anatomy of the eye and orbit Flashcards
What is the function of the cornea
The anterior 1/6 of the fibrous coat of the eye - Transparent and is a window to allow light rays to enter the eye balls - the collagen fibres are all the sam diameter and distance apart which allows light to enter without becoming scattered
What is the function of the sclera
The opaque posterior 5/6 of the fibrous coat which gives attachment to the muscles of the eye
What is the function of the cilliary body
Suspends the lens and produces aqueous humor
What is the function of the iris
The colourful part of the eye - controls the diameter of the pupil and therefore how much light enters the eye
What is the function of the retina
Has light sensitive rods and cones which lets us see
What is the function of the choroid
Supplies blood to outer layers of the retina
What is the lens
Transparent crystalline biconvex structure which is suspended by zonules which are suspensory ligaments which come from the cilliary body
What is the anterior segment of the eye and what does it contain
Infront of the lens - aqueous humor
What is the posterior segment of the eye and what does it contain
Posterior to the lens - contains vitreous humor
What is the function of the aqueous humor
Maintains the intraocular pressure
What is the function of the vitreous humor
helps cusion the retina
Which nerve innervates to help close the eyelids
Facial nerve (CN VII)
Which nerve helps elevate the eyelids
(CN III) - occulomotor nerve - controls LPS
What is the conjuctiva
Thin vascular membrane that covers the inner surface of the eye lids but not the sclera
Describe the lacrimal apparatus and crying
The lacrimal gland is situated in the orbit laterally. Parasympathetic from Facial nerve. Its ducts open into the conjunctival sac
During each blink, eyelids spread tears evenly on the surface of cornea
Tears drain through punctae on the medial side of each eyelid
Drains into lacrimal sac which sits over the lacrimal bone
Then drains through nasolacrimal duct into the inferior meatus of the nasal cavity.
What muscles constrict the pupil and what innervates it
Constrictor pupillae - innervated by CN III - occulomotor
What muscle dilates the pupil
Dilator pupillae
What is the innervation of the extrinsic ocular muscles
SO4 LR6 everything else is 3
Superior oblique - trochlear nerve CN IV
Lateral rectus - CN VI - abducens nerve
What innervates the lacrimal gland
Opthalmic division of trigeminal nerve (CNV1)
Describe the central retinal artery and what it supplies
Travels within the substance of the optic nerve and supplies inner layers of the retina
What supplies the other parts of the retina which the central retinal artery doesn’t supply
Posterior cilliary artery
