ANA - W12 Flashcards
Realtions of orbit
Superior: anterior cerebral fossa; forntal sinus
medial: ethmoidal labyrinth
inferior: maxillary sinus
laterally: temporal fossa
dorsal: cavernous sinus
dorsal and inferior: infratemporal fossa; pterygopalatine fossa
contents of orbit
neurovascular structure, lacrimal gland, extra-ocular muscles
retrobulbar fat (orbital fat body
fascial sheat of eyeball(TENONS CAPSULE)
Segments of eyeball
anterior segment: part of smaller sphere, around 7-8 mm
(nodal point)
posteriro: larger, 11-12mm
equator + meridianis-skjekk bilde
pole and axis of eyebal
anterior pole: detemined by corneal vertex(medial to apex, lien of sight/visual axis run throug)
(nodal point-lens)
posterior pøe: right behind
external axis of eyeball
optic axis: axis about which the ey rotated by extra-ocular muscles
visual axis: connect seen object with the central focus point of image in the retina (fovea provid highe resolution)
Fibrous coat of the eyeball
EXTERNAL LAYER
Cornea: anterior segment
- transparent, colorless
- nin-vascular, but many nerves
- 1mm thick, thin at center
- aqueous humour is drained into sinus venossu sclerae
Sclera: posterior segment
- firm and portective membrane( over extra-ocular muslces
- white fibrous connective tissue-avascular, supplies by episcleral vessles
- sclerocorneal junction: sulcus sclerae-corneal limbus
- posteriorly pierced by optic nerve and by minute orifices that transmit ciliary nerves and vessels
where does the scleral venous sinus(canal of schlemm) run
runs circulary in the substance of sclera at the lvl of iridocorneal angle
Vascular coat of eyeball
ant seg-c
- intermediate layer
Ciliary and iris: ant seg
CILIARY BODY
- ant border of chorid
- complete rign around eyeball
- posterior surface covered by pigmented layer of retina=ciliary part of the retina
- ciliary process: radiating folds, serve to attachemtn of zonular fibres=ligaments of the suspensory apparatus of lens(preequatorial, equatorial and post equatorial)
- ciliary muscle: smoot muscle fibre, conctract–>decrease size of ring, PS oculomotor n
- fucntion: produced aqueous humour, responsible for suspension of lens and for accommodation for vision of the near object
-cont: lens more round
vascula coat: ant seg-i
IRIS
- thin, circular, contractile
- pupil:opening where ligth is admitted to post par of eye
- divide space bwteen cornea and lens into ant and post chambers
- iridocorneal angle–>scleral venous sinous
- pupillary and ciliary margins
-outer border: major circulus arteriosus of irus
- inner: minor
- posterior surface: pigmented epithelium-iridial part of retina
COMPOSED OF:
- connective tissue, vessles and n
- pigmented epi
- muscular fibres-ivoluntary
- sphincter pupillae muscle: circular fibres,- contraction decrease pupillary opening=myosis
dilatator pupillae m: radiating, cont increase opening=mydriasis
What does color of iris depend on: thhickness of stroma of iris, density and filling of vessles, pigment on post surface of iris
function: regulation of amount of light entering into the eye
Sensory part of the eyeball- the retina
- internal layer
Nonvisual part of retina: ant formed by ciliary and iridial parts of retina
- cover internal surface of ciliary bodu and irid
- no cons or rods.
JUNCTION IS IRREGULAR LINE: ORA SERRATA
Optic part of retina: post formed by nervous tissue of retina
- delicate, soft, translucent neural membran-adapted for reception of light stimulus
- contain rods and cons
- outer surface contact with choroid
- optic disc where nerve leave, no light sensitive receptor cells=macula caeca=blind spot of retina
- in center of disc=depression perced by central a and vein of retina
- macula lutea-yellow spot: laterally from optic disc-central depression=fovea centralis where visual sense is the most perfect(only cones)
- no vessles
difference between rods and cones
rod:
- sensitive to light
- vision in dim light
- 120 mil per eye
cones:
- best in bright lgiht
- high-acuity color vision
-6-7 mill per eye
contencts of eyeball-lens
transparent, colorless, biconvec body, firm and lack vessles
ant and post surfaces meet in equator
behind iris, attached to ciliary body by fibres forming suspenosry ligmanet of lens=zonular fibres
enclosed in capsule of lens
function: changes focus from distant to near object by action of ciliary muscles–>chnage shape of lens =accommodation->adaption fo eye for seeing objects at various distances
hyperopia: farsightedness
myopia: near
other contents of eyeball besides lens
Viterous body:
occupied vitreous changer, is clourless, structureless, transparetn, gelatinous consistency because of hyaluronic acid
Vitreous membrane
ant shows deep concavity-hyaloid fossa-contain lens
ant chamber: between cornea and iris
post chamber: between iris and vitreus body (contain ciliary body, lens and zonular fibres)
aqueous humor: produced by ciliar body to posterior chamber: post chamber–>pupill–>ant chmaber–>scleral venous sinus
accessory organs of eye
orbital muscles
superior rectus, inferior rectus, medial rectus, lateral
rectus, superior oblique, inferior oblique mm.,
levator palpebrae superioris
O: common tendinous ring (except inf. oblique m.)
I: eyeball - sclera (except levator palpebrae sup.)
NS: III., IV., VI
orbital fasciae
eyelids-palpebrae
conjunctiva
palpebral conjunctiva and scleral conjunctiva
lacrimal apparatus-gland, canaliculi, sac, nasolacrimal duct
