Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
13 Cards in this Set
- Front
- Back
|
CN III, Oculomotor n. |
-- oculomotor nucleus (midbrain, ventral to periaqueductal gray) -> interpeduncular fossa -> lateral cavernous sinus => all extraocular mm., except for superior oblique & lateral rectus => levator palpebrae (elevator of the upper lid) -- Edinger-Westphal nucleus (b/w CN III nuclei) -> parasympathetic fibers -> ciliary ganglion => constrictor of the pupil & ciliary m. (constricts) |
|
|
CN IV, Trochlear n. |
-- trochlear nucleus - rostral pons (caudal midbrain; only CN exiting from dorsum of brainstem) -> decussates (as only CN; long & thin) -> ponto-mesenphalic jxn -> lateral cavernous sinus => superior oblique m. |
|
|
CN VI, Abducens n. |
-- abducens nucleus - caudal pons (facial colliculus, floor of the 4th ventricle) -> pontomedullary jxn -> dura, cavernous sinus => lateral rectus m. |
|
|
Saccadic eye movement |
= rapid eye movements to acquire new target (~ most voluntary eye movements; blurred during movement) - produced by CC or superior colliculus -> PPRF & rostral interstitial nuc. - resting tone baseline -> burst -> movement -> new resting baseline - delay ~200ms b/w burst & eye movement; head turns 20-40ms after -> vestibular fb -> opposite, compensatory eye movement - inhibited (/decrease from baseline) when moving in opposite direction - microsaccades: prevent image from blanching by fading on retina |
|
|
Horizontal conjugate gaze pwy |
= 1D saccadic eye movement: - R frontal eye field (A8, premotor C) (-> (R superior colliculus) -X-> L PPRF (paramedian pontine reticular formation) -> L CN VI --> L lateral rectus m. --> MLF -> R CN III -> R medial rectus m. [frontal eye field => contralateral gaze] |
|
|
Superior colliculus |
Afferents: retina, inferior colliculus, SC, CC Efferents: SC (tectospinal t.) & brainstem (tectoreticular t. - PPRF, midbrain RF) => adjusts head & eye towards a stimulus - visual field map representation - inward flow in information (visual -> motor l.) |
|
|
Internuclear opthalmoplegia |
- results from dmg to MLF b/w CN IV & III nuclei => eye moving laterally is NOT followed by medial movement of the other eye |
|
|
Vertical gaze pwy |
Diffuse CC A's -> rostral interstitial nucleus, MLF - rostral midbrain (vertical gaze center) -> upgaze: (-> posterior commissure) -> CN III, IV |
|
|
VOR (Vestibulo-Ocular Reflex) pwy |
- produces non-saccadic eye movements: CN VIII (-> Flocculus) -> Vestibular nucleus -> CN VI & PPRF -> MLF -> CN III, IV - used in compensation for head movement (& similar pwy: tracking a moving object) - when damaged => nystagmus (drift + saccade) |
|
|
Smooth pursuit/tracking pwy |
Occipital eye field (CC) (-> frontal eye field) -> pontine nuclei -> middle c. peduncle -X-> flocculus (contral.) -> inferior c. peduncle -X-> vestibular complex -/-> CN VI, PPRF (bilateral) -> MLF -> CN III, IV - stimulus = "retinal slip" - fixation & optokinetic reflexes (lost in movements towards a CC lesion) |
|
|
Vergence reflexes |
- focus on near objects - controlled by occipital cortex projections -> vergence center (RF, mesencephalon) - wired in parallel w/ accommodation (pupil, lens) |
|
|
Pupilary light reflex |
CN II -> pretectum (-> posterior commissure) -/-> Edinger-Westphal nucleus -> CN III -> pupillary constriction [consensual] |
|
|
Nystagmus |
- Pendular (symmetrical): not due to CNS/vestibular dmg - Jerk (fast & slow components) ~ vestibular system dmg / drugs & toxins -- slow ~ vestibular activity imbalance -- fast ~ compensation due to CC awareness - Horizontal: inner ear dmg - Down-beating: caudal brainstem dmg |
