The medial rectus is the primary adductor of the eye and the strongest extra-ocular muscle by cross-sectional area, reflecting the frequency and power demands of convergence for near vision. Medial rectus overaction (esotropia) is the most common strabismus in children. Medial rectus recession is the most commonly performed strabismus surgical procedure, weakening its adduction force to reduce esotropia.
| Origin | Common tendinous ring (annulus of Zinn) |
|---|---|
| Insertion | Medial sclera 5.5 mm from the limbus — the strongest extra-ocular muscle by cross-sectional area |
| Nerve Supply | Inferior division of CN III |
| Blood Supply | Ophthalmic artery |
| Actions | Adduction of the eye — moves the eye toward the nose |
|---|
Convergence — the simultaneous bilateral medial rectus contraction that occurs during near vision — is a disconjugate eye movement (eyes moving in opposite directions) rather than a conjugate saccade, reflecting a unique neural control pathway that is the last visual skill to mature and the first to fail with fatigue.
Medial rectus recession is the workhorse procedure of paediatric strabismus surgery. Bilateral medial rectus recession for infantile esotropia restores binocular vision when performed before age 2 years of age while cortical binocular pathways are still plastic. The medial rectus is also weakened in exotropia management by lateral rectus recession combined with medial rectus resection.
Not directly palpable. Assessed by corneal light reflex (Hirschberg) and cover-uncover test.
Medial rectus overaction causing eye crossing in infancy requiring early bilateral medial rectus recession before age 2 to establish binocular vision.
