If the common peroneal nerve is damaged, which action still retains complete function?

If the common peroneal nerve is damaged, the action that still retains complete function is inversion. This is because the muscles responsible for inversion of the foot, primarily the tibialis anterior and the tibialis posterior, are innervated by different nerves. The tibialis anterior is innervated by the deep peroneal nerve, while the tibialis posterior is innervated by the tibial nerve.

In contrast, dorsiflexion and eversion involve muscles that are affected by the common peroneal nerve. For example, dorsiflexion relies on the function of the tibialis anterior, which would be compromised if the common peroneal nerve is damaged. Similarly, eversion is primarily facilitated by the peroneus longus and peroneus brevis, both of which are innervated by branches of the common peroneal nerve.

Extension of the digits, related to movements of the toes, is also affected due to its dependence on the function of the extensor digitorum longus and other associated muscles that receive their nerve supply from the common peroneal nerve.

Therefore, the action of inversion remains functional despite damage to the common peroneal nerve because the necessary muscle innervation comes from different