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
Which is the only nerve which exits the brainstem on dorsal side ? 
Select and explain. 
A. Facial, B. Trigeminal, C. Trochlear, D. Abducent
C: Trochlear
Answer: C: Trochlear 
Explanation: Unique features of trochlear nerve are :?i) Most selender cranial nerve.ii) Only cranial nerve to emerge on the dorsal aspect of brain.iii) Only cranial nerve to undergo complete internal decussation before emerging i.e. right trochlear nerve arises from left trochlear nucleus and vice versa.iv) Has'longest intracranial course (Vagus nerve has overall longest course).v) Thinnest cranial nerve (smallest nerve in terms of the number of axons it contains).