Extraocular Muscles Flashcards
what is the role of the extraocular muscles?
control the movements of the eyeball and the superior eyelid
how many extraocular muscles are there?
7
list the extraocular muscles
- levator palpebrae superioris
- superior rectus
- inferior rectus
- medial rectus
- lateral rectus
- inferior oblique
- superior obliue
what extraocular muscles are responsible for eye movement?
recti and oblique muscles
what extraocular muscles are responsible for superior eyelid movement?
levator palpebrae superioris
levator palpebrae superioris
* origin?
* insertion?
- lesser wing of sphenoid, above optic foramen
- superior tarsal plate of upper eyelid
a portion of the LPS contains a collection of smooth muscle fibres - what are these?
superior tarsal muscles
what is the innervation of the LPS?
oculomotor nerve (CNIII)
what is the superior tarsal muscle innervated by?
sympathetic nevous system
what is the action of the LPS?
elevates upper eyelid
what is the annulus of zinn?
tendinous ring of fibrous tissue that surrounds the optic canal at the back of the orbit
superior rectus
* origin?
* insertion?
- origin - annulus of zinn
- insertion - superior anterior sclera
what is the action of the superior rectus?
- elevation
- adduction and intorsion
what is the innervation of the superior rectus?
oculomotor nerve (CN III)
inferior rectus
* origin?
* insertion?
- origin - annulus of zinn
- insertion - inferior anterior sclera
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
