Nerve
Trochlear nerve (CN IV)
Superior oblique muscle
High-yield
Supplies only superior oblique (SO4); palsy → vertical diplopia worse on looking down (trouble descending stairs); head tilts away.
Overview
The fourth cranial nerve, the only one to exit the dorsal brainstem and the smallest, supplying a single extraocular muscle.
Reference facts
- Roots
Motor (cranial nerve)
- Course
Exits the dorsal midbrain, has the longest intracranial course, passes through the cavernous sinus and superior orbital fissure
- Motor
Superior oblique muscle (depresses, abducts, and intorts the eye)
- Sensory
None