Medial Rectus (Left) (Musculus rectus medialis)
Educational content only — not medical advice.
Anatomy
The medial rectus is the largest and strongest extraocular muscle, running along the medial wall of the orbit. Arising from the medial portion of the common tendinous ring, it courses forward to insert into the medial sclera. It functions as a pure adductor of the eye and is critical for binocular convergence during near vision.
Origin & insertion
From the medial margin of the common tendinous ring to the anteromedial aspect of the sclera, approximately 5.5 mm posterior to the corneal limbus.
Action
Adducts the eyeball, turning the pupil medially toward the nose; participates in convergence.
Innervation
Inferior division of the oculomotor nerve (cranial nerve III).
Clinical notes
Internuclear ophthalmoplegia (INO), resulting from damage to the medial longitudinal fasciculus (MLF), impairs adduction of the ipsilateral medial rectus during attempted conjugate lateral gaze.
Related structures
Educational references
FAQ
What is the role of the Medial Rectus (Left)?
The medial rectus is the largest and strongest extraocular muscle, running along the medial wall of the orbit. Arising from the medial portion of the common tendinous ring, it courses forward to insert into the medial sclera. It functions as a pure adductor of the eye and is critical for binocular convergence during near vision.
Why is the Medial Rectus (Left) clinically important?
Internuclear ophthalmoplegia (INO), resulting from damage to the medial longitudinal fasciculus (MLF), impairs adduction of the ipsilateral medial rectus during attempted conjugate lateral gaze.
Source & license
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