Extraocular Muscles Flashcards
What are the 6 Extraocular Muscles?
Superior Rectus Inferior Rectus Medial Rectus Lateral Rectus Superior Oblique Inferior Oblique
What are the 3 Cranial Nerves that innervates the EOM’s?
CN III
CN IV
CN VI
What does CN III innervate?
Superior Recuts
Medial Rectus
Inferior Rectus
Inferior Oblique
What does CN IV innervate?
Superior Oblique
What does CN VI innervate?
Lateral Rectus
What is the Primary Action of Lateral Rectus?
Abduction
What is the primary action of Medial Rectus?
Adduction
What is the primary action of Superior Rectus?
Elevation
What is the primary action of Inferior Rectus?
Depression
What is the primary action of Superior Oblique?
Intorsion
What is the primary action of Inferior Oblique?
Extorsion
What is the term called when muscles from each eye work together to move the eyes together?
Yoke Muscles
What is the term called when a muscle in one eye is sent a signal to move, the Yoke muscle in the other eye receive equal innervation?
different
Hering’s Law of Equal Innervation
What is the term called when a signal of the muscle is sent to CONTRACT, the opposing muscles in that eye is to RELAX
Sherrington’s Law of Recriprocal Innervation
When the eye is ABDUCTED, what is the main ELEVATOR and the main DEPRESSOR?
Elevator : Superior Rectus
Depressor : Inferior Rectus
When the eyes are turned inwards (adducted) what eom has a DEPRESSION role and a ELEVATION role?
Depression : Superior Oblique
Elevation : Inferior Oblique
When the eyes are straight / turned outward (abducted) what has the ELEVATION role and DEPRESSION role. What muscle is for INTORSION?
Elevation : Superior Rectus
Depression : Inferior Recuts
Intorsion : Superior Rectus
What occurs when the visual axis of the eyes are NOT aligned? The eyes appear to look like they are in different directions.
Strabismus
What is the amount of deviation measured in?
Prism Dioptres
Direction of Deviation :
Eye turns down
Hypotropia
Direction of Deviation :
Eye turns up
Hypertropia
Direction of Deviation :
Eye turns out
Exotropia
Direction of Deviation :
Eye turns in
Esotropia `
What is the Tertiary Action for Superior/Inferior Rectus?
Adduct
What is the Tertiary Action for Superior/Inferior Oblique?
Abduct
What is the Secondary Action of Lateral Rectus?
None
What is the Secondary Action of Medial Rectus?
None
What is the Secondary Action of Superior Rectus?
Intorsion
What is the Secondary Action of Inferior Rectus?
Extorsion
What is the Secondary Action of Superior Oblique?
Depression
What is the Secondary Action of Inferior Oblique?
Elevation
What syndrome is the incorrect innervation of the EOM’s by CN’s?
- born with it
- patients have a limited ability to abduct or adduct or both.
- muscles stretch when they should be tightened
Duane Syndrome
What syndrome is when the tendons could be tight or short. Usually congenital
Brown Syndrome
What are tests for the light reflexes?
Hirschberg and Krimsky
What are the Stereovision tests?
Randot
Stereofly
What test is to evaluate Strabismus?
Randot
Stereofly
Worth 4 dot
When the eyes are ABDUCTED, what muscles have the role of elevation and depression?
Rectus
When the eyes are ADDUCTED, what muscles have the role of depression and elevation?
Obliques
