**Core Concept**
The superior oblique muscle is one of the six extraocular muscles responsible for the movement of the eyeball. It plays a crucial role in the rotational movement of the eye, particularly in the downward and inward movement of the eyeball.

**Why the Correct Answer is Right**
The superior oblique muscle functions to rotate the eyeball in two main ways: it abducts the eyeball (moves it away from the midline of the body) and it depresses it (moves it downward). This is achieved through its insertion into the sclera of the eye, near the equator. When the muscle contracts, it pulls the eyeball downward and inward, allowing for precise movement and focusing of the gaze. The superior oblique muscle is innervated by the trochlear nerve (cranial nerve IV), which is the thinnest cranial nerve and responsible for controlling the muscle's movement.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the superior oblique muscle does not primarily function to rotate the eyeball in the upward direction. That function is actually performed by the superior rectus muscle.
**Option B:** This option is incorrect because the superior oblique muscle does not primarily function to rotate the eyeball in the outward direction. That function is actually performed by the lateral rectus muscle.
**Option C:** This option is incorrect because the superior oblique muscle does not primarily function to rotate the eyeball in the upward and outward direction. This function is actually performed by a combination of the superior rectus and lateral rectus muscles.

**Clinical Pearl / High-Yield Fact**
The superior oblique muscle is often affected in cases of trochlear nerve palsy, which can result in double vision and difficulty with downward gaze. This condition is a classic example of a cranial nerve palsy and is often seen in clinical practice.

**Correct Answer:** C.