What is a characteristic of the S1 nerve root?

The S1 nerve root is primarily associated with the common peroneal nerve, which has a significant role in foot eversion and plantarflexion. This nerve innervates the muscles responsible for lifting the outer edge of the foot, allowing for movements such as eversion. The action of foot eversion involves the peroneus longus and peroneus brevis muscles, both of which are innervated by the S1 nerve root.

In contrast, hip flexion is predominantly controlled by the lumbar plexus and involves primarily the L2 and L3 nerve roots, which innervate the iliopsoas muscle. Knee extension is mainly governed by the L3 and L4 nerve roots, which control the quadriceps muscle. Hip adduction is associated with the obturator nerve, primarily originating from the L2-L4 nerve roots. This highlights the distinct functions of each nerve root and their associated muscle actions, clearly establishing foot eversion as a characteristic movement of the S1 nerve root.