Fig. 1. Pathways for the supranuclear control of facial movement. The upper part of the face is supplied from both hemispheres. Also shown is postulated motor input to the ipsilateral orbicularis oris muscle from the hypoglossal nucleus, a possible explanation for the facial weakness seen in lesions of the lower brain stem. (Haymaker W: Bing's Local Diagnosis in Neurological Diseases, 15th ed, p 230. St. Louis, CV Mosby, 1969)