Thee cranial nerves have been grouped together because isolated lesions of one nerve alone are rarely encountered. The glosopharyngeal nerve transmits taste and common sensation from the posterior one third of the tongue; the vague nerve is the parasympathetic nerve for the viscera of the thorax an upper part of the abdoment and also supplies somatic motor fibers to the soft palate and the larynx; the accessory nerve supplies the trapezium and stern mastoid muscles. Unilateral lesions disturb their somatic function but do into appreciable affect visceral function. These nerves or their nuclei may be involved by disease of the medulla such as syringobulbia or in their course across the posterior fossa a by neoplasm and basal meningitis. Lesion at the jugular foremen, such ashrombophlebitis of the internal jugular vein following suppuration in the skull or neck may involve all three nerves as they emerge from the skull.
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