This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Trochlear nerve all true except: 
Select and explain. 
A. Longest intracranial course, B. Arises from dorsum of brainstem, C. Supply ipsilateral superior oblique muscle, D. Enter orbit through sup.
C: Supply ipsilateral superior oblique muscle
Answer: C: Supply ipsilateral superior oblique muscle 
Explanation: C i.e. Supplies ipsilateral superior oblique muscle Trochlear nerve is thinnest nerve. It is the only nerve to emerge from dorsum of brain stemQ has longest intracranial course. It enters orbit through outer pa of superior orbital fissure (ie lateral to annulus of Zinn)Q and supplies superior oblique muscle. Because it's a crossed cranial nerve (with decussation in mid brain), the trochlear nerve nucleus supplies contralateral superior oblique muscle.