Final answer:
When a patient with right CN4 palsy looks down and to the left, their right eye will be unable to move downward, while their left eye will move inward. This can result in diplopia or double vision.
Step-by-step explanation:
When a patient with right CN4 palsy is asked to look down and to the left, their eyes will exhibit certain characteristics. The fourth cranial nerve, also known as the trochlear nerve, controls the superior oblique muscle, which is responsible for downward and inward movement of the eye. Dysfunction of this nerve can result in the inability to move the eye downward and to the side properly.
In the case of right CN4 palsy, when the patient is asked to look down and to the left, their right eye will be unable to move downward and their left eye will move inward toward the nose. This is because the affected trochlear nerve on the right side cannot properly innervate the superior oblique muscle, leading to weakness in downward eye movement on that side.
As a result, the patient may experience diplopia, or double vision, when looking in this direction due to the misalignment of the eyes. The affected eye will be deviated upward and outward, while the unaffected eye will be looking downward and inward toward the nose.