What is the primary action of the superior rectus muscle?

What is the primary action of the superior rectus muscle?

• A. Depression and extorsion of the eye.
• B. Abduction of the eye.
• C. Convergence of the eyes.
• D. Elevation and intorsion of the eye.

Answer: (D)

The muscle’s job is to lift the eye and rotate it slightly toward the nose. When the superior rectus contracts, it pulls the eyeball upward, producing elevation. Because of the muscle’s angle of pull, it also causes intorsion, which is the rotation of the top of the eye toward the nose. So its actions are best described as elevation with intorsion. This combination fits the anatomy of the muscle and explains why elevation is its primary effect and why intorsion is a consistent secondary component. Other movements like depression, abduction, or convergence involve different muscles and their primary actions, so they don’t describe what the superior rectus does.

The muscle’s job is to lift the eye and rotate it slightly toward the nose. When the superior rectus contracts, it pulls the eyeball upward, producing elevation. Because of the muscle’s angle of pull, it also causes intorsion, which is the rotation of the top of the eye toward the nose. So its actions are best described as elevation with intorsion. This combination fits the anatomy of the muscle and explains why elevation is its primary effect and why intorsion is a consistent secondary component. Other movements like depression, abduction, or convergence involve different muscles and their primary actions, so they don’t describe what the superior rectus does.