GROSS ANATOMY

Detailed explanation-1: -The fourth cranial nerve is the trochlear nerve and contains only somatic motor fibers. It supplies a single extraocular muscle – the superior oblique – a muscle responsible for intorsion of the eye with a small amount of abduction and depression. It arises from the trochlear nucleus at the level of the midbrain.

Detailed explanation-2: -The trochlear nerve (IV) exits from the caudal portion of the midbrain and supplies the superior oblique muscle.

Detailed explanation-3: -Abducens Nerve (CN VI): This nerve only innervates one muscle of the eye, the lateral rectus muscle.

Detailed explanation-4: -The oculomotor nerve is the third cranial nerve (CN III). It allows movement of the eye muscles, constriction of the pupil, focusing the eyes and the position of the upper eyelid.

Detailed explanation-5: -The trochlear nerve (CN IV) provides motor function to the superior oblique muscle of the eye. The trigeminal nerve (CN V) is the principal sensory supply to the head (face, teeth, sinuses, etc.); it also provides motor function to the muscles of mastication.