Superior, Lateral, Inferior And Medial Rectus Flashcards
(7 cards)
Superior rectus
Origin
Distance from limbus to insertion
Muscle length
Angle to sagittal plane
Blood supply
Nerve supply
Origin - annulus of zinn
Distance from limbus to insertion - 7.5mm
Muscle length - 42mm (longest rectus)
Angle to sagittal plane - 23°
Blood supply - superior muscle branch of ophthalmic artery. Superior ophthalmic vein.
Nerve supply - superior division of oculomotor - CN111
Inferior rectus
Origin
Distance from limbus
Muscle length
Angle to sagittal plane
Blood supply
Nerve supply
Origin - annulus of zinn
Distance from limbus - 6.5mm
Muscle length - 40mm (shortest rectus)
Angle to sagittal plane - 23° (mirrors superior)
Blood supply - inferior muscular branch of ophthalmic artery and intraorbital artery. Inferior ophthalmic vein.
Nerve supply - inferior division of oculomotor CN111
Medial rectus
Origin
Distance from limbus
Muscle length
Angle to horizontal plane
Blood supply
Nerve supply
Origin - annulus of zinn
Distance - 5.5mm
Muscle length - 41mm
Angle to horizontal plane - attached along the horizontal plane
Blood supply - inferior muscular branch of ophthalmic artery. Inferior ophthalmic vein.
Nerve supply - inferior division of oculomotor CN111
Lateral rectus
Origin
Distance from limbus
Muscle length
Angle to horizontal plane
Blood supply
Nerve supply
Origin - annulus of zinn
Distance - 7.0mm
Muscle length - 41mm
Angle to horizontal plane - attached along H’ plane
Blood supply - superior muscular branch of ophthalmic artery and lateral artery. Inferior ophthalmic vein.
Nerve supply - abducent nerve CNVI
Superior oblique
Origin
Distance from equator
Muscle length (inc. tendon)
Angle to sagittal plane
Blood supply
Nerve supply
Origin - apex of orbit, superior and nasal to annulus of zinn
Distance from equator - 6mm
Muscle length (inc tendon) - 60-65mm (longest EOM)
Angle to sagittal plane - distal tendon 51-54°
Blood supply - superior muscular branch of ophthalmic artery. Superior ophthalmic vein.
Nerve supply - trochlear nerve CNIV
Inferior oblique
Origin
Distance from equator
Muscle length (inc tendon)
Angle to sagittal plane
Blood supply
Nerve supply
Origin - lateral edge of lacrimal fossa of lacrimal bone
Distance from equator - level with posterior pole
Muscle length - 37mm (shortest EOM)
Angle to sagittal plane - 51° mirrors S.O
Blood supply - inferior muscular branch of ophthalmic artery. Inferior ophthalmic vein.
Nerve supply - inferior division of oculomotor nerve CN111
The trochlea
Muscle runs along the medial wall of the orbit.
Distal tendon reflects through trochlea.
Ring of fibro-cartridge housed in trochlea fossa of frontal bone - upper nasal corner of orbit.
