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Extraocular muscles
Anatomy & Optics
Key Points
- •Six EOMs (4 recti + 2 obliques) control eye movements; all except the inferior oblique arise from the annulus of Zinn; innervation follows LR₆SO₄, rest CN III
- •Spiral of Tillaux: recti insertions from limbus - MR 5.5 mm, IR 6.5 mm, LR 6.9 mm, SR 7.7 mm - critical for strabismus surgery planning
- •Each rectus carries 2 ACAs except the LR (1 ACA); detaching ≥3 recti risks anterior segment ischaemia; the LR is safest to detach
- •Lockwood's ligament (IR + IO sheaths + check ligaments of MR/LR) suspends the globe inferiorly; check ligaments limit excessive eye rotation and connect muscle sheaths to orbital walls
- •Tenon's capsule envelops the globe; EOMs pierce it and receive fascial sleeves that form the pulley system - functionally determines effective EOM paths and actions
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- Definition
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- Aetiology and causes
- Pathogenesis
- Classification
- Risk factors and associations