THE CRANIAL NERVES

 

There are twelve cranial nerves: olfactory nerves (I), optic nerve (II), oculomotor nerve (III), trochlear nerve (IV), trigeminal nerve (V), abducent nerve (VI), facial nerve (VII), vestibulocochlear nerve (VIII), glossopharyngeal nerve (IX), vagus nerve (X), accessory nerve (XI) and hypoglossal nerve (XII).

 

The general somatic afference from the head comes mainly from the trigeminal nerve with a few exceptions. These are: the lateral internal auricular nerve (a branch of the facial nerve) for the skin of the concave surface of the ear, the auricular branch of the vagus nerve that is sensory to the external ear canal, the great occipital nerve (a dorsal branch of the C2 spinal nerve) for the skin of the occipital area, the cutaneous branch of the great auricular nerve (a ventral branch of the C2 spinal nerve) for the skin of caudal convex area of the pinna and the neck ventral to the ear, the transverse cervical nerve (a ventral branch of the C2 spinal nerve) for the skin ventral to the mandible.