chapter 6

SENSORY SYSTEM – OPHTHALMOLOGY AND OTOLARYNGOLOGY

Chapter Overview

  • Focuses on the anatomy, function, and pathology of the eye and ear systems.

EYE

Major Function

  • Function of the Eye: Provides sight.

  • Root Words Related to the Eye:

    • Ocul/o

    • Ophthalm/o

    • Opt/o

Anatomical Components

  • Blephar/o:

    • Eyebrow

    • Upper Eyelid

    • Eyelashes

    • Lower Eyelid

  • Lacrimal Apparatus:

    • Lacrimal Gland: Produces tears.

    • Lacrimal Ducts & Sac: Tears flow from the lacrimal gland, over the eye, through the duct to the sac, then drain into the nasolacrimal tube, causing a runny nose.

    • Root Words: Lacrim/o, Dacry/o

Conjunctiva

  • Definition: An "invisible" membrane lining both the eyes and eyelids.

  • Function: Produces serous fluid for eyelid movement.

  • Root Word: Conjunctiv/o

External and Internal Eye Structures

  • Cornea:

    • Definition: Transparent front part of the eye.

    • Root Words: Corne/o, Kerat/o (also means keratin - horny skin)

  • Sclera:

    • Definition: The white outer coat of the eyeball.

    • Root Word: Scler/o (also means abnormal hardening)

  • Choroid Layer:

    • Components:

    • Iris: Colored area, controls pupil size.

    • Lens: Bends light rays.

    • Ciliary Muscles: Attach to lens and assist in focusing.

  • Retina:

    • Definition: Innermost layer of the eye, contains photoreceptor cells that convert light into electric signals sent to the brain via the optic nerve.

    • Root Word: Retin/o

Additional Structures

  • Humors:

    • Aqueous Humor: Anterior humor in front of the lens.

    • Vitreous Humor: Posterior humor behind the lens.

  • Root Words: Vitre/o, Aqueous

Eye Conditions and Disorders

  • Vision Abnormalities:

    • Emmetropia: Normal vision.

    • Myopia: Near-sightedness.

    • Hyperopia: Far-sightedness.

    • Astigmatism: Irregular vision.

Types of Vision

  • Photopic Vision:

    • Occurs during bright light; increased color perception; requires central vision and both rod and cone photoreceptors.

  • Mesopic Vision:

    • Occurs during twilight; mixed color perception; uses rod and cone photoreceptors.

  • Scotopic Vision:

    • Occurs in dim light; poor visual acuity; relies heavily on rod photoreceptors.

Common Eye Terms

  • Amblyopia: Poor visual acuity also known as "lazy eye"; combination of "Ambly (dull) + -opia (vision condition)".

  • Miosis: Abnormal pupil contraction.

  • Mydriasis: Abnormal pupil dilation.

  • Blepharoplegia: Paralysis of the eyelid.

  • Xerophthalmia: Dry eyes.

  • Scotoma: Dark spot in the visual field.

EAR

Structures of the Ear

  • Parts of the Ear:

    • Outer Ear: Auricle (Pinna), External Auditory Canal, Mastoid Process.

    • Middle Ear: Eardrum (Tympanic Membrane), Auditory Ossicles (Malleus, Incus, Stapes).

    • Inner Ear: Cochlea, Vestibular System, Eustachian Tube.

  • Root Words: Aur/o, Ot/o, Acous/o, Audi/o

Common Ear Conditions

  • Cerumen: Earwax (Cerumin/o).

  • Mastoidalgia: Pain in the mastoid region (Mastoid/o + -algia).

  • Tinnitus: Ringing in the ears; originates from the Latin term "to ring".

  • Vertigo: Sensation of motion while stationary.

Types of Hearing Loss

  • Sensorineural Hearing Loss:

    • Caused by damage to the inner ear or auditory nerve.

  • Conductive Hearing Loss:

    • Due to problems in the outer or middle ear preventing sound from being conducted correctly.

Examination Tools

  • Devices to Examine the Eye:

    • Tonometer: Measures intraocular pressure.

    • Ophthalmoscope: Instrument for examining the interior of the eye.

    • Retinoscope: Used for retinoscopy.

  • Devices to Examine the Ear:

    • Otoscope: Instrument for looking at the ear.

    • Audiometer: Measures hearing ability.

Special Procedures

  • Enucleation: Removal of the eye, leaving muscles and orbital contents intact; indicated by ocular tumors, severe trauma, or pain.

  • Blepharoplasty and Keratoplasty: Surgical procedures to correct eyelid and corneal problems.

Common Ear Disorders Terminology

  • Otitis Externa: Inflammation of the outer ear.

  • Otitis Media: Inflammation of the middle ear.

  • Myringotomy: Incision into the eardrum to relieve pressure.

Medical Professionals in Eye and Ear Health

  • Ophthalmologist: A medical doctor specializing in eye and vision care.

  • Optometrist: A specialist in measuring vision and prescribing glasses.

  • Audiologist: Specialist in hearing disorders.

  • Otolaryngologist: Specialist in disorders of the ear, nose, and throat.

  • Otoneurologist and Otorhinolaryngologist: Specialists combining ear and neurological disorders.

Acronyms Related to Eye and Ear Health

  • Eye: HEENT, OD, OS, OU, PERRLA.

  • Ear: EENT, ENT, TM, AOM, OM.

Pharmacology in Ear Treatment

  • Ceruminolytic: A drug that aids in breaking down earwax.

  • Cochlear Implant: Device that stimulates cochlea to increase sound.