Oculomotor Nerve [Important Notes] Flashcards
Two smooth muscles innervated by CN III?
sphincter/constrictor pupillae + ciliary body
Five skeletal muscles innervated by CN III?
levator palpebrae, inferior oblique and 3 rectus (superior, medial & inferior)
Three components of the near triad?
3 by CN III; convergence of eyes, pupillary constriction, contraction of ciliary muscle
Action of superior rectus muscle?
intorsion, adduction and elevation [turns pupil up and in]
Action of inferior rectus muscle?
extorsion, adduction and depression [turns pupil down and in]
Action of inferior oblique muscle?
extorsion, abduction and elevation [turns pupil up and out]
Muscle innervated by CN IV?
superior oblique
Action of muscle innervated by CN IV?
intorsion, abduction and depression [turns pupil down and out]
Action to test [isolate] muscle innervated by CN IV?
adduct and depress [in and then down]
Muscle innervated by CN VI?
lateral rectus
Action of lateral rectus muscle?
abducts eye
Action to test [isolate] the superior rectus muscle?
abduct + look up
Action to test [isolate] the inferior rectus muscle?
abduct + look down
Action to test [isolate] the inferior oblique muscle?
adduct + look up
What two extraocular muscles are used to look straight up?
superior rectus and inferior oblique
What two extraocular muscles are used to look straight down?
inferior rectus and superior oblique
Signs of compressive injury to CN III?
dilated pupil with normal eye movements
Aneurysm compressing CN III on what artery?
posterior communicating artery
Signs of diabetic infarct in CN III?
oculomotor palsy with normal pupil
Sign of injury to CN IV?
diplopia worse when walking down stairs; improves with head tilt to opposite side [Bielschowsky sign]
