GROSS ANATOMY

Detailed explanation-1: -The fourth cranial nerve (trochlear nerve) has the longest intracranial course; it is the only cranial nerve that has a dorsal exit from the brainstem (figure 1). It begins in the midbrain at the level of the inferior colliculus as fascicles extending from the fourth nerve nuclei.

Detailed explanation-2: -The trochlear nerve is the fourth cranial nerve (CN IV) and one of the ocular motor nerves that controls eye movement. The trochlear nerve, while the smallest of the cranial nerves, has the longest intracranial course as it is the only nerve to have a dorsal exit from the brainstem.

Detailed explanation-3: -Of all the cranial nerves, the abducens nerve has the second longest intracranial course. It is located in the pons at the floor of the fourth ventricle, at the same level as the facial colliculus. In fact, the axons of the facial nerve loop around the posterior aspect of the abducens nucleus.

Detailed explanation-4: –The trochlear nerve is the smallest cranial nerve. It is the fourth cranial nerve. Emerging from the brain, it has the shortest course as it terminates by innervating a muscle present in the eye.

Detailed explanation-5: -The sixth nerve has the longest subarachnoid course of all cranial nerves and innervates the ipsilateral lateral rectus (LR) which abducts the eye.