Lab 8 - Special senses Flashcards
Peri visual info fall on what part of the retina
nasal retina
Medial visual field falls on what part of the retina
temporal retina
Lower VF pathway
upper retina upper LGN upper loop upper visual primary cortex
upper VF pathway
lower retina lower LGN lower loop lower visual primary cortex
lesion to the optic nerve
losing all of the info for that side (that eye)
lesion to the optic chasm
– lose the nasal retinal info, peri vision of both eyes
what is the optic tract carrying
all of the visual information for on VF
Left optic tract is carrying what info
carrying right visual field
what structure do we go to after the optic tract
LGN
two loops from the lGN
upper and lower
Lower (Myers) loop goes to what
lower visual cortex through the temporal lobe
upper loop goes throught what
upper primary visual cortex
Goes through the parietal lobe
when do central and peri vision separate
the cortex
Central visual cortex space
larger portion of the cortex
Peri vision cortex space
smaller portion of the cortex
Central vision sparing
Lesion – need to take out a large section of the cortex to take out central vision
this only happens at the level of the visual cortex, this that only place were central and peri are separate
left visual field of our LEFT eye projects onto what part of the retina
nasal part of the retina of the left eye
bottom of our visual field fall onto what part of the retina
top of the retina
Optic n lesion
Monocular
one eye is knock out
Optic chiasm lesion
Heteronymous hemianopsia (lesion 2)
‘bitemporal hemianopsia’
Taking out half of the VF for each eye – getting rid of peri vision
Optic tract lesion
Homonymous hemianopsia (lesion 3)
Loss of the VF (L or R) is lost from bot eyes
Optic radiation lesion
upper loop and lower loop
Homonymous quadrantnopsia (lesions 4)
parietal lobe – inferior quadrantnopsia
temporal lobe – superior quadrantnopsia (Meyer’s loop)
Occipital lobe lesion
Homonymous quandrantopsia with central vision spared
CN3 eye movements
up, down, in
up and in
CN4 - trochlear
down and in
CN6 - abducens
lateral eye movement
Lesion to CN 3 eye resting position
eye positioned more “out and down”
Lesion to CN 4 eye resting position
eye positioned more “up and out”
Lesion to CN 6 eye resting position
eye positioned more medially
medial longitudinal fasciculus (MLF)
‘highway’ for communication from abducens nucleus to contralateral oculomotor nucleus
What can elicit conjugate gaze?
- Voluntary tracking (vision and interest)via cerebral cortex – ‘smooth pursuit’
- Head movement: ‘semicircular canals’
- Moving object in the visual field: ‘optokinetic reflex’ (finding, tracking)
Vestibulo-ocular reflex –
efficient and quickly activated by vestibular apparatus; for stabilizing eyes for rapid turning or onset of head motion
*i.e.. turning head side-to-side while reading something
optokinetic reflex
finding, tracking
Moving object in the visual field
optokinetic reflex pathway
optic n optic tract a pretectal nuc medial vestibular nuc contralateral abducens nuc
what is faster optokinetic reflex or Vestibulo-ocular reflex
optokinetic reflex – slower effect than the vestibule-ocular reflex, but sustains stabilizing objects on the retina for longer duration of head movement; picks up when the vestibular system leaves off
dysconjugate gaze
two eyes don’t move together
dysconjugate gaze caused by a lesion to what
lesion of the MLF (dysconjugate but CN6 & CN3 function intact)
lesion of CN6, CN3, or occulomotor nucleus–(how do you differentiate?)
issue: Cranial nerve 6 (abducens) – move the eyes left
CBT
Direct response
constriction of the pupil ipsilateral to the pupil exposed to light
Consensual response
constriction of the pupil contralateral to the pupil exposed to light
horners syndrome symptoms
- persistent pupillary constriction
- ptosis of the upper eyelid
- loss of sweating on the involved side of face
horners syndrome cause
lesion of the sympathetic path to the head and neck)-break down of this pathway
