2. Anatomy of the eye
Orbit : Cavity/bony socket containing the eyeball
3. External Structures : -Lacrimal gland (secretes tears)
-Lacrimal Canaliculi (collect
and drain the tears
-Lacrimal sac (empties the tears
into the nasolacrimal duct)
-Nasolacrimal duct (empties the
tears into the nasal cavity)
4. External structures : -Palpebrae (eyelids)
-Palpebrae fissure
-Canthus (corner of the eye where
the superior and inferior palpebrae meet)
-Conjunctiva (colorless and thin
mucuous membrane lining the underside of the eyelids
and covering the sclera)
7. Outer Layer : -Cornea/Window of the eye (transparent)
Controls and focuses the entry of light
into the eye
-Sclera (white)
8.
9. Middle Layer : - Iris (contains the eye color. Forms the
Pupil)
-Ciliary body (holds and moves the
lens. Secretes aqueous humor that provides nutrients
to the cornea lens and other tissues)
-Choroid (lines the sclera)
10. Innermost layer : -Lens (colorless, accomodation)
-Retina (rods and cones)
-Fovea Centralis Retinae (cones
located in the middle of the macula lutae/yellow spot)
-Optic Nerve (enters at optic disk)
13. Physiology of the Eye
Light passes through the cornea, aqueous humor, lens,
then vitreous humor to reach the photoreceptors
(cones and rods). Theses photoreceptors contain
chemicals (some of them derived from Vit A) that
cause electrical impulses transmitted to the optic
nerve, which sends signals to the brain. The brain will
interpret and create visual images.
14.
15. Common Refractive Disorders
Astigmatism : Blurry near or distant vision due to the
imperfection in curvature in the cornea or lens
16. Myopia : Nearsightedness
Presbyopia : Nearsightedness in old age
31. Amblyopia : Blurred image sent to the brain by a lazy
eye whose nerve pathway did not develop during
childhood. This confuses the brain, and the brain may
learn to ignore the image from the weaker eye
41. Inner ear/Labyrinth : -Cochlea (bony spiral structure
containing the cochlear ducts filled with fluid/
endolymph. Contains the organ of corti that has nerve
endings transmitting sound vibrations to the 8th nerve)
-Vestibule (central part of the
labyrinth)
-Semicircular canal (filled with
endolymph/fluid and cilia that detect head motion to
maintain balance)
-Eustachian tube (links the
middle ear to the nasopharynx)
42.
43. Physiology of the Ear
Sound waves enters the ear→ vibrations of the
eardrum→ bones in the middle ear move back and
forth→ movement of the fluid in the cochlea. The
hair cells in the cochlea will sense the motion
(movement) via their cilia and convert that motion to
electrical signals/impulses that will be sent to the
auditory nerve. The brain interprets the message and
create sounds.
44.
45. Hearing Loss
Conductive : Damage to the auditory canal
Sensorineural : Damage to the cochlea or to the nerve
pathways
52. Common disorders associated with the
Inner Ear
Tinnitus : Ringing or roaring in the ear
Meniere’s disease : Idiopathic, affects hearing and
balance
Presbycusis : Mostly in older adults
53. The Senses of Taste and Smell
Olfactory Cells : In the roof of the nasal cavity
Taste Buds : Sweet→Salty→Sour→Bitter