Which muscle is responsible for eye movements down and out?

The muscle that is primarily responsible for eye movements downward and outward is the inferior oblique muscle. This muscle plays a crucial role in the motion of the eye by allowing it to rotate laterally while also facilitating downward movement. The inferior oblique originates from the anterior part of the orbital rim and inserts at the posterior part of the eye, enabling it to pull the eye in the desired direction during coordinated eye movements.

In contrast, other muscles have different primary functions. The inferior rectus muscle primarily moves the eye downward but does not contribute to lateral movement. The superior oblique muscle primarily assists with downward and medial movement of the eye. The lateral rectus muscle is solely responsible for moving the eye outward (laterally) but does not contribute to downward motion. Therefore, while other muscles may assist in various eye movements, the combined function of the inferior oblique makes it the correct answer for movements specifically downward and outward.