Which of the following statements about the trochlear nerve (CN IV) is correct?

• A It emerges from the ventral surface of the midbrain and decussates incompletely
• B It supplies the inferior oblique along with the inferior division of the oculomotor nerve
• C It passes through the foramen rotundum to reach the orbit
• D It is the only cranial nerve that emerges from the dorsal aspect of the brainstem and supplies the contralateral superior oblique ✓

Explanation

The trochlear nerve arises from the trochlear nucleus, decussates completely in the superior medullary velum, and emerges from the dorsal surface of the midbrain just below the inferior colliculus. It is the only cranial nerve to exit dorsally and it innervates the contralateral superior oblique. It enters the orbit through the superior orbital fissure, not the foramen rotundum, and the inferior oblique is supplied by CN III.

Reference: Gray's Anatomy for Students, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.