ANATOMY Flashcards
white part of eye?
sclera = POSTERIOR 5/6
3 layers of eye? order
out fibrous coat vascular coat sensory coat in
iris part of eye gives what?
function
coloured part of eye
controls diameter of pupil
and controls amount of light entering eyeball
3 parts of vascular part?
ciliary body
iris
choroid
cornea?
anterior 1/6 of eye which is transparent and allows light into eyeball
choroid function?
supplies blood to outer layers of retina by diffusion
what does retina contain?
has light sensitive rods and cones which enables us to see
what is lens suspended by and from what?
suspended by suspensory ligaments from ciliary body
purpose of aqueous humour?
maintains intraocular pressure
prrpose of vitreous humour?
helps cushion the retina
chamber of anterior segment?
anterior chamber - in front of iris
posterior chamber - behind iris but infront of lens
how does AH flow?
from posterior chamber to anterior chamber
through angle of anterior chamber and trabecular meshwork
and then through schlemms canal
what glands present on eyelashes?
sebaceous glands
conjunctivae?
what does it not cover?
thin vascular membrane that covers inner surface of eyelids and loops back over sclera
not covering cornea
lacrimal gland?
innervation
situated in orbit laterally
parasympathetic from facial nerve
innervation of ciliaris?
parasympathetic - constrict
innervation of dilator papillae?
sympathetic
position of oblique muscles of eye?
superior - from roof of orbit posteriorly
inferior - floor of orbit anteriorly
how do the recti and oblique muscles insert onto eye?
recti - anteriorly onto sclera
oblique - posteriorly onto sclera
extra muscle of eye called?
LPS - lever palpebrae superioris
innervation of eye muscles?
SO - trochlear nerve
LR - abducent nerve
everything else - occulomotor
optic nerve of eye does what?
carries visual impulse from eyeball to brain etc
oculomotor nerve of eye?
fibers type
pathway?
innervates all eye muscles except two and carries parasympathetic fibers
flows to synapse at ciliary ganglion in orbit
what artery supplies orbit?
ophthalmic artery branch of ICA
central retinal artery?
branch of ophthalmic artery - supplies inner layers of retina
short posterior ciliary arteries?
branches of ophthalmic artery - supply posterior part of choroid and outer retina
long posterior ciliary arteries?
branches of ophthalmic artery - supply anterior part of choroid, ciliary body, iris
innervation of eye includeS?
sensory
motor
autonomic
sensory innervation of eye by?
CN V1
any blood vessels in cornea?
no vascularity here
name of basement membranes in cornea?
bowman
descemets
cornea transplant why is avascularity key?
rejection of transplant is unlikely - less matching is needed here
glaucoma?
where angle is closed and AH not drained and intraocular pressure increases in eye leading to blindness
fovea centralis?
cones and no rods
packed with cones and so max visual acuity
centre part of fovea
cataract is opacification where?
on LENS
macula?
more cones than rods
function of tears?
keeps cornea moist
washes away foreign bodies
provides smooth surface for refraction of light
3 layers of tear film?
inner/deep - mucinous layer
aqueous layer - water
outer/superifical - oily layer
blinking does what to tear film?
distributes tear filme evenly
what happens to tear film with eyes open?
and triggers to blink
aqueous component of tears begin to evaporate and oily layer is getting closer to the mutinous layer
when these 2 layers touch it triggers to blink
how does light move in eye?
light waves bend at cornea but more so at lens to form clear image on retina
close up objects therefore?
lens
lens is thicker and constricts more
as need to bend light more
accommodation of eye?
ability to focus on far off or near objects by changing how much we need to bend light
what causes lens to contract?
innervated by?
ciliary body contraction
by parasympathetic innervation
makes lens thicker
what happens to eyes when close up object?
converge
name all extrinsic muscles of eye?
MEDIAL RECTUS LATERAL RECTUS INFERIOR RECTUS SUPERIOR RECTUS SUPERIOR OBLIQUE INFERIOR OBLIQUE
MYOPIA?
explain issue
treatment
short -sight
see close up not far off
-2/-3 etc
rays focus before retina - bending power too much
use of biconcave lens to correct and reduce bending power
hyperopia?
explain issue
treatment
long sighted
see far off not close up
+2/+3
rays formed behind retina
use of biconvex lens to elevate bending power
convergent squint in person means?
hyperopia
astigmatism?
explain physiology
treatment
close up and far off are hazy
due to surface having different curvature in different areas
cylindrical glasses - one curve on axis
measured in degrees & numbers seperetaly
what in the eye generates AP?
rods and cones triggered by visible light
lamellae of rods contain?
visual pigment rhodopsin in the cell membrane
lamellae of cones contain?
cone OSPINS O, M, L
WHICH DIFFER IN THEIR SPECTRAL SENSITIVITY
HOW DOES LIGHT ONTO visual pigments in the rods and cones result in action potential?
1.light onto rods/cones
2.opsin protein in them have vitamin A structure called 11 cis retinal
3. it is converted to all-trans retinal
cell changes shape
all-trans retinal bleaches pigment
lead to hyperpolaristaion
and impulse transmitted and ap created
phototrasnduction?
where light is converted into electrical impulses
role of vitamin A in the visual pigment?
visual pigment regeneration - RECYCLE OF CIS RETINOL - to reform opsin
vitamin A deficiency?
will affect vision
needed for healthy epithelium
vitamin A deficiency signs?
triangle spots in conjunctivae
corneal ulcers
where is trans-retinol converted into cis retinol?
in RPE -
visual field test?
use of finger to test fuel of vision
visual acuity test?
use of snellens chart
how do fibres run in the eye?
- from eye through optic nerve
- through optic chiasma
- medial fibers cross here to opposite side
- through optic tract
- synapse at LGB of thalamus
- from here optic radiation to reach primary visual cortex in occipital lobe
optic chiasma lesion lead to?
bitemporal hemianopia
optic tract/radiation lesion lead to?
contralateral homonymous hemianopia
