Actions of extraocular muscles

Inferior Oblique is the only muscle arising from the floor of the orbit,all other EOM arise from the orbital apex.

Extra Ocular Muscle attached to the area behind macula-Inferior Oblique.

ACTIONS OF EOM

Primary action: the cation when the eye is in the primary position.

Subsidiary action:additional effects on the position of the eye.

Medial Rectus and Lateral Rectus have only primary action.

All other muscles have a primary and two subsidiary actions.

Primary action of oblique muscles is tortion

Primary action of SR is elevation and IR is depression.

Subsidiary actions

Mnemonic:SINRAD

All superiors are Intorters- SR and SO

All inferiors are Extorters-IR and IO

All Recti are Adductors

All obliques are abductors

Superior Oblique-Copying muslce

Inferior oblique-Stargazers muscle.

SO- depression

IO- Elevation

In abducted  position SR acts as pure elevator.

In adducted position SO pure depressor.

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  1. very helpful

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