Muscles of eye movement Flashcards
how many muscles are involved in control of eyeball itself?
six muscles
how can muscles of eye movement be divided?
4 recti muscles
2 oblique muscles
what are the 4 recti muscles involved in the eye movement?
superior rectus, inferior rectus, medial rectus and lateral rectus
where do the 4 recti muscles originate from?
common tendinous ring
what is the common tendinous ring?
a ring of fibrous tissue, which surrounds the optic canal at the back of the orbit
what does the common tendinous ring surround?
the optic canal at the back of the orbit
where do the recti muscles pass from their origin?
pass anteriorly to attach to the sclera of the eyeball
what does recti mean?
recti = straight
recti muscles have a direct path from origin to attachment
how do you remember the innervation of the muscles to the eyes?
LR6SO4R3
lateral rectus = CN 6
superior oblique = CN 4
the rest = CN 3
how many oblique muscles are there?
There are two oblique muscles
what are the 3 oblique muscles?
superior and inferior obliques
where do the oblique muscles originate?
Unlike the recti group of muscles, they do not originate from the common tendinous ring
From their origin, which path do the oblique muscles take?
the oblique muscles take an angular approach to the eyeball (in contrast to the straight approach of the recti muscles)
where do oblique muscles attach?
to the posterior surface of the sclera
describe origin of the recti muscles
they all originate from the common tendinous ring (superior, inferior, middle, lateral) which is a group of fibrous tissue surrounding the optic canal at the back of the orbit
describe the attachment of the recti muscles
they all attach to the anterior sclera (superior, inferior, medial, lateral) e.g. superior anterior sclera etc.
innervation of recti muscles
superior, inferior, medial = CN III (oculomotor)
lateral rectus = CN VI (abducens)
function of the 4 recti muscles
superior = elevate eyeball inferior = depress eyeball medial = adduct eyeball lateral = ABduct eyeball
what else does inferior rectus contribute to (eye movement)?
adduction and lateral rotation of the eyeball
what else does superior rectus contribute to (eye movement)?
adduction and medial rotation of the eyeball
what do both superior and inferior rectus contribute to (eye movement)?
adduction of the eyeballs
innervation of superior and inferior oblique?
SO4
IO = CN III (R3)
origin of superior oblique?
from the body of the sphenoid bone
attachment of superior oblique?
Its tendon passes through a trochlear, and then attaches to the sclera of the eye, posterior to the superior rectus
action of superior oblique?
Depresses, ABducts and medially rotates the eyeball
intorsion of the eyeball
origin of inferior oblique?
anterior aspect of the orbital floor
attachment of inferior oblique?
sclera of the eye, posterior to the lateral rectus
action of internal oblique?
Elevates, abducts and laterally rotates the eyeball
extorsion of eyeball
