neurologic disorders
Facial Nerve Palsy
Pathophysiology of Facial Nerve Palsy
The facial muscles are innervated peripherally (infranuclear innervation) by the ipsilateral 7th cranial nerve and centrally (supranuclear innervation) by the contralateral cerebral cortex. Central innervation tends to be bilateral for the upper face (eg, forehead muscles) and unilateral for the lower face. As a result, both central and peripheral lesions tend to paralyze the lower face. However, peripheral lesions (facial nerve palsy) tend to affect the upper face more than central lesions (eg, stroke) do. 