Ophthalmology Flashcards
what CN is the lacrimal gland supplied by
CN7 parasympathetic
facial
where is aqueous humour produced
in the ciliary body
how does aqueous humour get from posterior chamber to the anterior chamber
through the pupil via the trabecular meshwork into the canal of schlemm
where in the anterior chamber is the aqueous humour reabsorbed
the iridocorneal angle
the ophthalmic artery is a branch of which artery
the internal carotid
name 2 branches of the ophthalmic artery
central retinal artery
posterior ciliary artery
what is the central 2/3 of the retina supplied by
the central retinal artery
what is the outer 1/3 of retina supplied by
the posterior ciliary artery
where do your superior and inferior rectus muscles move your eye
superior rectus = up and in
inferior rectus = down and in
where do your superior and inferior obliques move your eye
superior oblique = down and out
inferior oblique = up and out
which muscle goes through the trochlear
superior oblique
innervated by the trochlear nerve (SO4)
where do medial and lateral recuts muscles move your eye
medially and laterally osly
what is code to remembering what nerve supplies what eye muscle
LR6 SO4 AO3
in the blink reflex, what nerve conducts the AP on the sensory (afferent) limb
CN V1 (ophthalmic) 1st branch of the trigeminal nerve
what are the 3 divisions of the trigeminal nerve
1 - ophthalmic
2 - maxillary
3 - mandibular
in the blink reflex, what nerve conducts the AP for the motor (efferent) limb and to which muscle
CN 7 (facial) to obicularis oculi
where do sympathetic axons exit the spinal chord
T1 -L2
eye autonomics
where does the presynaptic sympathetic axons synapse
in the superior cervical sympathetic ganglion
what structure do the post synaptic sympathetic axons ‘piggy back’ on
the internal and external carotid arteries
the ophthalmic artery carries the sympathetic fibres into orbit
where do parasympathetic axons leave the CNS
craniosacral outflow
leave CNS via CN 3,7,9 & 10
what are the long ciliary nerves supplied by
sympathetic
what are he short ciliary nerves supplied by
sympathetic and parasympathetic
what happens in sympathetic innervation of ciliary ganglion
eyes open wider
focus on far away objects
get more light into eye
emotional lacrimation
what happens in parasympathetic innervation of the ciliary ganglion
stimulates obicularis oculi - makes eye more closed
focuses on near objects
lets less light in
reflex lacrimation (to clean cornea)
what nerve supplies the afferent/sensory limb of papillary light reflex
CN 2 (optic)
what nerve supplies the efferent/motor limb of papillary light reflex
CN 3 (oculomotor)
what is the papillary light reflex
if you shine light into eye, it causes direct constriction of eye that light is being shone into and consensual constriction of the non-stimulated eye
in between what 2 neurones does the bilateral response in the papillary light reflex occur
between the 2nd and 3rd neurone
control of the lens
what happens in far vision
no parasympathetics ciliary muscle relaxes ligament tightens lens flattens focus on object in distance
control of the lens
what happens in near vision
parasympathetics ciliary muscle contracts ligament relaxes lens becomes spherical focus on near object
which CN carries the afferent/sensory limb of reflex tears
CN V1 (ophthalmic)
which CN carries the efferent/motor limb of reflex tears
parasympathetic CN 7 (facial
what is the vestibulooccular reflex
turns eyes in opposite direction of head movement
stabilises gaze during movement
CN III, IV, V3, VI
what is the oculo-cardial reflex
reflex bradycardia in response to tension in eye muscles or pressure on eyes
CNS connection between CN V1 & X
what is horner’s syndrome
impaired sympathetic innervation to head and neck
causes compression of cervical parts of sympathetic trunk
where is CSF produced
secretory epithelium of of choroid plexus in the ventricles
where does the choroid plexus come from
the 3rd, 4th and lateral ventricles
what does CSF secretion depend on
the active transport of Na+, Cl- & HCO3 from across epithelium from blood to CSF
explain the difference in ion levels between blood plasma and CSF
CSF has:
MORE Na and Cl
LESS K, glucose and protein
what are the names of the foramen that connect the ventricles
lateral to 3rd = intraventricular foramen
3rd to 4th = cerebral aqueduct
4th to subarachinoid space = foramen of magendie and foramina of luschka
how does CSF return from spinal chord to venous blood
via the arachinoid granulations into superior saggital sinus
describe the cellular structure of retina
from anterior to posterior
ganglion cells –> bipolar cells –> photoreceptors
what is the role of amacrine cells
receive input from bipolar cells
project it to ganglion and other bipolar cells
what is the role of horizontal cells
receive input from photoreceptor cells
project it to other photoreceptor and bipolar cells
explain the essence of phototransduction
photoreceptors have a depolarised resting membrane potential
with light exposure, the photoreceptor hyperpolarizes and turns OFF
basically, the presence of light causes the rod cells to hyperpolarize and turn off
what sort of channel is the ‘dark current’
a cGMP gated Na+ channel
open in the dark, closed in the light
the conversion of cGMP to GMP causes the cGMP Na+ channel to open. true?
nope - that conversion, using PDE as the enzyme, causes the cGMP channel to close
this causes the cell to hyperpolarize and turn rods OFF
light hits the rhodopsin in rod cells 1st. true?
yeh - it comes in and hits 11-cis-retinal in rhodopsin
this causes a conformational change to make it 11-TRANS- retinal
this causes transducin to break away from rhodopsin and bind to the PDE on the rod cell
what causes a reduction in the Ca+ and glutamate levels in phototransduction
hyperpolarization of the rod cell in light causes V-gated Ca+ channels to CLOSE
what does a reduced level of glutamate cause
causes depolarisation of ON CENTRE bipolar cells (activates
and
hyperpolarization of OFF CENTRE bipolar cells (deactivates)
what does activation of the on centre bipolar cells mean
the cone cells on the retina are being used to see
what are the 3 layers surrounding the brain called
the meninges
what’s the name of the 3 meninges
from outer to inner:
dura matter
arachinoid matter
Pia matter
which nerve is susceptible to compression and herniation as a result of raised ICP
CN 3 (occulomotor)
