This PowerPoint presentations covers the anatomy and physiology of the eyes, ears, nose and mouth; and common disorders.

1. The Special
Senses
Prepared by Mickelder Kercy, MD - Instructor

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)

6.  Extrinsic muscles : -Levator palpebrae superior
-Superior rectus
-Inferior rectus
-Lateral rectus
-Medial rectus
-Superior oblique
-Inferior oblique

7.  Outer Layer : -Cornea/Window of the eye (transparent)
Controls and focuses the entry of light
into the eye
-Sclera (white)

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)

12.  Anterior cavity : -Anterior chamber (aqueous humor)
-Posterior chamber (aqueous humor)
Posterior cavity : -Vitreous humor/body

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.

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

17.  Hyperopia : Farsightedness

18.  Strabismus : Crossed eyes/wall eyes

19. Disorders related to structural
irregularities
 Blepharoptosis : Drooping of one/both eyelids

20.  Ectropion : Lower eyelid turns outward/everts

21.  Entropion : Eyelid folds inward/inverts

22.  Exophthalmos : Bulging of one/both eyeballs

23. Infectious Eye Disorders
 Blepharitis : Inflammation of the eyelids

24.  Conjunctivitis : Inflammation of the conjunctiva

25.  Hordeolum : sty or pus-filled swelling at the base of
an eyelash

26. Age-Related Eye Disorders
 Cataracts : Clouding/Opacity of the lens

27.  Retinal Detachment : Retina detached from the
choroid

29.  Macular Degeneration : Degeneration of the macula

30.  Nyctalopia : Nightblindness

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

32.  Corneal Abrasion : Lesion/abrasion on the cornea

33.  Diplopia : Double vision

34.  Glaucoma : Increased pressure in the eye causing the
visual field to decrease

35.  Nystagmus : Nystaxis/involuntary repetitive eye
movement

36.  Retinopathy : Diseases of the retina that affect the
blood vessesls. Found in diabetes and Hypertension.

37.  Photophobia : Sensitivity to light

38. Slit Lamps

39. Anatomy of the Ear
 External Ear : -Pinna/auricle
-Auditory canal/auditory meatus
(secretes cerumen/earwax)
-Tympanic membrane/eardrum
-Fundus/floor of the tympanic membrane

40.  Middle Ear : -Malleus/hammer
-Incus/anvil
-Stapes/stirrups

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)

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.

45. Hearing Loss
 Conductive : Damage to the auditory canal
 Sensorineural : Damage to the cochlea or to the nerve
pathways

46. Audiometer and Tuning Fork

48. Common disorders associated with the
outer ear
 Impacted Cerumen : Earwax that has hardened
obstructing the ear canal

49.  Ruptured tympanic membrane : Tear in the tympanic
membrane

50. Common Disorders associated with the
Middle Ear
 Otitis Media : Inflammation of the middle ear

51.  Otosclerosis : Overgrowth of spongy bone around the
stapes

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

54. The End