**Question:** Superior oblique is supplied by -

A. Ciliary ganglion
B. Oculomotor nerve
C. Trochlear nerve
D. Posterior ciliary arteries

**Core Concept:**
The superior oblique muscle is one of the six extraocular muscles responsible for eye movements and maintaining gaze stability. It is a vertical, oblique muscle that helps to rotate the eye downward and to the temple (temporally). The superior oblique muscle is innervated by the trochlear nerve (CN IV), which is a cranial nerve that controls the extraocular muscles.

**Why the Correct Answer is Right:**
The correct answer, C. Trochlear nerve (CN IV), is responsible for innervating the superior oblique muscle. The trochlear nerve is a cranial nerve that supplies motor innervation to the extraocular muscles, including the superior oblique muscle. This explains why the correct answer is D. Trochlear nerve, as it directly connects to the superior oblique muscle and provides it with the necessary motor function.

**Why Each Wrong Option is Incorrect:**
A. Ciliary ganglion: This is an autonomic ganglion that forms part of the sympathetic nervous system and is responsible for reflex control of the ciliary body and iris. It does not innervate the extraocular muscles.

B. Oculomotor nerve (CN III): This cranial nerve controls the extraocular muscles but does not innervate the superior oblique muscle. It primarily controls the lateral rectus, medial rectus, inferior rectus, and superior rectus muscles.

D. Posterior ciliary arteries: These are arteries supplying blood to the eye but are not responsible for innervating the superior oblique muscle. They are part of the ophthalmic artery, which supplies blood to the eye but does not innervate the muscles.

**Clinical Pearl:**
The superior oblique muscle is essential for maintaining a stable gaze and allowing smooth eye movements. In cases of trochlear nerve palsy, patients may experience diplopia (double vision) when looking down and to the side (abduction) due to the lack of innervation to the superior oblique muscle. This condition is known as "superior oblique myasthenia" or "trochlear palsy." The clinical manifestations can be evaluated by a neurologist or ophthalmologist, allowing for a proper diagnosis and treatment plan.