The Eye Flashcards
structures of the eye
- eyebrow/eyelid/eyelashes
- conjunctiva
- lacrimal gland
- nasolacrimal duct
- extrinsic muscles of the eye
eyebrow/eyelash function
-protects eye from dust and foreign objects
eyelid function
-protects eye from foreign objects
eyebrow/eyelid/eyelashes function
- keeps eye moist
- contains a small amount of cartilage
conjunctiva structure
-thin mucus membrane
conjunctiva location
- on the inner surface (on the back part) of the eyelid and sclera
- doesn’t cover the cornea
sclera location
-white part of the anterior surface of the eyeball
conjunctivitis**
- pink eye
- can be inflamed and diffusely reddened sure to viral infection
lacrimal gland
- upper cornea of the orbit
- secretes tears with parth of flow
- ->upper lateral portion of eye to inferior medial part
what nerve controls the lacrimal gland?
-facial nerve (CN VII)
nasolacrimal duct
-passes from medial corner of the orbit and lateral nose to the nasal cavity
extrinsic muscles of the eye
- these muscles allow for superior, inferior, medial lateral rotational
- controlled by skeletal muscles
eyeball layers
- outermost
- middle
- innermost
outermost eye components
- sclera
- cornea
outermost eye: sclera location
- called the white of eye
- tough outermost layer of CT
- continuous with dura mater
outermost eye: sclera function
-protects the sensitive inner structure and gives shape
outermost eye: cornea location
- transparent anterior portion that bulges
- covers iris, pupils and anterior chamlar
is the cornea vascular or avascular?
- avascular
- oxygen diffuses from vessels in sclera
is the middle eye vascular or avascular?
vascular
middle eye components
- choroid
- ciliary body
- iris
middle eye: choroid function
-combines blood vessels supplying interior of eyeball
middle eye: ciliary body
-contains muscle which changes shape of the lens
middle eye: iris
- colored/pigmented smooth muscle
- regulates size of pupil to protect retina from strong light
what is the innermost eye called?
-retina (has 10 layers)
retina structure
- one outer pigment layer
- ->black in color which absorbs light rays
retina components
- pigmented layer
- nervous layer
retina pigmented layer
-only one layer
retina nervous layer
- nine layers
- 3 of them involved in conduction of image
which nervous layers are involved in the conduction of image?
- rods (dim light) and cones (color)
- bipolar cells
- ganglion cells
what are the steps in the visual response pathway?
- the stimulation of the photoreceptor cells of the retina(rods & cones) as light reached them
- impulses generated from retina are passed onto optic nerve and then to visual centers in cortex(occipital lobe)
optic nerve composition/location
- composed of axons from ganglion cell layer of retina (forms optic nerve and passes back towards brain)
- extends from posterior side of eye
optic nerve function
-transmits impulse to visual pathway
fovea centralis
-area of most acute vision/sharpest vision
optic disc
- aka “blind spot”
- where optic nerve enters with blood vessels
- no cells of retina here**
visual pathway path
retina–> optic nerve–> optic chiasm–> optic tract –> lateral geniculate (thalamus) –> optic radiations –> visual (occipital cortex)
lens
- changes shape to help bend light rays
- brings them into sharp focus on the retina
lens characteristics
- crystal clear/transparent
- contains elastic CT
- composed of protein
what is the len’s adaptability called?
-accomodation
what happens if there’s excess protein in the lens
- the lens becomes cloudy
- cloudy lens is called a cataract
cavities components
- anterior cavity (anterior to lens)
- posterior cavity (posterior to lens)
the anterior cavity is composed of what two chambers?
- anterior chamber
- posterior chamber
the anterior cavity’s chambers contain what?
-aqueous humor
aqueous humor
- a clear liquid produced by “ciliary body”
- continually produced
glaucoma
-if the aqueous humor isn’t drained through channels, the increases in pressure causes blindness (this is called glaucoma)
posterior cavity
- aka vitreous chamber
- contains vitreous humor
vitreous humor composition
-clear, gelatinous substance produced during embryonic development
vitreous humor function
-maintains pressure and shape of eyeball
how is the eye supplied with blood?
- vessels enter with optic nerve coming off branches of internal carotid artery
- vessels in choroid layer come in laterally
what needs to happen for optimum vision?
- light must be focused on the retina
- amount of light reaching retina must be regulated
- all controlled by ANS
what does the eye do for optimal vision?
- change in shape of lens (aka accommodation)
- alteration in size of lens
- convergence
accomodation overall functional components
- focuses on a far object
- focuses on a nearby object
how does the eye focus on a far object?
- ciliary muscles relax
- lens move back and stretched out by suspensory ligaments (bc lens is thin)
how does the eye focus on a close object?
- ciliary muscles tense up (get larger)
- lens move forward
what is convergence?
-eyeballs rotate medially for better focusing of light when viewing an object close up
altering size of pupils overall functional components
- dilation
- constriction
dilation
- muscle that runs radially (in smooth muscle)
- controlled by oculomotor nerve
constriction
- muscle turns in circular direction (in smooth muscle)
- controlled by oculomotor nerve
