Neuro-Opthamology Flashcards
There are conventionally ____ pairs of cranial nerves
12
With the exception of CNs ___________ , all nuclei are present in the ___________.
I and II
Brain stem
Location of the Nucleus : Cranial Nerves
Base of the Fore brain
Midbrain
Pons
Medulla
CN I, CNII
CN III, CN IV
CNV, CNVI, CN VII, CN VIII
CN IX, CN X, CN XI, CN XII
Optic nerve
It carries approximately ________ afferent fibres which originate from the ____________________.
Most synapse in the _________________
1.2 million
Retinal Ganglion Cells(RGCs)
Lateral Geniculate Body(LGB).
The optic nerve fibres are divided into about _________ bundles by fibrous septae derived from the ________
600; pia mater
Optic nerve
Nearly ________ of the fibres subserve the central 5 degrees of the visual field.
The optic nerve is approximately ______ long from the globe to chiasm.
Divided into 4 segments: _____,_____,______,_______
one-third
50mm
Intraocular
Intraorbital Intracanalicular Intracranial
VISUAL PATHWAY
List them
Optic nerves
Optic Chiasma
Optic tracts
Lateral geniculate bodies\ Optic radiations
Occipital cortex
Anatomy of the visual pathway
From the chiasm, the visual pathway continues into the __________
Fibres in the optic tracts synapse in the _______________ (above or below?) the ___________
The pathway continues in the _________ to the ________________
Visual defects from now on affect the same side of vision in both eyes and are therefore homonymous
optic tracts
lateral geniculate body; below
thalamus; visual radiations
occipital cortex
Pupillary pathways
________ reflex
_______ reflex
Pupillary _________
Psychosensory reflex
Light
Near
dilatation
Light reflex pathway
1.AFFERENT PATHWAY
The _______ segment of the ______________ are the receptors for both visual pathway and light reflex.
2)EFFERENT PATHWAY: Preganglionic parasympathetic myelinated fibres go to the _____________ via CN ______ .
The postganglionic myelinated fibres pass through __________ nerves to innervate the __________ pupillae.
outer; rods and cones
ciliary ganglion ; III
short ciliary; sphincter
Near Reflex Pathway
Near reflex occurs on looking at a near object.
Near reflex triad : ___________,__________ and _____________
accommodation, convergence and constriction.
Near Reflex Pathway
Convergence reflex comprises of convergence of the __________ of the eyes with associated _______________.
Consists of the afferent pathway which begins at the _________ and the efferent pathway which is similar to that of the ______________
visual axes
constriction of the pupil
medial recti
efferent light reflex
Pupillary dilatation pathway
______pathetic pathway and begins in the ____________________.
sym
posterior hypothalamus
Causes of Lesions of the visual pathway
List 5
Trauma
Tumour
Vascular lesion
Inflammation
Degeneration
Damage to the oculomotor nerve (III) can cause _______ vision and inability to coordinate the movements of both eyes (__________), also ______________ and _________________.
Lesions may also lead to inability to open the eye due to ________________
double; strabismus
eyelid drooping (ptosis) and pupil dilation (mydriasis)
paralysis of the levator palpebrae muscle.
Individuals suffering from a lesion to the oculomotor nerve may compensate by _______________ to alleviate symptoms due to paralysis of one or more of the eye muscles it controls
tilting their heads
Damage to the trochlear nerve (IV) can also cause double vision with the eye _______ and ____________. The result will be an eye which can not move ______wards properly (especially ______wards when in an _________ position). This is due to impairment in the superior oblique muscle
adducted; elevated
down; down
inward
AMAUROTIC PUPIL
______________ pupillary defect.
Caused by a ________________________ or _____ lesion leading to _________ on the affected side.
The VA is _________.
Total afferent
complete optic nerve or retinal
total blindness
NPL
AMAUROTIC PUPIL
Affected pupil neither _____________ nor does it _________________________, however it has a good consensual light reflex from stimulation of the contralateral eye.
Afferent = ______. Efferent = ________
reacts to a direct light
create a consensual pupillary light reflex
lesion; normal
MARCUS GUNN PUPIL
____________ pupillary defect.
Best tested by _______________ test.
A paradoxical response whereby the affected pupil dilates when _________________________________ .
Relative afferent
swinging flash light
light is moved from the normal eye to the abnormal eye
MARCUS GUNN PUPIL
Grades :
1=______ constriction and ______ redilatation.
2= _________ and _______ redilatation
3= __________ dilatation
4= ______________ dilatation following ______________________
5= ___________ dilatation with _____________ constriction at all.
weak; greater
initial stall and greater
immediate
immediate pupillary; illumination of good eye for 6 seconds.
immediate; no secondary
WERNICKE’S HEMIANOPIC PUPIL
Indicates a lesion in the ________.
Light reflex is absent when light is thrown on the __________ half of the retina of affected eye and the ________ part of the retina on the unaffected eye.
Patient also has _____________
optic tract
temporal; nasal
homonymous hemianopia.
ARGYLL ROBERTSON PUPIL
Classical finding in __________
Mostly seen in people with Tabes dorsalis i.e. syphilitic myelopathy – demyelination of nerves primarily in dorsal column of spinal cord.
neurosyphilis
ARGYLL ROBERTSON PUPIL
Lesion in the region of the _______________, ________ area and rostral midbrain dorsal to the _____________ where there is also disturbance of the normal inhibitory pathways from the reticular activating system upon the parasympathetic EW subnucleus.
Other causes include diabetes, midbrain lesions.
aqueduct of sylvius
pretectal; EW nucleus
TONIC PUPIL (Adie’s pupil)
Light-near dissociation; near accommodation produces more ________ compared to ______________.
Damage to the parasympathetic __________ or ______________ denervation supersensitivity of iris sphincter whereby postsynaptic receptors are upregulated to aid reinnervation aberrant reinnervation with fibres intended for ciliary body targeting the pupil light-near dissociation.
Notable syndromes associated with tonic pupil include Holmes-Adies syndrome, Ross syndrome, Riley Day syndrome
miosis; response to light
ciliary ganglion; short ciliary nerves
HORNER’S SYNDROME
Lesion of the sympathetic system characterized by ________,____________, and _______________ on the affected side.
miosis, partial ptosis and anhydrosis
HORNER’s Syndrome
Ptosis- mild or moderate, due to _________________.
Miosis- moderate miosis with dilatation lag, due to _________________
Facial anhydrosis-____________ on ipsilateral face and neck, usually occurring in the preganglionic type.
Heterochromia iridis can occur in congenital Horner’s syndrome where ________________________ fail to develop.
paralysis of Muller’s muscle
unopposed action of the sphincter pupillae following paralysis of the sympathetically innervated dilator pathway.
reduced sweating
iris pigment of the stroma
