<P> The oculomotor nerve (III), trochlear nerve (IV) and abducens nerve (VI) coordinate eye movement . </P> <P> Damage to nerves III, IV, or VI may affect the movement of the eyeball (globe). Both or one eye may be affected; in either case double vision (diplopia) will likely occur because the movements of the eyes are no longer synchronized . Nerves III, IV and VI are tested by observing how the eye follows an object in different directions . This object may be a finger or a pin, and may be moved at different directions to test for pursuit velocity . If the eyes do not work together, the most likely cause is damage to a specific cranial nerve or its nuclei . </P> <P> Damage to the oculomotor nerve (III) can cause double vision (diplopia) and inability to coordinate the movements of both eyes (strabismus), also eyelid drooping (ptosis) and pupil dilation (mydriasis). Lesions may also lead to inability to open the eye due to paralysis of the levator palpebrae muscle . Individuals suffering from a lesion to the oculomotor nerve may compensate by tilting their heads to alleviate symptoms due to paralysis of one or more of the eye muscles it controls . </P> <P> Damage to the trochlear nerve (IV) can also cause diplopia with the eye adducted and elevated . The result will be an eye which cannot move downwards properly (especially downwards when in an inward position). This is due to impairment in the superior oblique muscle, which is innervated by the trochlear nerve . </P>

The only cranial nerve that is attached to the cerebrum is the