Intro to nervous system + anatomy of eye Flashcards by RC RC

Name the 3 layers of the eye

Fibrous layer
Vascular layer (uvea)
Sensory layer

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What does the fibrous layer of the eye consist of (2)

Sclera (posterior 5/6) + cornea (anterior 1/6)

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What does the vascular layer of the eye consist of (3)

Choroid, ciliary body + iris

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What does the sensory layer of the eye consist of (1)

Retina

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Function of sclera

extrinsic ocular muscles attach to it

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Function of cornea

transparent window to allow light rays into eyeball

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Function of choroid

Made up of fenestrated blood vessels which supply blood to OUTER LAYERS OF RETINA by diffusion

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What is the blood supply to the inner layers of the retina

central retinal artery

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Function of ciliary body

Suspends the lens via suspensory ligaments (zonules)

Produces aqueous humor

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Function of ciliaris

contracts to change shape of the lens and allow accommodation

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Function of iris

Controls the diameter of the pupil by concentric and radial muscles and thereby control the amount of light rays entering eye

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Retina function

Contains photosensitive rods and cones to allow us to see

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How many layers does the retina consist of

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What is the

1st layer of the retina (furthest back)
2nd layer of the retina
9th layer of the retina

Pigment epithelial layer
Rods and cones layer
Nerve fibre layer

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Function of the pigment epithelial layer of the retina

Maintains health of the rods and cones

Contains pigments which absorb and help vitamin A recirculation

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What does the nerve fibre layer of the retina contain

axons which join to form the OPTIC NERVE

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How is the retina made more efficient

Fovea centralis

-exposed at surface of retina and PACKED WITH CONES to MAXIMISE VISUAL ACUITY

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AH produced by what

Ciliary body

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AH secreted where first

Posterior chamber

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Where is AH drained out of the eye

angle of the anterior chamber

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AH drainage apparatus consists of what

Trabecular meshwork (Acts like a sieve) –> schlemm’s canal

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Shape of lens + what is it suspended by

Biconvex

Zonules from ciliary body

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How is the lens transparent

Due to regular arrangement of collagen fibres and avascularity

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Lens opacification leads to formation of a …

cataract

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Bony orbit is closely related to ethmoidal and maxillary sinuses so what walls of the orbit are weak (2)

Medial & inferior

Anterior posterior length of eyeball Anterior posterior length of orbit

24mm 40mm, because orbital fat cushions the eyeball posteriorly

What opening does CN III enter the orbit

Superior orbital fissure

CN III innervates LPS + all extrinsic eye muscles except which 2

Superior oblique Lateral rectus

CN IV enters the orbit via which opening

Superior orbital fissure

CN VI enters the orbit via which opening

Superior orbital fissure

CN V1 enters orbit via which opening

Superior orbital fissure

CN V2 enters orbit via which opening

Foramen rotunda

What is the general sensory innervation to orbit and eye (2)

CN V1 & V2

Largest branch of CN V1 within the orbit

Frontal nerve branch

Name some small branches of CN V1 within the orbit (2)

Nasociliary nerve branch | Lacrimal nerve branch

Branches of CN V2 innervate what (2)

Floor of orbit | Lower eyelids

Function of intrinsic muscles of the eye

control pupil diameter & changes shape of lens

Function of extrinsic muscles of the eye

Move the eyeball

Superior oblique attaches to the orbit anteriorly via ... then changes direction to travel laterally and attach to the ...

Trochlea Posterior sclera

When the sebaceous glands of eyelashes get blocked, they inflame and enlarge and can result in the formation of a ...

Stye (red painful lump near edge of eyelid)

Skin of eyelid transitions into a mucous membrane called the ... lining the inner surface of the eyelids

conjunctiva

The conjunctiva covers the front of the sclera but doesn't cover the...

cornea

Is the conjunctiva vascular

Yes

Why would it be bad if the conjunctiva covered the cornea

Conjunctiva is very vascular and blood vessels often leak so don’t want the conjunctiva sitting in front of transparent cornea and decreasing amount of light that passes through

Levator palpebrae superioris originates from the apex of the orbit and attaches to what 3 things

a bit of the conjunctiva, a bit of the tarsal plate and to skin of the upper eyelid

What within the eyelid gives it form/shape

Tarsal plate

What does the tarsal plate contain

Meibomian glands which secrete oil - this oil coats the tear film and stops it evaporating

What does the lacrimal apparatus consist of (3)

Lacrimal gland Lacrimal sac Nasolacrimal duct

Lacrimal gland function

secretes tears, these tears coat the front of conjunctiva and the cornea

Where do tears secreted by lacrimal gland drain into

medial side of eye (through punctae) into lacrimal sac

Tears from lacrimal sac drain into what

Nasolacrimal duct then into the nasopharynx

Location of lacrimal gland

Lateral roof of orbit

Innervation of lacrimal gland

Parasympathetic fibres of facial nerve

Location of lacrimal sac

Medial wall of orbit

Arterial supply of structures inside orbit

Ophthalmic artery

Largest branch of ophthalmic artery | + name other branches of the ophthalmic artery

Central retinal artery Short posterior ciliary arteries Long posterior ciliary arteries

Central retinal artery travels within what nerve

CN II

What is the retina's dual blood supply

Central retinal artery supplies inner layers of retina Choroid supplies outer layers of retina

What is the optic disc also known as due to no rods or cones being present

Physiological blind spot

What veins drain the orbit (2) + what sinus do they drain into

Superior and inferior ophthalmic veins Cavernous

How is the transparency of the cornea maintained (3)

1. REGULAR ARRANGEMENT OF COLLAGEN IN THE STROMA 2. NO BLOOD VESSELS 3. ENDOTHELIUM LAYER contains a pump that actively keeps AH out of the cornea

Why is the cornea said to be an immune privileged site

Due to it being avascular, there’s less chance of foreign antigens from a corneal graft being recognised by the recipient so lesser chance of graft rejection

How many layers does the tea film have + describe each layer

Layer 1 - mucinous layer overlying corneal epithelium Layer 2 - aqueous layer lies over mucinous layer (MAJORITY OF TEAR FILM) Layer 3 - oily layer is the most superficial (smallest layer

Which layer of the tear film is the most superficial layer

Layer 3 - the oily layer

Which layer of the tear film makes up the majority of the film

Layer 2 - the aqueous layer

Functions of tear film (3)

Keeps corneal moist Wash away foreign bodies Has antibodies and lysozymes to kill microbes

Intro to nervous system + anatomy of eye Flashcards

(66 cards)