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.
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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
- No cutaneous sensory territory - this nerve is purely motor.
Frequently asked questions
What type of nerve is the trochlear nerve (CN IV)?
The trochlear nerve (CN IV) is motor (cranial nerve).
What muscles does the trochlear nerve (CN IV) supply?
The trochlear nerve (CN IV) supplies the superior oblique muscle (depresses, abducts, and intorts the eye).
What is the sensory distribution of the trochlear nerve (CN IV)?
No cutaneous sensory territory - this nerve is purely motor.
What is the course of the trochlear nerve (CN IV)?
Exits the dorsal midbrain, has the longest intracranial course, passes through the cavernous sinus and superior orbital fissure.