EOMs Flashcards
What is the embryonic derivative of the EOMs?
Mesodermal origin
When do the EOMs begin developing
Week 3 of gestation
When are the EOMs fully formed
6 months, but continue to enlarge during remaining part of gestation
Microaantomy of EMOs
Striated muscles with actin and myosin
Eye movements are _______ and more __________ due to unique combination of white (fast) and red (slow) muscle fibers
Faster
Fatigue resistant
What are the two layers of the EOMS
- orbital (superficially)
- globular (deeper)
What are the 4 rectus muscles
Inferior
Superior
Medial
Lateral
What are the two oblique muscles
Superior and inferior
What two muscles only have 1 action?
Medial and lateral rectus
Primary action of medial rectus
Auction
Primary action of lateral rectus
Abduction
Primary, secondary, and tertiary action of superior rectus
Elevation
Intorsion
Adduction
Primary, secondary, an tertiary actions of the inferior rectus
Depression
Extortion
Adduction
Primary, secondary, and tertiary actions of superior oblique
Intorsion
Depression
Abduction
Primary, secondary, and tertiary actions of inferior oblique
Extortion
Elevation
Abduction
What is the primary action for the obliques?
Torsions
Where do all 4 of the recti muscles originate?
Annulus of zinn or common tendinous ring
What structure is the annulus of zinn in?
Oculomotor foramen
What passes through the oculomotor foramen?
- oculomotor nerve
- optic nerve
- ophthalmic artery
- abducens nerve
- nasociliary nerve
What EOM inserts closest to the limbus?
Medial rectus
What is the spiral of tillaux
The insertions of the EOMs relative to the limbus become further and further from the limbus going clockwise(OD)
Order of spiral of tillaux
Medial rectus
Lateral rectus
Superior rectus
Inferior rectus
Origin of levator palpebrae superioris
Lesser wing of sphenoid bone
Action of levator palpebrae superioris
Elevation of upper lid
Innervation of levator palpebrae superioris
CNIII
How does the superior rectus run?
Passes beneath levator, above superior oblique on globe
Primary action of the superior rectus
Elevation