The last muscle to demonstrate evidence of reinnervation during recovery for a radial nerve palsy is the extensor indicis proprius.
Abrams et al dissected 20 cadavers to identify the motor branches of the radial nerve. They determined the innervation order from proximal to distal was brachioradialis, extensor carpi radialis longus, supinator, extensor carpi radialis brevis, extensor digitorum communis, extensor carpi ulnaris, extensor digiti quinti, abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis, and extensor indicis proprius (Illustration A).
The Lateral Plantar Nerve ( n. plantaris lateralis; external plantar nerve ) supplies the skin of the fifth toe and lateral half of the fourth, as well as most of the deep muscles, its distribution being similar to that of the ulnar nerve in the hand. It passes obliquely forward with the lateral plantar artery to the lateral side of the foot, lying between the Flexor digitorum brevis and Quadratus plantæ and, in the interval between the former muscle and the Abductor digiti quinti, divides into a superficial and a deep branch. Before its division, it supplies the Quadratus plantæ and Abductor digiti quinti.
The sinus tarsi, or talocalcaneal sulcus, is an anatomic space bound by the calcaneus, talus, talocalcaneonavicular joint, and posterior facet of the subtalar joint. Pain from this location is usually felt in the lateral calcaneus and ankle, and is worse immediately following exercise and when walking on an uneven surface. 24 It can arise from repeated lateral ankle sprains or from repeated hyperpronation of the foot. 24 Initial treatment includes managing the underlying causes with orthotics or physical therapy, although anti-inflammatory or analgesic medications and corticosteroid injections ( Figure 6 ) may also be beneficial.