Ocular Anatomy 12 Extraocular Muscles Flashcards
What is the origin of the rectus muscles?
Common tendinous ring
Annulus of Zinn at the orbital apex
Where do the rectus muscles insert?
MR 5.5mm from limbus
IR 6.5mm from limbus
LR 6.9mm from limbus
SR 7.7mm from limbus
Insertions form spiral of Tilaux MILS
What are the length of the tendon of each rectus?
MR 3.7mm
IR 5.5mm
SR 5.8mm
LR 8.8mm
What is the origin of the superior oblique msucle?
Body of sphenoid bone outside the tendinous ring
Gives rise to a rounded tendon that passes through trochlea at superonasal orbit
Superonasal to CTR and optic nerve
What is the origin of the inferior oblique
From within the floor of the orbital rim
What is the path of the recti muscles?
Pass anteriorly
Uperior and inferior recti pass forwards at approximately 25 degrees to optical axis
What is the path of the superior oblique muscle? Insertion?
Pulls forward at an angle of approx 55 degrees to the nasal side of the globe’s visual axis with the eye in primary position.
Enters Tenon’s capsule
Passes inferiorly to superior rectus before inserting posterior to equator of globe
Inserts on postero supero lateral quadrant
What is the path of the inferior oblique muscle? Insertion?
Pulls forward at an angle of approximately 50 degrees
Passes inferiorly to superior rectus before inserting posterior to equator of globe
Inserts on postero infero lateral quadrant
What does the superior division of the occulomotor nerve supply?
SR
Levator palpebrae superiorisW
What does the inferior division of the oculomotor nerve supply?
MR
IR
IO
Where does the occulomotor nerve enter the orbit?
Superior orbital fissure
What supplies SO and LR?
SO - trochlear nerve 4th
LR - abducens nerve 6th
What nerves enter the orbit outside the CTR?
Lacrimal nerve
Frontal component of ophthalmic nerve
Trochlear nerve
Action (primary, secondary, tertiary) of medial rectus
Adduction, rotation around y-axis
Action (primary, secondary, tertiary) of lateral rectus
Abduction, rotation around y-axis
