Facial, trigeminal, and hypoglossal motoneuron involvement was quantified in 25 amyotrophic lateral sclerosis patients and in normal controls. Measures included (1) maximum voluntary contraction of the lower lip, mandible, and tongue using custom-designed force transducers, (2) clinical functions of each muscle group, and in some patients (3) orofacial mobility using videofluoroscopy. All measures indicated that the tongue muscles were most severely affected, even in patients who initially had symptoms in the extremities.