Chapter 13

By: Norma GongoraBy: Norma Gongora

Chapter 13 Chapter 13 Special senses: The Eye Special senses: The Eye

and Earand Ear

Anatomy and Physiology Relating Anatomy and Physiology Relating to the Eyeto the Eye

The study of the eye is ophthalmology.The study of the eye is ophthalmology. The eyeballThe eyeball is the incredible organ of is the incredible organ of

sight that transmits an external image by sight that transmits an external image by way of the nervous system—the optic way of the nervous system—the optic nerve—to the brain. nerve—to the brain.

Also included are the eye muscles, eyelids, Also included are the eye muscles, eyelids, conjunctiva, and lacrimal glands and conjunctiva, and lacrimal glands and ducts.ducts.

The EyeballThe Eyeball

Eyeball is composed of three layers: Eyeball is composed of three layers: ScleraSclera ChoroidChoroid RetinaRetina

ScleraSclera

The outer layer, the sclera, provides The outer layer, the sclera, provides a tough protective layer for the inner a tough protective layer for the inner structures of the eye. Another term structures of the eye. Another term for the sclera is the white of the eye.for the sclera is the white of the eye.

CorneaCornea

The anterior portion of the sclera. The anterior portion of the sclera. Clear, transparent part of the sclera.Clear, transparent part of the sclera. Allows light to enter the interior of Allows light to enter the interior of

the eye. the eye.

ChoroidChoroid

Second layer or middle layer of the Second layer or middle layer of the eye. eye.

This layer provides the blood supply This layer provides the blood supply for the eye and is opaque.for the eye and is opaque.

RetinaRetina

Contains the sensory receptor, rodsContains the sensory receptor, rods,, and cones .and cones .

Rods are active in dim light and help Rods are active in dim light and help us to see in black and white. us to see in black and white.

Cones are active only in bright light Cones are active only in bright light and are responsible for color visionand are responsible for color vision..

Muscles of the EyeMuscles of the Eye

There are six muscles that connect There are six muscles that connect the actual eyeball to the skull.the actual eyeball to the skull.

These muscles change the direction These muscles change the direction each eye is looking in. each eye is looking in.

They provide support for the eyeball They provide support for the eyeball in the eye socket. in the eye socket.

EyelidsEyelids

Over each eyeball.Over each eyeball. Provide protection from foreign particles, Provide protection from foreign particles,

injury from the sun and intense light, and injury from the sun and intense light, and trauma. trauma.

Both the upper and lower edges have Both the upper and lower edges have eyelashes or ciliaeyelashes or cilia that protect the eye that protect the eye from foreign particles.from foreign particles.

Sebaceous glandsSebaceous glands located in the eyelids located in the eyelids secrete a lubricating oil onto the eyeball. secrete a lubricating oil onto the eyeball.

ConjunctivaConjunctiva

A mucous membraneA mucous membrane lining. lining. Forms a continuous covering on the Forms a continuous covering on the

underside of each eyelid and across underside of each eyelid and across the anterior surface of each eyeball.the anterior surface of each eyeball.

Serves as a protection for the eye.Serves as a protection for the eye.

Lacrimal GlandLacrimal Gland

Located in the outer corner of each Located in the outer corner of each eyelid. eyelid.

These glands produce tears. These glands produce tears. Tears serve the important function of Tears serve the important function of

washing and lubricating the anterior washing and lubricating the anterior surface of the eyeball. surface of the eyeball.

This duct ultimately drains the tears into This duct ultimately drains the tears into the nasal cavitythe nasal cavity..

Anatomy & Physiology of the EarAnatomy & Physiology of the Ear

Study of the ear is referred to as Study of the ear is referred to as otology (Oto).otology (Oto).

Study of hearing disorders is called Study of hearing disorders is called audiology. audiology.

The ear is responsible for two senses: The ear is responsible for two senses: • Hearing Hearing • Equilibrium or our sense of balance Equilibrium or our sense of balance

The Ear Subdivided into Three The Ear Subdivided into Three AreasAreas

The external earThe external ear The middle earThe middle ear The inner earThe inner ear

External EarExternal Ear

The auricle or pinnaThe auricle or pinna is the only portion is the only portion visible; with its earlobe has a unique shape visible; with its earlobe has a unique shape in each person and functions like a funnel in each person and functions like a funnel to capture sound waves as they go past to capture sound waves as they go past the outer ear.the outer ear.

Auditory canalAuditory canal where sound then moves where sound then moves along along

CerumenCerumen is produced in oil glands in the is produced in oil glands in the auditory canal. auditory canal.

The Middle EarThe Middle Ear

Located in a cavity in the temporal Located in a cavity in the temporal bone of the skullbone of the skull

Vital to the hearing processVital to the hearing process

The Inner EarThe Inner Ear

Located in a cavity within the Located in a cavity within the temporal bone referred to as the temporal bone referred to as the labyrinth labyrinth

Contains the hearing and equilibrium Contains the hearing and equilibrium sensory organs: sensory organs: • Cochlea Cochlea • Semicircular canalsSemicircular canals• UtricleUtricle• SacculeSaccule