ABSTRACT
The facial muscles are supplied by the VIIth cranial nerve, which arises from the facial nucleus in the pons. The facial nerve is accompanied, for part of its course, by the chorda tympani, which innervates the taste receptors of the anterior two-thirds of the tongue. The muscles of the forehead are represented in the ipsilateral, as well as the contralateral, cerebral hemisphere. Stroke is the most common cause of an upper motor neurone facial palsy, and Bell’s1 palsy the most common cause of a lower motor neurone palsy. Other causes of facial palsy are rare. The site of the lesion causing facial palsy is assessed by noting: the pattern of facial weakness and the presence of other signs. The patient is unable to raise the right eyebrow (frontalis) or screw up the right eye (orbicularis oculi), or smile on the right, or purse his lips on the right (orbicularis oris) or contract the right platysma.
