eye structure Flashcards
what are the 6 extra ocular muscle of the eye ?
. superior oblique . inferior oblique . medial rectus . lateral rectus . inferior rectus . medial rectus
what are the skeletal muscle involved in blinking?
. orbicularis oculi - one of the facial muscles which runs around the eye
its contraction closes the palpebral aperture
. the levator palpebrae superioris - runs along the top of eye ball and sends tendons into eyelid
contraction raises the upper eyelid
why is there a lot of adipose tissue around the eye ?
. protection and acts as cushion and insulation
what does ora serrata represent ?
. it’s the junction between the ciliary body and retina
. junction marks the transition zone between simple non-photosensitive area of photoreceptor to multi-layered photosensitive retina
what type of tissue makes up vitreous humour ?
connective tissue made up of collagen and proteoglycan
what is the function of vitreous humour ?
. helps maintain the shape of the eye
. vital role in protecting the eye
. transmit light to retina
retina is involved in transduction - what is transduction ?
converts optical images into nervous potential
-turns photons of light into neurobiological activity.
what is the function of tapetum lucidum ?
it reflects visible light back through the retina , increasing the light available to photoreceptors .
. enhancing visual sensitivity
why is the tapetum lucidum unevenly distributed ?
its purpose is to reflect light to make image brighter so doesn’t have to be well placed
what is the area that appears black because there is no tapetum on the posterior surface of the eye ?
choroid
what is the function of the choroid ?
supplies the outer retina with nutrients
how is the lens attached to the ciliary body ?
by suspensory ligaments
which lens surface appears curved ?
cornea
why does the lens appear hard ?
because of chemicals , in living animals the lens is softer
what are the 3 layers of the lens ?
. an elastic capsule covering the entire surface
. a simple epithelium underneath this
. the bulk of the lens is made of elongated cells (lens fibres )
what pathological condition results in a loss of transparency ?
cataract
what is the ciliary body divided into ?
.anterior ridge pars plicata
. posterior , smooth , thinner pars plana
what are the ridges in the pars plicata made off ?
series of ridges known as ciliary process
what is the ciliary process covered ?
the ciliary process is covered by a 2 layered epithelium
. the pigmented epithelium - part of the eyes black box effect
.the un pigmented epithelium - produces aqueous humour
what is the structure of iris ?
its posterior surface is covered by 2 layered epithelium containing melanin.
this ensures that the only light that enters the eye is through the pupil
what is the function of ciliary body ?
. produces aqueous humour which supplies avascular cornea and lens with nutrients and oxygen
. ciliary muscle changes the shape of lens when your eyes focus near objects
how is aqueous humour drained ?
into the canal of schlemm at the filtration angle
what is the limbus ?
corneal scleral junction
what pathological condition results from inadequate drainage ?
glaucoma
What are the lens surtures?
The lens fibers that do not reach the poles form tight, interdigitating seams with neighboring fibers. These seams are readily visible and are termed sutures. The suture patterns become more complex as more layers of lens fibers are added to the outer portion of the lens.
What happens when you peel off the outer layers of the lens?
fibrous composion
loss of translucency
What is the lens nucleus?
The nucleus of the lens is made up of firm cortical substance, it is harder than the cortex because of its lower water content. There is no clear boundaries between the cortex and the nucleus of the lens.
What is the size of the cornea?
11.5mm
What is the cornea shape?
wider nasally.
What colour is the fat and muscle?
fat= white
muscle=brown
