The visual system Flashcards
List the following labels within the picture
1) iris
2) pupil
3) Conjunctiva ( lines eyelids and surface of eye)
Which 3 parts the eyeball can be divided into?
- Fibrous layers
- Vascular layers
- Inner layers
What is the fibrous layer?
outermost layer
consist of sclera and cornea
The function is to provide shape to the eye and support the deeper structures
What is a vascular layer?
layer underneath the fibrous layer,
consists of the choroid, ciliary body and iris
What is choroid and its function
The layer of connective tissue and blood vessels
- provides nourishment to the outer layers of the retina
What is a ciliary body and its function?
located between the choroid and iris
control the shape of the lens and contribute to the formation of aqueous humor
what is iris
aka pupil
Diameter of the pupil is altered by smooth muscle fibres –> sphincter pupillae <– control by the autonomic nervous system
sits between the lens and the cornea
what does the inner layer of the eye consist of?
retina
What technique does Optian use to check your eye?
ophthalmoscopy
What are the 2 main things you can see when an ophthalmoscope is used? (can use to image to help you out)
And what is their function?
Centre of the retina - macula
(its the dark area within the eye, the centre of the macula is called fovea)
*purpose –> highest concentration of light-detecting cells and area of high visual activity
optic disc –> area where the optic nerve enters
- it got no light-detecting cells in it
what is the condition of cataract?
Where there is a cloudy area in the lens of your eye
its a common condition through old age
what changes that shape of the lens
ciliary body
what are the two fluids that exist in the eye?
and where are they located?
anterior chambers
- located between the cornea and the iris
posterior chambers
- located between the iris and ciliary processes
what is the liquid that filled in the eye?
and function
aqueous humor
- nourishes and protects the eye
drains through the trabecular meshwork
what condition can be caused if the drainage of the aqueous humor is obstructed?
glaucoma
group of eye diseases that result in damage to the optic nerve
What are the 2 conditions of glaucoma?
Evaluate on cause and what will it lead to
Open-angle glaucoma
- the outflow of aqueous humor through the trabecular meshwork is reduced
- causes a gradual reduction of the peripheral vision
closed angle glaucoma
- iris is forced against the trabecular meshwork and prevents any drainage of aqueous humor
- lead to pressure buildup and changes in optic nerve –> lead to blindness
what are the 7 extrinsic muscle of the eye?
- superior rectus
- inferior rectus
- medial rectus
- lateral rectus
- superior oblique
- inferior oblique
- 1 levator palpebrae superioris muscle (controls the eyelid)
what is the attachments, action and innervation of levator palpebrae superioris?
attachments –> attaches to the superior tarsal plateof the upper eyelid
actions –> elevates the upper eyelid
innervation –> oculomotor nerve (CNIII)
where are the recti muscles originate from?
common tendinous ring
fibrous tissue at the back fo the orbit
Attachment, actions and innervation of superior rectus
A: superior and anterior aspect of the sclera
A: elevation, contributes to adduction and medial rotation of the eyeball
I: Oculomotor nerve (CNIII)
Attachment, actions and innervation of the inferior rectus
A: inferior part of the common tendinous ring, attaches to the inferior and anterior aspects of the sclera
A: depression (moving down), contributes to adduction and lateral rotation of the eyeball
I: Oculomotor nerve (CNIII)
Attachment, actions and innervation of medial rectus
A: medial part of the common tendinous ring
A: adducts the eyeball
I: Oculomotor nerve (CN III)
Attachment, actions and innervation of lateral rectus rectus
A: lateral part of the common tendinous ring
A: abducts the eyeball
I: Abducens nerve (CN VI)
oblique muscles originate from the common tendinous ring
True or false?
false, they have an angular approach to the eyeball and they attach to the posterior surface of the sclera
Attachment, actions and innervation of superior oblique
A: originates from the body of the sphenoid bone. The tendon passes through trochlea and attaches to the sclera of the eye posteriorly
A: depresses, abducts and medially rotates the eyeball
I:trochlear nerve (CN IV)
Attachment, actions and innervation of inferior oblique
A: originates from the anterior aspect of the orbital floor. attaches to the sclera of the eye posterior to the lateral rectus
A: elevates, abducts and laterally rotates the eyeball
I: Oculomotor nerve (CN III)
answer the following extraocular muscle action
Medial rectus -
lateral rectus -
superior rectus -
inferior rectus -
superior oblique -
inferior oblique -
Medial rectus - adduction
lateral rectus - abduction
superior rectus - elevation, adduction, medial rotation
inferior rectus - depression, adduction, lateral rotation
superior oblique - depression, abduction, medial rotation
inferior oblique - elevation, abduction, lateral rotation
states the nerve supply to the extraocular muscles
lateral rectus is 6th CN
superior oblique is 4th CN
rest are all 3rd CN
LR6-SO4-R3
What are the cranial nerves associated with innervation to the eye
Oculomotor nerve
trochlear nerve
abducent nerve
Answer the following numbers where does the oculomotor nerve branch off into?
1) superior rectus
2) levato palpabrae superioris
3) inferior oblique
4) medial rectus
5) inerior rectus
6) ciliary ganglion
7) short ciliary nerves
what are the 2 structure sin teh eye that receive parasympathetic innervation from the oculomotor nerve?
sphincter pupillae
- constricts the pupil and reduces the amount of light entering the eye
ciliary muscles
- contracts which cause the lens to become more spherical and thus more adapted to the short-range vision
How does the trochlear nerve innervate the superior oblique muscle?
- emerges from the posterior aspect of the midbrain
- exits the superior orbital fissure and enters into the orbit
What function does the abducens nerve have and what muscle does it innervate?
only somatic motor function
innervation to the lateral rectus muscle
Describe optic nerve and function
- 2nd cranial nerve and responsible for transmitting sensory information for vision.
detailed version v
transmission of special sensory information from the retina of the eye to the primary visual cortex of the brain.
optic nerve is surrounded by________?
cranial meninges
which 2 components are divided from the primary visual cortex of the brain?
extracranial
intracranial
where is the optic nerve formed from in the extracranial? and function?
retinal ganglion cells
receive impulses from the photoreceptors fo the eye
pathway of extracranial
the nerve leaves into the optic canal and through the sphenoid bone, and along the surface of the middle cranial fossa
what does optic nerves forms into in the intracranial
optic chiasm
What fibres do the left optic tract contain?
Contain
- left temporal (lateral) retina
- right nasal (medial) retina
What fibres do the right optic tract contain?
- right temporal retina
- left nasal retina
Where will the optic tract travel to, which locates in the thalamus?
lateral geniculate nucleus (LGN)
How do our eyes see stuff? Evaluate the overview of the visual pathway.
signal of the vision travel to the optic disc
v
travels through the optic nerve and to the optic chiasm
v
then travels to the lateral geniculate nucleus (LGN) through the optic tract
v
Finally travel to the Primary visual cortex by the topic radiation
