Medial rectus muscle

The medial rectus muscle shares an origin with several other extrinsic eye muscles, the common tendinous ring. It inserts into the anteromedial surface of the eye. This insertion has a width of around 11 mm. It is around 5.5 mm from the corneal limbus. A branch of it enters the muscle around two fifths along its length. It rarely changes position significantly when it contracts, unlike the other extraocular muscles. == Function ==

The medial rectus muscle rotates the eye medially (adduction). It works using a pulley system as it curves around the anterior surface of the eye. == Clinical significance ==

Strabismus Strabismus (lazy eye) may be caused by a medial rectus muscle that is located too high in the orbit of the skull. Sometimes, botulinum toxin may be injected into the medial rectus muscle. This leaves it vulnerable to being compressed (incarcerated) during skull fractures, which can prevent movement of the eye. This usually resolves when skull fractures are fixed. The damage can be minor, such as bruising, or severe, such as cutting through the muscle partially or completely, and nerve injury. == Additional images ==

File:Eye_movements_adductors.jpg|Eye movement of medial rectus muscle, superior view. File:Gray869.png|Horizontal section of the eyeball. File:Gray890.png|Dissection showing origins of right ocular muscles, and nerves entering by the superior orbital fissure. File:ThreeNeuronArc.png |Vestibulo-ocular reflex File:Slide7uu.JPG|Medial rectus muscle File:Slide14uu.JPG|Medial rectus muscle File:Slide3aba.JPG|Extrinsic eye muscle. Nerves of orbita. Deep dissection. File:Slide1abaa.JPG|Extrinsic eye muscle. Nerves of orbita. Deep dissection. File:Slide2abaa.JPG|Extrinsic eye muscle. Nerves of orbita. Deep dissection. File:Slide3abab.JPG|Extrinsic eye muscle. Nerves of orbita. Deep dissection. File:Slide5abab.JPG|Extrinsic eye muscle. Nerves of orbita. Deep dissection. == See also ==