Extraocular Muscles: Anatomy And Movements
Write about the origin, insertion, nerve supply and actions of the extrinsic muscles of the eyeball.
Answer.
Extrinsic Muscles of Eyeball Origin
Four recti: From common tendinous ring.
Superior oblique: From the body of the sphenoid superomedial to the optic canal.
Inferior oblique: From a rough impression in the anteromedial part/angle of the floor of the orbit.
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Extrinsic Muscles of Eyeball Insertion
Four recti: Into sclera, a little posterior to the limbus (i.e. corneoscleral junction). Distance from the cornea is as follows:
SR = 7.7 mm; IR = 6.5 mm; MR = 5.5 mm; LR = 6.9 mm
Superior oblique: Into sclera, behind the equator in the posterosuperior quadrant of the eyeball between SR and LR.
Inferior oblique: Into the sclera, behind the equator in the posteroinferior quadrant of the eyeball.
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Extrinsic Muscles of the Eyeball Nerve supply
All the extrinsic muscles of the eyeball are supplied by CN 3, except the superior oblique, which is supplied by CN 4 and the lateral rectus which is supplied by CN 6.
Mnemonic: LR6SO4 (LR, lateral rectus; SO, superior oblique)
Extrinsic Muscles of Eyeball Actions
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Actions of Extrinsic Muscles of the Eyeball
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