Applied Anatomy and Physiology of the Orbit and Eye Flashcards
What is the three layers of the eye ball
Fibrous
Vascular
Sensory
What is the fibrous layer composed of
Cornea 1/6 = anterior
Sclera 5/6 = posterior
What is the layer of the cornea that faces the air
Stratified squamous non keratinised epithelium
What is the name of the basement membrane for the top layer seen of the corneal
Bowmans membrane
What is the layer of the cornea that faces the aqueous humour
Simple squamous endothelium
What is the name of the basement layer of the second surface of the corneal
Descemets layer
What is found between the two surfaces of the corneal
Stroma - regular arranged collagen
What is not present in the stroma of the corneal
Blood vessels
What three features of the corneal allow it to keep its transparency
The regularly arranged collagen
No blood vessels
- could leak and would rearrange collagen
endothelium cell layer having pump
How does the regular arranged collagen help with the corneas transparency
The uniformity allows light to pass through
What layer of the cornea if damaged/ pierced would scar tissue form
Below Bowmans membrane would affect your vision as scar tissue forms
How many cells are normally person tin the endothelium of the cornea and why is this important
2500cells/mm2
Important as cant have cell loss as may cause aqueous humour to move into stroma
Where does the cornea receive its nutrition due to the absence of blood vessels
via diffusion
The tear fluid at the outside
The aqueous humour at the inside
The blood vessels in the sclera all around
What is the constant pressure in the cornea
There is a constant intraocular pressure pushing aq humour into stroma
What is the benefit of the endothelial pump
Pushes aq humour out of cornea stroma as needs to be removed to retain transparency
What is the clinical benefit of corneal avascularity
In the procedure of corneal graft there is a lesser chance of rejection
giving its an immune privilege
What is the function of the sclera
gives attachment to muscles moving eye balls
What is the vascular layer of the eyeball composed of
Choroid
Ciliary body
Iris
What is the function of the choroid (orange part)
supplies blood to outer layer of retina
What is the positioning of the iris
Hangs infront of lens, and is incomplete anteriorly due to pupil
What is the function of the iris
Controls the diameter of the pupil
dictating how much light is allowed in
What muscles control the iris functions
Pupil dilator -
Radial muscle
Pupil constrictor - Spinchter muscle
What is the two functions of the Cilliary body
Contains muscles that help change the shape of the lens
Produces aqueous humour
What is the pathway of aqueous production to drainage
Aqueous humour is produced by cilia body in the posterior chamber
Flows out into anterior segment
Until angle of anterior chamber (=junction of cornea and scelra)
It then drains out through trabecular mesh work
Aqueous humor then drains out into schlemms canal which drains into veins above the sclera
What is contained in the sensory layer of the eye ball
Retina
What is blood supply to the retina
Dual blood supply
Inner layer - central retina artery
Outer layer - diffusion of fenestrated blood vessels from choroid
What is the histology and function of the fovea centraliss
Histologically packed with cones, with all outer layers pushed away to expose cones
Has maximum visual activity so where is you focus your image
What forms an image in the retina
Light sensitive rods
What is the anatomical positioning of the lens
Sits behind the pupil
suspended from ciliary body by sensory ligaments in a 360 degree fashion
What is the structure of the lens
Crystaline biconvex structure
Transparent with regular collagen and protein filaments
What is the blood vessel innervation to the lens
No blood vessels near
Whats present on the outside of the lens and what does this produce
Basement membrane forms new fibres
How does old age cataract occur
New fibres compact old fibre s of the lens, lens cant shed old fibres therefore over time the eye becomes quite opaque
Where is the posterior segment of the eye located and what is contained inside
Behind the lens
Filled with virtuous humour to cushion retina
What is contained in the anterior segment and what is its further division
Aqueous humour
Divided into
anterior chamber - infront of iris
Posterior chamber
-behind iris
What all the components contained in the anatomy of the eye socket
Bony orbit Fat adipose eye ball eyelids lacrimal duct muscles
What is the eye lid composed of
Thin skin with hair follicles and sebaceous gland
What shapes the eye lid
The hard plate/tarsal plate
What is present in the tarsal plate
Meibomian glands
What is the two muscles of the eye lid and there functions
Levator palpebrae superioiris - elevates eye lid
Obicularis oculi - closes eye lid
What is the conjuctivia
Membrane that lines the inside of the eye lid and the sclera infront - doesn’t extend over cornea
What bones compose the bony orbit
Frontal (oribital rim) ethmoid Lacrimal Nasal Sphenoid Zygomatic Palatine Maxila
What is the 3 formans of the bony orbit where neuromuscular structure arise through from the apex
Optic foramen
Superior orbital fissure
Inferior orbital fissure
What fills the remainder or pace in the orbit after the eyeball
adipose tissue - there fore support
What is the clinical important of adipose tissue in the eye orbit
Is the last reserve of fat lose
Sunken eyes = extreme weight loss
Increase in fat content in the eye in thyroid eye disease
