Which is the only nerve which exits the brainstem on dorsal side ?

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).