(upper motor neuron facial weakness) Results in weakness of muscles of facial expression contralateral to the lesion with sparing of the forehead. Thus patients with supranuclear facial weakness can raise both their eyebrows because motoneurons to forehead are bilaterally innervated by the corticobulbar tract whereas motoneurons to the rest of the facial muscles are innervated only by the contralateral cortex. Contrast with Bell's Palsy.