Flashcards in Eye Anatomy Deck (148)
What are the parts of the fibrous coat of the eyeball?
Sclera & cornea
What are the parts of the vascular coat of the eyeball?
What are the parts of the sensory coat of the eyeball?
What is the function of the sclera?
Gives attachments to the extrocular muscles
How much of the fibrous coat does the sclera make up?
What is the function of the cornea?
Allows light to enter the eye
How much of the fibrous coat does the cornea make up?
What is the function of the choroid?
Supplies blood to outer layer of retina
What is the function of ciliary bodies?
Produces Aqueous humor
Suspends the lens
What is the function of the iris?
Controls the diameter of the pupil & therefore the amount of light entering the eye
What is the function of the retina?
Has rods & cones which enable us to see
Where is vitreous humor found?
Where is AH found?
What is the structure of the lens described as?
Biconvex crystalline structure that is suspended from the ciliary body by suspensory ligaments
What is the function of the AH?
It maintains intraocular pressure
What is the function of VH?
Cushions the retina
What is the anterior segment further divided into?
Anterior & posterior chamber
Where is the Anterior chamber found?
In front of the iris
Where is the anterior segment found?
In front of the lens
Where is the posterior chamber found?
Behind the iris
Where is the posterior segment found?
Behind the lens
At the angle of the anterior chamber where does AH drain?
Via trabecular meshwork into the Schlemms canal
What are the names of the 3 entry/exit points in the bony orbit?
Superior orbital fissure
Inferior orbital fissure
Which paranasal sinuses is the orbit closely related to?
Which area of the orbit is the weakest?
Medial & inferior walls of the orbit
What cushions the eyeball in the orbit?
What is another name for the mucosa membrane on the inside of the eyelid?
What type of gland is associated with eyelashes?
What muscle is responsible for elevating the eyelid?
Levator palpebrae superioris
What is the name of the hard plate found in the eye lid?
What is the name of the glands found in association with the tarsal plate in the eyelid which produce oily secretions?
What are the different areas of the conjuntiva called?
Superior/ Inferior fornix
What does the ocular conjunctiva cover?
Which nerve stimulates the lacrimal gland?
Facial nerve (parasympathetic)
Where do tears drain from the eyeball?
Via punctate in the medial side of eye into lacrimal sac
Where do tears drain from the lacrimal sac?
Where does the nasolacrimal duct drain?
What do intrinsic muscles of the eye control?
Pupil diameter & regulate lens curvature
What do extra ocular muscles control?
The movement of the eyeball
What muscle constricts the iris? What innervation?
Constrictor pupillae (circular)
Parasympathetic - IIIn
What muscle dilates the iris? What innervation?
Dilator pupillae (radial)
What innervates the ciliary body muscles?
When the ciliary bodies are activated what happens to the structure of the lens? What is this called?
Thicker & rounded
Focus close up
How many straight muscle (recti) are found in the eye orbit?
4 - SR, LR, MR, IR
How many oblique muscles are there?
2 - SO, IO
Where do the recti muscles arise/insert?
Apex of orbit from annular fibrous ring & insert anteriorly to sclera
Where does the SO arise/insert?
Roof of orbit & insert posteriorly to sclera
Where does the IO arise/insert?
Floor of orbit anteriorly & insert posteriorly
What nerve supplies the LR?
Abducent nerve (VI)
What nerve supplies the SO?
Trochlear nerve (IV)
What nerve supplies the IO
Oculomotor nerve (III)
Where do parasympathetic fibres carried by IIIn synapse?
Which nerve carries sensory information to the orbit?
Trigeminal nerve (V1 & 2)
Where dos the maxillary division of trigeminal exit onto the face?
What is the ophthalmic artery a branch of?
What branch of the ophthalmic artery travels within the optic nerve?
Central retinal artery
What is another name for the physiological blind spot?
What is the name of the area of retina which has a high density of cones?
What are the 4 divisions the retina is divided into?
Where do the superior & inferior ophthalmic veins drain into?
Which germ layer do eyes originate?
Ectoderm (from neural tube)
Where do optic vesicles grow out from?
Diencephalic part of neural tube
What forms after the optic vesicle in embryonic development of eye?
What embryological layer forms the EOM?
What epithelial layer is found at the cornea?
Stratified squamous non-keratinised epithelium
What is another name for the basement membrane at the corneal epithelium?
What is the thickest layer in the cornea called?
What is the stroma of the cornea composed of?
Regularly arranged collagen
How many histological layers are present at the cornea?
What factors contribute to the cornea being transparent?
Regularly arranged collagen fibres in stroma
No blood vessles
Endothelial layer has pump which keeps AH out
Why does the avascularity of the cornea contribute to effective corneal transplants?
Less risk of rejection
How many layers compose the retina?
What is the 1st layer of the retina composed of?
What is the 2nd retinal layer composed of?
Rods & cones
What is lens opacification called?
What are the functions of the tear film?
