Which statement about the Trochlear nerve (CN IV) is NOT true?

Which statement about the Trochlear nerve (CN IV) is NOT true?

• A. It has the longest course of the cranial nerves
• B. It is located in the midbrain at the level of the superior colliculus
• C. It is the skinniest cranial nerve
• D. It exits the brainstem dorsally

Answer: (B)

The Trochlear nerve has a distinctive path because its nucleus sits in the dorsal midbrain near the inferior colliculus, and its fibers exit the brainstem on the dorsal surface before wrapping around the brainstem to reach the orbit. That means it is not located at the level of the superior colliculus. The statement placing it at the superior colliculus level is the false one. Remember, this nerve indeed has the smallest diameter and the longest intracranial course, and it exits dorsally from the brainstem.