Flashcards in Ocular Anatomy / Physiology Deck (91)
a CN X lesion will have what effect in the mouth? How does this compare to a CN XII lesion?
CN X: Uvula will pull away from side of lesion
CN XII: Tongue pushes towards the side of lesion
What are the three possible destinations for a ganglion nerve fiber coursing through the optic nerve? What do these destinations control?
LGN: Primary visual cortex
Superior Colliculus: Saccades
Pretectal Nucleus: Pupils
What does CN I control?
What does CN II control?
What does CN III control?
EOMS (superior rectus, inferior rectus, inferior oblique, medial rectus)
What does CN IV control?
What does CN V control?
What does CN VI control?
What does CN VII control?
Anterior 2/3 taste
Salivation (Submaxillary, Submandibular)
What does CN VIII control?
What does CN IX control?
Posterior 1/3 taste
Monitor carotid sinus
What does CN X control?
What does CN XI control?
What does CN XII control?
The medial longitudinal fasciculus connects what four cranial nerves?
CN III, CN IV, CN VI, CN VIII
What sub-nucleus of CN III decussates to innervate the contralateral muscle?
Sub-nuclei for IR, IO, and MR go to ipsilateral muscle
What is unique about the levator sub-nucleus?
There is only ONE sub-nucleus for BOTH levators
What are the divisions of the CN III?
Superior - Superior Rectus and Levator, Sympathetic fibers (Muller's muscle)
Inferior - Inferior Rectus, Inferior Oblique, Medial Rectus
What structures do the fibers of CN III travel with as they course from the sub-nuclei to their respective muscles?
Sub-nuclei in Brainstem -> PCOM Artery -> Cavernous Sinus -> Superior Orbital Fissure
Where do sympathetic fibers join CN III? Where do they come from? What division of CN III do they join?
Superior division of CN III receives sympathetic fibers from the ICA in the cavernous sinus
Where do parasympathetic fibers join CN III? Where do they come from? What division of CN III do they join?
Inferior division of CN III receives parasympathetic fibers from the EW nucleus
What would happen to the eye in a complete CN III palsy?
Severe ptosis. Eye would be DOWN and OUT.
Pupil involved CN III palsy is most likely due to ______. Pupil-sparing CN III palsy is most likely due to ______.
Pupil-involving CN III palsy -> PCOM and ICA junction (tumor / aneurysm)
Pupil-spring CN III palsy -> Microvascular ischemia (DM / HTN)
What is unique about the course of CN IV?
Exits DORSALLY from the midbrain (at the level of the inferior colliculus) and decussates to innervate the CONTRA superior oblique
The ______ connects the sub-nucleus of CN IV to the visual cortex through the _________
The *tectobulbar tract* connects the sub-nucleus of CN IV to the visual cortex through the *superior colliculus*
Damage to the LEFT CN IV sub-nucleus will cause a _____ superior oblique palsy and _____ head tilt
Damage to the LEFT CN IV sub-nucleus will cause a *RIGHT* superior oblique palsy and *LEFT* head tilt
The anatomical origin of the superior oblique is the _______, the physiological origin is the _______
Anatomical origin - lesser wing of sphenoid
Physiological origin - trochlea
What is the Arden Ratio? What value is considered normal?
EOG measurement of the differences in the RPE response under light and dark conditions
normal Arden Value = Greater than 1.80
What do the waves of an ERG correspond to?
B-wave: Bipolar and Amacrine cells