Question

Name the 2${}^{nd}$, 3${}^{rd}$ and 8${}^{th}$ cranial nerves in man and write a function of each.

Answer 1

The second (CN-II) cranial nerve is the optic nerve. It is responsible for the vision (eyesight). Each optic nerve contains approximately a million nerve fibres that receive information from the rod and cone cells of the retina.

The third (CN-III) cranial nerve is oculomotor. It moves the eyeball and eyelid, adjusts the lens of the eye for near vision. It also constricts the pupil of the eye via the motor fibres distributed to the muscles located in the eye.

The eighth (CN-VIII) cranial nerve is vestibulocochlear. It contains two branches. One of the branches is for the vestibular nerve which aids in equilibrium by carrying impulses from the semicircular canals, providing information about movement, posture and balance. The another branch is for the cochlear nerve which carries impulses from the cochlea and is known as the nerve of hearing.