Special Senses: The Eyes and Ears MT Ch. 11

Adonis K. Lomibao11/23/11

Objectives

Identify the basic function and structures of the Eyes.

Identify the basic function and structures of the Ears.

The Eyes

Function- receive images and transmit them to the brain.

Structures include the eyeball and adnexa

The Eyes

The Adnexa of the Eyes

The structures outside of the eyeball They include the: Orbit (eye socket), eye

muscles, eyelids, eyelashes, conjunctiva, and lacrimal apparatus.

Adnexa-means appendages or accessory structures of an organ.

Lacrimal Apparatus:produce, store, and remove tears

The Eyeball

Aka globe, 1-inch sphere with only 1/6 of surface visible.

Sclera: (whites of the eye) maintains shape and protects inner tissue.

Choroid:middle layer, vascular: provides blood supply for eye.

Retina:converts light images into electrical impulses and transmits them to the brain.

The Uveal Tract

The pigmented layer of the eye. Consists of the:

-Choroid:provides blood supply for the eye.

-Ciliary body:in the choroid-muscles and ligaments that adjust the thickness of the lens to refine focus of light rays on the retina.

-Iris:controls the amount of light entering the eye.

Cornea, Pupil, Lens

Cornea: transparent outer surface—focuses light rays entering the eye.

Pupil: the black circular opening in the center of the iris that permits light to enter the eye.

Lens: clear, flexible, curved structure that focuses images on the retina.

Common Conditions

Conjunctivitis (pink eye)-inflammation of the conjunctiva

Corneal abrasion-a scratch or irritation to the outer layers of the cornea

Cataract-loss of transparency of the lens Glaucoma-increased intraocular pressure Macular degeneration-damage of the macula-

loss of central vision.

Conjunctivitis

Cataract

Central Vision Loss

Peripheral Vision Loss

Refractive Disorders

Focusing problem that occurs when the lens and cornea do not bend light so it focuses properly on the retina.

Astigmatism-impoper focus due to uneven curvatures of the cornea

Hyperopia-(farsightedness) light rays focus beyond retina

Myopia-(nearsightedness) light rays focus in front of the retina

The Ears

Function- receive sound impulses and transmit them to the brain

Auditory-pertaining to the sense of hearing Acoustic-relating to sound or hearing

Major structures

The outer ear-includes the pinna, the external auditory canal, & cerumen.

The middle ear- transmits sound to the inner ear. Includes the tympanic membrane or eardrum.

The inner ear- contains sensory receptors for hearing and balance.

Structures

Common Conditions

Impacted Cerumen Otitis-inflammation of the ear Vertigo- whirling, dizzynesss, loss of balance Tinnitus-a ringing, buzzing, or roaring sound in

ears.

Impacted Cerumen