Inferior rectus

A muscle responsible for downward eye movement and assists in rotation.

The inferior rectus is one of the six extraocular muscles that control eye movement. It is specifically responsible for depressing the eyeball, allowing for downward movement, and assisting in the adduction and medial rotation of the eye. This muscle plays a vital role in coordinating gaze direction.

Terminologia Anatomica

musculus rectus inferior

System

Muscular system

Function

The primary function of the inferior rectus muscle is to facilitate the downward movement of the eyeball. This action is essential for a variety of visual tasks, such as reading or looking downwards. Additionally, the inferior rectus works in concert with the other extraocular muscles to achieve precise eye coordination and positioning. For instance, when the eye looks downward, the inferior rectus contracts while the superior rectus relaxes, maintaining a balance that allows for smooth and controlled movements. This muscle is also involved in stabilizing the position of the eye when the head moves, helping to maintain focus on objects while in motion.

Location

The inferior rectus muscle is located in the orbit, which is the bony cavity that houses the eyeball. It originates from the common tendinous ring, also known as the annulus of Zinn, situated at the back of the orbit. The muscle runs forward and inserts onto the inferior surface of the eyeball. Its positioning allows it to pull the eyeball downward when it contracts, highlighting its critical role in eye movement.

Did You Know?

The inferior rectus is one of the most frequently tested muscles in clinical examinations related to eye movement.
Dysfunction of the inferior rectus muscle can lead to conditions like diplopia, or double vision, particularly when looking down.
This muscle is unique in that it not only depresses the eye but also helps with its inward movement.