Anatomy and physiology of eye by maghan das

1. Dow University of HealtH sciences
institUte of nUrsing
Human eye
Maghan Das
BscN Student
10th
September, 2014
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2. Eye
Accessory structures
Eye lids
Upper eye lid
Lower eye lid
It is also known as Palpebrae
Upper is more movable
Upper eye is of Composed of levator palpebrae
superioris muscle
Protect the eye from excessive light and foreign
bodies
Space between upper and lower eye lid is called
palpebral fissure
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3. Conti…
•Meibomian glands are sebaceous glands that secrete
an oily lubricating material into the lids.
•In the inner canthus, the caruncle is the small fleshly
mass containing sebaceous glands
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5. Conjunctiva
• It is transparent
• Composed of stratified columnar epithelium
• Palpebral Conjunctiva lies at inner of eye lids
• Bulbar Conjunctiva lies at eye ball
• It covers the sclera, not cornea
Eye lashes
• Which protect the from border of eye lids
Eye brows
• Protect the eye ball from foreign objects
• Sebaceous ciliary glands lies at the base of hair follicles of
eye lashes and release the lubricating fluid in follicles
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6. Lacrimal apparatus
•Almond shape
•lacrimal glands secrete tears which drain into the
puncta, then the nasolacrimal sac, then the duct
which empties into the inferior meatus of the nose
•Parasympathetic fibers of facial nerve VII
•Lacrimal fluid contains salts, mucous and lysozyme
•Each gland produces 1 ml lacrimal fluid per day
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7. Eye muscles
Six extrinsic eye muscles
• Superior rectus
• Inferior rectus
• Lateral rectus
• Medial rectus
• Superior oblique
• Inferior oblique
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11. Eye ball
•It measures about 2.5 cm in diameter
•One-sixth is exposed
•It is composed of three layers
• Fibrous layer
• Vascular layer
• Nervous layer
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12. Fibrous layer (outer layer)
• Cornea
•Transparent layer
•Covers iris
•Refract the light
•It has three coats
• Outer surface consist of non keratinized stratified epithelium
• Middle coat consist of collagen fibers and fibroblast
• Inner coat is consist of sqamous epithelium
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13. Sclera
•It is called white of eye
•Composed of dense connective tissues
•It covers the eye ball except cornea
•Serves as an attachment for the extraocular
muscles
•Helps maintain the shape of the eyeball
•It is rigid and protect the inner structures
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14. Vascular layer
• Choroid
•Absorb excessive light
•Contain network of blood vessels to supply
oxygen and nutrients
•Nemours blood vessels
•It contains melanocytes
•Melanin in choroid absorbs stray light rays
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15. Ciliary Body
•Ciliary processes produce aqueous humor
•Attach with zonular fibers with lens
•The muscles of the cilliary body control the
thickness of the lens.
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16. Iris
 Colored portion of eye ball
 It is suspended between cornea and lens
 It contains melanocytes and smooth muscle fibers
◦ Brown and black eyes --- large amount of melanin
◦ Blue eyes ----very low melanin
◦ Green eyes ------ moderate melanin
 The muscles in the iris control pupillary constriction.
 Stimulation of the parasympathetic branch of CN III causes
constriction
◦ Contraction ---- circular muscle
◦ Dilation ----Radial muscles
 Stimulation of the sympathetic branch causes
dilation
 Divides the anterior chamber and posterior chamber
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17. Nervous layer (Retina)
• Inner layer
• It has two layers
• Pigmented layer
• Neural layer
• Pigmented layer contains melanin which absorbs stray light
• Neural layer is consist of three layers
• Bi polar layer ---- horizontal cells and amacrine cells
• Ganglian cell layer
• Photoreceptor layer
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18. Photoreceptor
•Two types of Photoreceptor
Cones
•Bright light stimulates cones
•Each retina has 6 millions cones
Rods
•Each retina has 120 millions rods
•Dim light stimulates rods
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20. Macula
• Highest concentration of cones
• Fovea centralis
• Center of macula
• Contains only cones and no rods
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21. Optic disc (Blind spot)
•It does not contain rods and cones
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22. •Lens
• A transparent crystalline biconvex structure immediately behind the iris
• Suspended from ciliary body by threadlike ligaments called zonules
• Refracts light
• Focuses light on the retina
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23. •Anterior Compartment
• Aqueous Humor
•Fluid that nourishes the lens and epithelial cells
•Help refract light onto the retina
•Posterior Compartment
• Vitreous Humor
•Clear gel
•Helps refract light onto the retina
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24. • Optic Nerve
• Transmits electrical impulses from
the retina to the brain
• The blind spot is located at the
optic nerve head or optic disc
where there are no photoreceptors
• Retinal Blood Vessels
• Arteries transmit oxygen and
nutrients
• Veins carry deoxgenated blood
from the eye
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