The purpose of the examination of facial strength is to assess for lesions of the central or peripheral nervous system motor pathways that move the face.

All patients should have facial movements assessed as part of a complete neurologic examination. In most patients, the examination of facial symmetry and strength can be limited to observing the patient’s smile. For patients who present with a complaint of facial weakness or who show evidence of facial weakness on examination, a more detailed assessment to distinguish upper motor neuron from lower motor neuron weakness should be performed, as described in How to Examine Facial Strength.

The upper motor neuron pathway for facial movement begins in the motor cortex of each frontal lobe. Axons from these nerve cells travel downward as the corticospinal tract, which then synapse at the facial nerve nucleus in the pons. Axons from the facial nucleus—the lower motor neuron for facial movement—leave the pons as the facial nerve to innervate all of the muscles of facial expression on that side of the face. The part of the facial nerve nucleus that moves the lower part of the face (e.g., mouth movement) is innervated mainly by fibers from the contralateral corticospinal tract. The part of the facial nerve nucleus that moves the upper part of the face (e.g., forehead wrinkling and eye closure) is innervated by fibers from both the contralateral and the ipsilateral corticospinal tracts.

None.

Normally, there should be full and symmetric movements of the mouth, forehead, and eye closure.