The medial rectus muscle is categorized as an extraocular muscle in the eye, which are a group of six muscles that surround the eye. It is small in size but the largest of the extraocular muscles. It is these six muscles that help control the eye's movement. Specifically, it works to keep the pupil closer to the midline of the body. The other five extraocular muscles are the lateral rectus, superior oblique, superior rectus, inferior rectus, and the inferior oblique. The medial rectus muscle helps move the eye up and down and from side to side. It works with the two oblique muscles, whose function is to move the eye in and out. The medial rectus muscle works along with the other five eye muscles to have the eye move and function properly. When the medial rectus muscle is not working correctly and eye movement is affected it is called strabismus. Strabismus can be corrected by ophthamologists, which are doctors specializing in eye conditions.
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In Depth: Medial rectus