Lateral Rectus
Extraocular · Head & Neck
The lateral rectus is the extraocular muscle responsible for turning the eye outward. It arises from the lateral part of the common tendinous ring, the annulus of Zinn, bridging the superior orbital fissure, and runs forward along the lateral wall of the orbit to insert into the lateral sclera about 7 mm behind the corneal limbus. Its horizontal line of pull produces pure abduction, moving the pupil away from the midline. Unlike most of the extraocular muscles, it is not supplied by the oculomotor nerve but by the abducens nerve (CN VI), a fact captured by the classic mnemonic LR6.
Origin, Insertion, Action & Nerve
Origin
Lateral part of the common tendinous ring (annulus of Zinn), bridging the superior orbital fissure
Insertion
Lateral sclera, ~7 mm posterior to the corneal limbus
Action
Abducts the eyeball
Nerve
Abducens nerve (CN VI)
Attachments explained
The Lateral Rectus is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Lateral part of the common tendinous ring (annulus of Zinn), bridging the superior orbital fissure
Insertion
Lateral sclera, ~7 mm posterior to the corneal limbus
Action & function
When the Lateral Rectus contracts, it produces the following movement: Abducts the eyeball.
As part of the Extraocular group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Lateral Rectus receives its nerve supply from the Abducens nerve (CN VI).
Because a muscle can only contract when its nerve is intact, injury to the Abducens nerve can weaken or paralyse the Lateral Rectus, impairing the movements it normally produces (abducts the eyeball). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Lateral Rectus (the OIANS method)
Study the lateral rectus as the direct antagonist of the medial rectus: it runs straight forward along the lateral orbital wall and produces pure abduction, turning the eye away from the nose. Because its action is uncomplicated, the muscle is defined chiefly by its unique nerve rather than by any secondary movement.
The essential fact is the innervation, summarised in the mnemonic LR6 SO4, meaning the lateral rectus is CN VI and the superior oblique is CN IV. Because the abducens nerve has a long intracranial course, it is easily damaged, and a sixth nerve palsy leaves the eye adducted and unable to abduct, producing horizontal double vision. Linking abduction failure to CN VI cements both anatomy and clinical sign.
Frequently asked questions
Where is the Lateral Rectus located?
The Lateral Rectus is a muscle of the Extraocular group, located in the Head & Neck.
What is the origin of the Lateral Rectus?
Lateral part of the common tendinous ring (annulus of Zinn), bridging the superior orbital fissure
What is the insertion of the Lateral Rectus?
Lateral sclera, ~7 mm posterior to the corneal limbus
What movements does the Lateral Rectus produce?
Abducts the eyeball
What nerve supplies the Lateral Rectus?
Abducens nerve (CN VI)
Is the Lateral Rectus free to study in OIANS?
The Lateral Rectus is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Head & Neck is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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