Cranial Nerves 9,10
Muscles of the palate, pharynx and larynx are controlled by CN 9/10 neurons from the medulla. CN 9 is mainly sensory supplying the mucous membranes of the soft palate and pharynx; it serves as the afferent limb of the gag reflex. In addition to supplying thoracic and abdominal viscera the CN 10 innervates the muscles of the pharynx, palate and vocal cords and so controls phonation and swallowing. Functions of CN 9/10 are evaluated by testing gag and palatal reflexes, watching swallowing and listening for disturbances of phonation. Lesions are manifested by dysarthria, asymmetric elevation of the soft palate and loss of the gag reflex. Parasympathetic innervation by CN 10 to most viscera is bilateral and so unilateral peripheral or unilateral central lesions tend to produce few symptoms.