Medial rectus muscle

Medial rectus
Rectus muscles: 2 = superior, 3 = inferior, 4 = medial, 5 = lateral Oblique muscles: 6 = superior, 8 = inferior Other muscle: 9 = levator palpebrae superioris Other structures: 1 = Annulus of Zinn, 7 = Trochlea, 10 = Superior tarsus, 11 = Sclera, 12 = Optic nerve
Figure showing the mode of innervation of the Recti medialis and lateralis of the eye.
Details
Origin	annulus of Zinn at the orbital apex
Insertion	5.5 mm medial to the limbus
Nerve	inferior division of the oculomotor nerve
Actions	adducts the eyeball (makes it move inwards)
Identifiers
Latin	musculus rectus medialis bulbi
TA98	A15.2.07.012
TA2	2044
FMA	49037
Anatomical terms of muscle

The medial rectus muscle is a muscle in the orbit.

As with most of the muscles of the orbit, it is innervated by the inferior division of the oculomotor nerve (Cranial Nerve III).

This muscle shares an origin with several other extrinsic eye muscles, the anulus tendineus, or common tendon.

It is the largest of the extraocular muscles and its only action is adduction of the eyeball. Its function is to bring the pupil closer to the midline of the body. It is tested clinically by asking the patient to look medially.

Additional images

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  Eye movement of medial rectus muscle, superior view.
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  Horizontal section of the eyeball.
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  Dissection showing origins of right ocular muscles, and nerves entering by the superior orbital fissure.
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  Vestibulo-ocular reflex
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  Medial rectus muscle
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  Medial rectus muscle
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  Extrinsic eye muscle. Nerves of orbita. Deep dissection.
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  Extrinsic eye muscle. Nerves of orbita. Deep dissection.
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  Extrinsic eye muscle. Nerves of orbita. Deep dissection.
• 
  Extrinsic eye muscle. Nerves of orbita. Deep dissection.
• 
  Extrinsic eye muscle. Nerves of orbita. Deep dissection.
• 
  Extrinsic eye muscle. Nerves of orbita. Deep dissection.

External links

• Anatomy figure: 29:01-06 at Human Anatomy Online, SUNY Downstate Medical Center
• lesson3 at The Anatomy Lesson by Wesley Norman (Georgetown University) (orbit4)
• Diagram at howstuffworks.com