Extraocular Muscles Flashcards by Maisie Lygo

what is the role of the extraocular muscles?

control the movements of the eyeball and the superior eyelid

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how many extraocular muscles are there?

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list the extraocular muscles

levator palpebrae superioris
superior rectus
inferior rectus
medial rectus
lateral rectus
inferior oblique
superior obliue

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what extraocular muscles are responsible for eye movement?

recti and oblique muscles

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what extraocular muscles are responsible for superior eyelid movement?

levator palpebrae superioris

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levator palpebrae superioris
* origin?
* insertion?

lesser wing of sphenoid, above optic foramen
superior tarsal plate of upper eyelid

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a portion of the LPS contains a collection of smooth muscle fibres - what are these?

superior tarsal muscles

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what is the innervation of the LPS?

oculomotor nerve (CNIII)

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what is the superior tarsal muscle innervated by?

sympathetic nevous system

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what is the action of the LPS?

elevates upper eyelid

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what is the annulus of zinn?

tendinous ring of fibrous tissue that surrounds the optic canal at the back of the orbit

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superior rectus
* origin?
* insertion?

origin - annulus of zinn
insertion - superior anterior sclera

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what is the action of the superior rectus?

elevation
adduction and intorsion

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what is the innervation of the superior rectus?

oculomotor nerve (CN III)

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inferior rectus
* origin?
* insertion?

origin - annulus of zinn
insertion - inferior anterior sclera

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what is the action of the inferior rectus muscle?

depression
adduction and extorsion

what innervates the inferior rectus muscle?

oculomotor nerve (CN III)

medial rectus
* origin?
* insertion?

origin - annulus of zinn
insertion - medial anterior sclera

what is the action of the medial rectus?

adducts the eyeball

what is the innervation of the medial rectus?

oculomotor nerve (CN III)

lateral rectus
* origin?
* insertion?

origin - annulus of zinn
insertion - lateral anterior sclera

what is the action of the lateral rectus?

abducts the eye

what is the innervation of the lateral rectus?

abducens nerve (CN VI)

superior oblique
* origin?
* insertion?

origin - body of sphenoid
insertion - superior posterolateral sclera

what is the action of the superior oblique?

* **intorsion** * depression + abduction

what is the innervation of the superior oblique?

trochlear nerve (CNIV)

inferior oblique * origin? * insertion?

* origin - anterior orbital floor * insertion - inferior posterolateral sclera

what is the action of the inferior oblique muscle?

* **extorsion** * abduction, elevation

what is the innervation of the inferior oblique muscle?

oculomotor nerve (CN III)

yawing

adduction and abduction

pitching

elevation and depression

cranial nerve palsy - damage to oculomotor nerve?

* eye displaced laterally by lateral rectus * displaced inferiorly by superior oblique "down and out"

cranial nerve palsy - damage to trochlear nerve?

* superior oblique muscle paralysed * no obvious effect to resting orientation * complaints of diplopia and may develop head tilt away from site

cranial nerve palsy - damage to abducens nerve?

* paralyse lateral rectus muscle * affected eye adducts by resting tone of medial rectus

Label the extraocular muscles

Label the muscles of the upper eye

Label the eye movements