Eyeball Flashcards
what is the eyeball?
a bilateral and spherical organ
what does the eyeball house?
houses the structures responsible for vision
where does the eyeball lie?
lies in a bony cavity within the facial skeleton – known as the bony orbit
anatomically, how can the eyeball be divided?
3 parts:
fibrous, vascular and inner layers.
what is the fibrous layer of the eyeball?
outermost layer
what does the fibrous layer of the eyeball consist of?
sclera and cornea, which are continuous with each other
function of sclera and cornea of fibrous layer?
provide shape to the eye and support the deeper structures
how much of the fibrous layer does the sclera make up?
comprises the majority of the fibrous layer (approximately 85%)
function of the sclera of fibrous layer?
It provides attachment to the extraocular muscles
function of extraocular muscles?
these muscles are responsible for the movement of the eye
what is the sclera seen as?
It is visible as the white part of the eye
describe the cornea (location)
transparent, and positioned centrally at the front of the eye
function of cornea?
Light entering the eye is refracted by the cornea
where is the vascular layer found?
The vascular layer of the eye lies underneath the fibrous layer
what does the vascular layer consist of?
choroid, ciliary body and iris
what is choroid within the vascular layer?
A layer of connective tissue and blood vessels
function of the choroid within the vascular layer?
It provides nourishment to the outer layers of the retina
what does the ciliary body consist of? (within vascular layer)
Comprised of two parts – the ciliary muscle and ciliary processes
what does the ciliary muscle consist of? (within vascular layer)
a collection of smooth muscles fibres
what are the ciliary muscles attached to? by? (within vascular layer)
to the lens of the eye by the ciliary processes
function of the ciliary body? (within vascular layer)
The ciliary body controls the shape of the lens, and also contributes to the formation of aqueous humor
what is the iris? (vascular layer of eye)
A circular structure, with an aperture in the centre (called the pupil)
what alters the diameter of the pupil? (vascular layer of eye)
smooth muscle fibres within the iris
what are the smooth muscle fibres within the iris innervated by? (vascular layer of eye)
the autonomic nervous system
where is the iris situated? (vascular layer of eye)
between the lens and the cornea
what does the inner layer of the eye consist of?
the retina
what is the retina? (inner layer of eye)
the light detecting part of the eye
what is the retina composed of? (inner layer of eye)
2 cellular layers:
Neural layer
Pigmented layer
what does the neural layer consist of? within retina (inner layer of eye)
Consists of photoreceptors; the light detecting cells of the retina
where is the neural layer located?
posteriorly and laterally in the eye
within retina (inner layer of eye)
where does the pigmented layer lie?
Lies underneath the neural layer
what is the pigmented layer attached to? (inner layer)
the choroid layer
CT of vascular - middle - layer
what is the function of the pigmented layer?
acts to support the neural layer
location of the pigmented layer?
continues around the whole inner surface of the eye
within retina in inner layer of eye
within the inner layer of the eye, which layer continues anteriorly? known as?
Anteriorly, the pigmented layer continues but the neural layer does not
known as the non visual retina
what is the optic part of the retina?
Posteriorly and laterally, both layers of the retina are present (neural + pigmented)
what can be viewed during ophthalmoscopy?
The optic part of the retina (posterior + lateral - both layers of retina)
what is the centre of the retina marked by?
marked by an area known as the macula
what is the appearance of the macula (centre of retina within inner layer)?
yellowish in colour, and highly pigmented
what does the macula contain? (centre of retina within inner layer)
a depression called the fovea
what does the fovea contain? (within macula, centre of retina within inner layer)
high concentration of light detecting cells
what is the fovea responsible for? (within macula, centre of retina within inner layer)
high acuity vision
what is the optic disc?
The area that the optic nerve enters the retina
what is significant about the optic disc?
it contains no light detecting cells
