<prompt> A lesion involving upper motor neuron of facial nerve manifests asUpper half of the face is affected, lower half normalLeft half of the faceRight half of the faceUpper half of the face normal, lower half affected  <response>: The facial muscles are innervated by the facial nerve. Damage to the facial nerve in the internal acoustic meatus by a tumor, in the middle ear by infection or operation, in the facial nerve canal perineuritis, Bells palsy, or in the parotid gland by a tumor or caused by lacerations of the face will cause distoion of the face, with drooping of the lower eyelid, and the angle of the mouth will sag on the affected side. This is essentially a lower motor neuron lesion. Check voluntary movement of the upper pa of the face on the affected side: in supranuclear lesions such as a coical stroke upper motor neuron; above the facial nucleus in the pons, the upper third of the face is spared while the lower two thirds are paralyzed. The orbicularis, frontalis, and corrugator muscles are innervated bilaterally, which explains the pattern of facial paralysis in these cases 