L16: The Eye Flashcards
list the tunics of the eye
- fibrous tunic
- vascular tunic
- inner tunic
fibrous tunic: basic
- -sclera (tunica fibrosa)
- -cornea
vascular tunic: basic
- -choroid
- -ciliary body
- -iris
inner tunic: basic
retina
fibrous tunic: sclera layers
- episcleral layer
- sclera proper
- lamina cribrosa
episcleral layer
- outer layer
- loosely arranged collagen and elastic fibers
- highly vascular
- attaches the lining of the eyelid to the sclera
sclera proper
- made of interlacing collagen fibers
- attachment site for tendons of extrinsic eye muscles
- collagen bundles are parallel to outer surface of sclera
lamina cribrosa
- perforated disc of sclera
2. pass thru for optic nerve fibers
anteriorly the sclera is continuous w/
the cornea
limbus
the junction between cornea and sclera
highly vascularized
posteriorly the sclera is continuous w/
the dural covering of the optic nerve
fibrous tunic: cornea layers
- corneal epithelium
- bowman’s memb.
- corneal stroma
- Descemet’s memb.
- corneal endothelium
corneal epithelium
- stratified, nonkeratinized squamous 5-6 layers
- highly mitotic in basal layer
- turnover 1 wk
bowman’s membrane
- cornea layer 2
- acellular layer separates epithelium from stroma
- random collagen fibers
corneal stroma
thin layers of ordered collagen fibers
Descemet’s membrane
- cornea layer 4
- acellular layer of collagen bundles
- separates stroma from endothelium
corneal endothelium
single layer of large squamous cells
in contact w/ aqueous humor of the eye
choroid
- extends ant. to ora serrate of retina
- highly vascularized w/ loose CT
- bruch’s (glassy) memb.
**vascular tunic
vascularization of choroid
- forms choriocapillary network
- provides nutrients to outer retina
- contains melanocytes
choriocapillary network
contains small blood vessels that supply cells of the retina
part of choroid
Bruch’s membrane
part of choroid
acellular fused basal laminae of choriocapillaris and pigmented retinal epithelium
ciliary body
- vascular tunic
- wedge shaped expansion of choroid
- peripheral to lens
- double layer of cells
- suspensory ligaments
- ciliary muscles
main function of ciliary body
to produce aqueous humor
ciliary body: cell layers
- innermost layer is continuous w/ pigmented layer of retina
- surface layer from sensory layer of retina
- produces aqueous humor
ciliary body: suspensory ligaments
extend to just behind lens equator
anchor the lens in place
ciliary muscles
–smooth muscle mass that changes the shape of the lens
–innervated by parasympathetic neurons
ciliary muscles and accommodation
–one group of muscles for flattening the lens
–another for allowing lens to become thicker
______ surface layer of cells produces _______ : ciliary body
nonpigmented
aqueous humor
secrete into posterior chamber
aqueous humor
- percolates thru trabecular meshwork
2. flows into canal of schlemm
Vascular tunic is made up of the ?
Iris
Iris components
Angles
Double layer of epithelium
Melanocytes
The iris is located _______ to the lens and separates ?
Anterior to lens
Separates anterior and posterior chambers
Iris angle
Formed at lateral borders of the anterior chamber
Made of loose CT
Passageway for aqueous humor
The iris surrounds to ?
Pupil
Iris: double layer of epithelium
- Inner layer - pigmented epithelial cells
- Outer layer - radially oriented myofilaments
- Concentric layer - myofilaments
Iris outer layer of epithelium
- dilator pupillae muscle
- sympathetic innervation will dilate pupils
Iris concentric layer
- constricts the pupil
- parasympathetic innervation
________ innervation will dilate the pupil, whilst _______ constricts.
Sympathetic dilates
Parasympathetic constricts
Iris melanocytes
Pigment producing cells
The more melanocytes you have, the darker the iris
______ color pigments do not exist in nature.
Blue
Inner tunic is made up of the ?
Retina
Subdivisions of the retina, divided by the ______ ?
Divided by ora serrata
- Photosensitive region - post. To ora
- Nonphotosensitive region - ant. To ora
Photosensitive region of retina
- Optic disc
2. Fovea centralis
Optic disc
Region of posterior eye where optic nerve is
Has no photosensitive retina and makes up the blind spot
Fovea centralis
Just lateral to optic disc
Yellow pigment
Only cone photoreceptors
Area of most acute vision and color vision
______ makes up the blind spot
Optic disc
_______ is the region of highest visual acuity
Fovea centralis
Non-photosensitive region of the retina
Consists of two cell layers covering the iris, ciliary body and ciliary processes