eye anatomy Flashcards
The _______ is transparent and located at the anterior end of the eyeball.
The cornea is transparent and located at the anterior end of the eyeball.
The _____ reflex; when something touches or irritates the ______, it is sensed by the ______ nerve, a branch of cranial nerve ______. This sensory signal then reaches the ______ ______, and signals the ______ nerve, cranial nerve ______, to contract the ______ ______ to close our eyes.
Corneal reflex; when something touches or irritates the cornea, it is sensed by the ophthalmic nerve, a branch of cranial nerve V. This sensory signal then reaches the brain stem, and signals the facial nerve, cranial nerve VII, to contract the orbicularis oculi to close our eyes.
the _____ is opaque and makes the white shell of the eyes. It occupies the majority of the posterior eyeball and serves for attachment of the _____ muscles of the eye.
the sclera is opaque and makes the white shell of the eyes. It occupies the majority of the posterior eyeball and serves for attachment of the extrinsic muscles of the eye.
where the cornea and the sclera meet, is called the _________ junction.
where the cornea and the sclera meet, is called the corneoscleral junction.
the bigger posterior sphere is made of another two layers of tissue: the _______ layer that provides blood supply, located beneath the sclera; and the internal layer called the _____, that contains the photoreceptors and supporting cells.
the bigger posterior sphere is made of another two layers of tissue: the vascular layer that provides blood supply, located beneath the sclera; and the internal layer called the retina, that contains the photoreceptors and supporting cells.
The vascular layer, in turn, is made of three parts. From posterior to anterior, these are: the ____, the ____ body, and the ____.
The vascular layer, in turn, is made of three parts. From posterior to anterior, these are: the choroid, the ciliary body, and the iris.
What enters and exits eye at the optic disc?
What enters and exits eye at the optic disc?
Exit - Optic nerve, central and retinal vein
Entrance - Central retinal artery
Does optic disc contain photoreceptors?
Does optic disc contain photoreceptors?
no it is a blind spot
What does the macula specialise in?
“acuity of vision” without it every thing would be blurry - especially the fovea
what is the dot visible more laterally at the back of the eye. (not the optic disc)
Macula
What is the other name for the centre of the macula
fovea
Which structure of eye predominantly bends the light?
Cornea
Which structure of eye fine tunes the bending of the light?
lens
What are the boundaries of the anterior and posterior segments of the eye?
The anterior segment is between the cornea and the lens, and the posterior segment is found between the lens and the retina.
The anterior segment is further divided into an anterior chamber, between the _____ and the _____; and a posterior chamber, between the _____ and the _____.
The anterior segment is further divided into an anterior chamber, between the cornea and the iris; and a posterior chamber, between the iris and the lens.
The _____ humor is produced by the _____ _____ in the posterior chamber, and it flows through the _____ and into the anterior chamber.
The aqueous humor is produced by the ciliary processes in the posterior chamber, and it flows through the pupil and into the anterior chamber.
the aqueous humor is reabsorbed by the _____ _____ _____, (or the canal of _____), at the angle where the _____ meets the _____, called the _____ angle.
the aqueous humor is reabsorbed by the scleral venous sinus, or the canal of Schlemm, at the angle where the iris meets the cornea, called the iridocorneal angle.
the posterior segment, also called the _____ chamber, contains a more dense fluid called _____ humor, which is also transparent, and it provides support to the lens and holds the retina in place.
the posterior segment, also called the vitreous chamber, contains a more dense fluid called vitreous humor, which is also transparent, and it provides support to the lens and holds the retina in place.
The absence of ____________ stimulation, as well a potential inhibitory effect due to __________ innervation, causes the ciliary muscle to ______, ______ing the diameter of the ciliary body which __________(tenses/relaxes) the suspensory ligament so as to pull the lens in each direction. This results in __________(thinning/fattening) of the lens, which allows for (near/distant) objects to come into focus.
The absence of parasympathetic stimulation, as well a potential inhibitory effect due to sympathetic innervation, causes the ciliary muscle to relax, increasing the diameter of the ciliary body which tenses the suspensory ligament so as to pull the lens in each direction. This results in thinning of the lens, which allows for more distant objects to come into focus.
what are the muscles of the Iris and what do they do? (overall fx)
the iris allows us to see well either in a dark or light environment because it regulates the amount of light that passes through the pupil.
sphincter pupillae
dilator pupillae
when you leave a dark room for a light environment how does your iris adjust for light?
parasympathetic system signals the sphincter pupillae to contract the pupil, preventing excessive light from entering your retina
-
-
The eyeball is made of three layers:
the fibrous layer
the vascular layer
the inner layer, or retina
what nerve is responsible for corneal reflex
The ophthalmic nerve, a branch of CN V
, provides sensation to the cornea
. It is responsible for the sensory (afferent) limb of the corneal reflex
; when something touches or irritates the cornea
, it is sensed by the ophthalmic nerve.
what are the medial and lateral parts of your visual field named?
nasal and temporal
When light hits the retina it triggers ____ ____ ____ in the retina, called ____ and ____, to send an _________ _______
When light hits the retina it triggers visual receptor cells in the retina, called rods and cones, to send an electrical signal.
what is the blind spot of the retina
optic disc - the point where all the axons of ganglion cells are exiting the eyeball as cranial nerve II optic nerve
some visual axons cross the midline and some do not, which ones do?
Nasal portion of retina cross the midline, temporal axons do not
why do the optic nerves cross the midline?
allows organisation of sensory incoming information in line with the overlap of the visual fields
If you lose your left eye, what fields of vision do you lose and keep?
The Nasal portion of the left eye is still picked up by the right eye, but the peripheral vision is lost.
What path do the nerve axons take after exiting eye (to a nucleus)
optic disc > optic nerve > optic chiasm,
the axons of crossed and uncrossed fibers travel together as an optic tract synapse with cells in the lateral geniculate nucleus of each thalamus on both sides of the brain.
how does the brain recognise what you see as an image?
information travels
rods&cones > bipolar cells > ganglion cells > optic disc > optic nerve > optic chiasm > optic tract > lateral geniculate nucleus > optic radiations > primary visual cortex (occ lobe)
In primary visual cortex brain process the information and can assess form, colour, motion etc.
