The orbit Flashcards
Bones of orbit surrounding outside-
Frontal, zygomatic, maxilla
Bones in wall of orbit
Ethmoid, lacrimal, superior orbital fissure, sphenoid - greater wing and lesser wing, optic canal
Orbit contents
Eyeball, Fat and connective tissue, Extraocular muscles, nerves and blood vessels
Tarsal Plates
Dense C/T
Support eyelid
Glands
Ligaments of eye
Medial check ligaments
Lateral check ligaments
Suspensory ligaments
Suspensory ligaments
Support eyeball
Check ligaments
Restrict medial and lateral recti
Cornea
Fibrous layer outercoat
Sclera
Fibrous layer outercoat
Retina
Inner layer / coat
Rods and cones
Vascular layer - middle coat
Iris
Ciliary body
Choroid
Retina
rods and cones
blind spot =optic disc
Macula Lutea = Fovea
Aqueous humour
Anterior to lens, helps maintain intra-ocular pressure
Made by ciliary body, drain into corneo- scleral junction
(canal of schlemm)
Vitreous humour
Embryological jelly
Transparent jelly
Posterior to lens
supports the retina
intraocular (intrinsic) muscles
Dilator pupillae
Sphincter pupillae
Dilator pupillae
increases diameter of pupil
sympathetic, carried on blood vessels
Sphincter pupillae
decreases the diameter of
parasympathetic via oculomotor nerve CN III
ciliary muscle in the absence of nerve stimulation
ciliary muscle relaxed
zonular fibres are under tension
lens is stretched thin to refract light for distant vision
Ciliary muscle under parasympathetic stimulation
ciliary muscle contract
zonular fibres relax
In the absence of stretching internal tension causes lens to become more spherical (thicker) to refract light for near vision
7 extraocular muscles
levator palpebrae superioris from orbital roof to upper eyelid
Superior, inferior, medial and lateral recti from annular ring to sclera (anterior to sclera)
Superior oblique (lesser wing sphenoid) and inferior oblique (orbital floor) to sclera (posterior equator)
