Ace the CPO Exam 2025 – Shine Bright as a Certified Paraoptometric Star!

The primary action of the inferior rectus muscle is to turn the eye downward. This muscle is one of the extraocular muscles that control eye movement. When the inferior rectus contracts, it pulls the eyeball downwards, allowing for downward gaze.

While the other options involve various movements of the eyes, they do not accurately describe the specific function of the inferior rectus muscle. For instance, moving the eye upward is primarily the function of the superior rectus muscle, while the action of moving the eyes away from the nose involves the lateral rectus muscle, and rotation down and inward is a combination of movements that also involves other muscles, particularly the medial rectus alongside the inferior rectus. Thus, option B correctly identifies the main role of the inferior rectus muscle in eye movement.