Eye Flashcards
Three tunics (layers) of the eye
Fibrous tunic
Vascular tunic
Neural tunic
Fibrous tunic
Outermost layer; tough outer coat. Includes:
-Sclera
-Cornea
Vascular tunic
Middle layer; pigmented and vascular. Includes:
-Choroid
-Ciliary body
-Iris
Neural (nervous) tunic
Inner layer. Includes
-Retina with photosensitive and nonphotosensitive portions
Stroma
Narrow and regularly arranged type 1 Collagen fibers in the cornea that allow it to be transparent
Low water content and avascularity helps make it transparent
Tapetum lucidum
Reflective region in posterior dorsal part of choroid; responsible for “nightshine”
Present in all domestic animals but pigs. Not present in humans
Not pigmented
Layers of the cornea
-Corneal epithelium
-Anterior limiting membrane
-Corneal stroma
-Posterior limiting membrane
-Posterior corneal epithelium
Ciliary body
Wedge shaped structure located between iris and choroid
Contains ciliary muscle - adjusts shape of lens for near/far vision
Iris
Located between anterior and posterior chambers of eye
Pupil opening in center
Dilator pupillae m. - sympathetic innervation
Sphincter pupillae m. - parasympathetic innervation
Lens
Biconvex disk located directly behind iris
Focuses light rays on retina
Held in place by zonule fibers from ciliary processes
Limbus
Junction of cornea and sclera
Choroid
Vascularized, pigmented, posterior portion of vascular tunic
Composed of network of collagen and elastic fibers
Photosensitive part of retina
Pars optica
Includes photoreceptors (rods and cones)
Signal pathway and light pathway run in opposite directions
Sclera
White, opaque layer of Type 1 collagen fibers
80-85% surface of the eye
Few blood vessels
Optic disc
Exit spot for optical ganglion. Exit into optic nerve
No neural retina at this spot - “blind spot”