Keeps cornea moist
Washes away particles of foreign body
Smooths outer layer of cornea for refraction
Clinically how can you visualise the tear film?
Staining with fluorescein
How many layers compose the tear film?
1: mucinous layer
2: aqueous layer
3: oily layer
Which muscles elevate/depress the eye when it is adducted?
Which muscles elevate/depress the eye when it is abducted?
What is the mnemonic used to remember EOM movements?
What are the actions of the SR?
What are the actions of the IR?
What are the actions of the SO?
What are the actions of the IO?
What is the clinical term for squint?
What is the name of a convergent squint?
What is the name of a divergent squint?
What is amblyopia?
A lazy eye caused as a result of squint left uncorrected leading to suppression of image
What are the functional consequences of a squint?
When there is an increase in illumination, what happens to the pupil?
Constricts via IIIn parasympathetic fibres
When there is an decrease in illumination, what happens to the pupil?
Dilates via sympathetic innnervation
In a pupillary reflex, what are the names of the responses you are looking for?
What is the term used to describe pupils of different sizes? In what condition is this seen?
eg Horners syndrome
In the pupillary reflex, does light go to the LGB & visual cortex?
No, it goes to the midbrain to the Edinger-Westphall nucleus (part of IIIn nucleus)
In the pupillary reflex, where do afferent fibres go from the EWN?
Preganglionic fibres pass through orbit via IIIn & synapse in ciliary ganglion.
Postganglionic fibres inveiate constrictor pupillae = PUPIL CONSTRICTION
What eye related condition is associated with MS?
What type of conditions can impair pupillary reflex?
What disease can cause damage to IIIn however parasympathetic fibres are spared?
What are the clinical signs of Horners syndrome?
Where do postganglionic sympathetic fibres travel?
Along blood vessels
Name a cause of Horners syndrome & what is its pathology
Loss of sympathetic innervation to the head
Pancoast lung tumour
What components of the eye are responsible for bending light?
What is another term for the bending of light?
When an object is close up, what happens to the shape of the lens? Why?
Lens becomes thicker
Light has to bend further in order to focus on retina
What part of the eye is the most powerful bender of light?
The focusing capacity of the eye changes from distant to close object, is called?
What are the 3 changes occur when the eye accommodates?
Lens becomes thicker & spherical
When the ciliary muscles contract, what happens to the lens?
Thicker & spherical
(suspensory ligaments become lax)
What innervation causes contraction of ciliary muscles?
What EOM do we use in order to converge eyes in accomdation?
What is the clinical term for shortsightedness?
In myopia, where does the light refract?
In front of the retina
If someone has myopia, what is there vision like?
Hazy in distance
Clear close up
If someone has emmetropia, what is there vision like?
What are some of the symptoms of myopia?
Headaches, unable to see blackboard
In infants = divergent squint
How can myopia be treated?
Reduce the bending power of lens by:
Laser eye surgery
What is the clinical term for farsightedness?
If someone has hyperopia, what is there vision like?
Hazy close up
Distant is clear
Why might someone suffer from hyperopia?
Eyeball too short
Lens too flat
Where is the image formed in the eye in hyperopia?
Behind the retina
What are some of the symptoms associated with hyperopia?
Eyestrain after reading
What can you use to treat hyperopia?
Laser eye surgery
Where is the light focussed when a person has astigmatismsm?
Will not be refracted into one area on retina
Describe the pathology of astigmatisms
Les appears oval shaped resulting in light being bent differently
What will someones vision with astigmatism be like?
Hazy for close & distant vision
Ho can you treat astigmatism?
Laser eye surgery
Special spectacles - cylindrical glasses
Contact lens - topic lenses
What is longsightedness in older age called?
Why does presbyopia occur in older age?
Lens becomes less mobile therefore when ciliary muscles contract, lens less able to change shape
How can presbyopia be treated?
Where are photoreceptors found?
Defined as a conversion of light energy to electrochemical response by photoreceptors
Which vitamin is associated with phototransduction? What is its role?
Vitamin A (retinol)
Visual pigment regeneration
What are the 2 types of photoreceptor found in the retina?
Rods & cones
What is the main visual pigment found in the eye?
What is the main source of vitamin A?
If there is vitamin A deficiency, what will be clinical signs?
In what conditions can vitamin A dificiency occur?
Malabsorption disease - coeliac disease
What are some clinical signs of vitamin A defiency observed in the eye?
Bitots spots in conjunctiva
Opacification of cornea (silver spots)
What is the visual field defined as?
Everything you can see in ONE eye (including periphery)
Where is maximal visual acuity achieved?
What is absent at the optic nerve head?
Rods & cones
Which fibres cross at the optic chiasm?
Where do fibres from optic tract synapse?
Where is the LGB found?
In the visual cortex, which visual field does the left side of the brain perceive?
Right visual field
If the optic tract or optic radiation is damaged, what will happen to visual field?
Contralateral homonymous hemianopia