1.Fibroustunic（1)Cornea（anterior1/6）Transparent,non-vascularSensitiveto stimulation·HighlycurvedScleraOpticN
• Transparent, non-vascular • Sensitive to stimulation • Highly curved 1. Fibrous tunic （1）Cornea （anterior 1/6） Optic N. Sclera
(2)Sclera（posterior5/6）.White,dense,opaque·Maintainingtheformoftheeyeball.Sinus venosus sclerae a circularcananl drainingthe aqueous humour·ispiercedbytheopticnervefibers and continuouswithduramaterPOTaCanat ot SohinnAteriorchembeDitatorta)Sphinctior (M)SoaX华Lengry epithelum (B)Caliarymuscle (M)Optic N
• White, dense, opaque • Maintaining the form of the eyeball • Sinus venosus sclerae ①: a circular cananl draining the aqueous humour • is pierced by the optic nerve fibers and continuous with dura mater （2）Sclera （posterior 5/6） Optic N. ①
2.Vasculartunic·Brown,richinbloodvessels&pigmentcells·Provide the nutritionfor thetissues insidethe eyeballAnterior→posterior:iris,ciliarybody,choroid①Iris②Ciliarybody③Choroid
2. Vascular tunic • Brown, rich in blood vessels & pigment cells. • Provide the nutrition for the tissues inside the eyeball. • Anterior → posterior：iris, ciliary body, choroid ① Iris ② Ciliary body ③ Choroid
(1)Iris.The anterior coloured part ofthe vasculartunic·isacircularperforateddiaphragmwithcoronaryposition·near its centeris around aperturenamed pupi·The colourofiris variesfromdifferentracesIrisLens
• The anterior coloured part of the vascular tunic • is a circular perforated diaphragm with coronary position • near its center is a round aperture named pupil •The colour of iris varies from different races （1） Iris Iris Lens
.Pupillary sphincterM.decreasesthepupil:bright light,look at nearobject.Pupillary dilatorM.enlarges thepupil:dim light,look at distant objectPupilPupil constrictsasPupil dilates ascircularmusclesofirisradialmusclesofiriscontract(parasympathetic)contract(sympathetic)Bright lightDim lightNormal light
• Pupillary sphincter M. decreases the pupil: bright light, look at near object • Pupillary dilator M. enlarges the pupil: dim light, look at distant object