nerve. Thirty feet from 15 volunteers were examined for presence of this sign. Twenty-six of 30 feet had a positive sign that was confirmed by infiltrating the observed nerve with 1% lignocaine and correlating the consequent area of hypoaesthesia with the known distribution of the superficial peroneal nerve.