Special Senses
Ears
Chapter 15
Objectives:
O Identify the primary functions of the
Ear
O Introduce some medical words related
to the Ear
O Identify and define some selected
abbreviations related to the Ear
Ear:
O One who specializes in the study of hearing
is :
O Audiologist
Ear:
O The ear is the organ that detects
sound
O It also helps provide balance and
equilibrium
O consists of outer, middle, and
inner parts
External (outer) ear:
O is the most external portion of
the ear
O consists of the visible portion on
the side of the head, known as
the pinna and the external
auditory canal or ear canal.
Contd:
O Pinna: (also called the auricle) the
visible part of the outer ear. It collects
sound and directs it into the outer ear
canal
O External ear canal: the tube through
which sound travels to the eardrum.
(tympanic membrane)
Contd:
O The ear drum is about 1 ¼ inches
long
O Contains modified sweat glands
O Sweat glands secrete Cerumen (Latin
word for ear wax)
O Too much Cerumen can block sound
transmission
Word Building:
O Auricle
O Aur/i
O -cle
ear
small thing
O Pinna
O Latin word meaning wing or fin
Contd:
O
O
O
O
anacusis
anwithout, absence of
-acusis
hearing condition
Total hearing loss
O
O
O
O
otalgia
ot/
ear
-algia
pain
Pain in the ear, earache
Middle Ear:
O located between the outer ear and the inner
ear and consists of the following parts :
O Eardrum - The eardrum, also known as
tympanic membrane is a thin membrane
that acts as a partition between the outer
ear and the middle ear.
O Has three small bones or ossicles that are
important for hearing.
Contd:
O Hammer (Malleus) - It is a tiny bone, located
next to the eardrum. Since it lies adjacent to
the eardrum, the vibrations from the eardrum
cause the hammer to vibrate.
O Anvil (Incus) - Anvil is another tiny bone next to
hammer; it vibrates in response to the
vibration of hammer.
O Stirrup (Stapes) - Similar to hammer and anvil,
stirrup is a tiny bone in the middle ear;
eventually, it also vibrates and passes the
compressional waves to the inner ear.
Inner Ear:
O is the innermost portion of the ear.
O It is filled with a water-like substance and
comprises both hearing and balancing
organs.
O Consists of a maze like network of canals
located within a bony labyrinth
O The bony labyrinth comprises the
following parts:
Contd:
O Cochlea - or the spiral tube is a rolled structure
that can stretch to about 3 cm;
O the membrane lining of cochlea consists of
numerous nerve cells. The hair-like nerve cells
respond differently to various frequencies of
vibrations, which ultimately lead to generation of
electrical impulses.
O Semicircular Canals - These are fluid-filled loops,
attached to the cochlea and helps in maintaining
the balance.
O Auditory Nerve - The electrical impulses,
generated by the nerve cells, are then passed to
the brain
Process of Hearing:
O Outer Ear - captures sound waves and guides them into the
ear canal
O Ear Canal - carries the sound waves towards the eardrum
O Eardrum - (tympanic membrane) vibrates from the sound
waves
O Middle Ear Bones - (malleus, incus and stapes) pick up
vibration from the eardrum
O Cochlea - as vibrations pass through this organ, the fluid
inside the cochlea moves, causing thousands of "hair cells" to
set in motion so they can translate the sound waves into
electrical impulses
O Auditory Nerve - sends the electrical impulses to the brain to
be processed as sound
Common abbreviations:
O AC
O AD
O AS
O AU
O BC
O HD
O ENT
O OM
Air conduction
Right ear
Left ear
Both ears
Bone conduction
Hearing distance
Ear, nose and throat
Otitis media
Medical Vocabulary:
O acoust/
hearing
O -ic
pertaining to
O Pertaining to the sense of hearing
O Acoustic
O audi/o
to hear
O -gram
a mark, a record
O A record of hearing
O audiogram
Contd:
O equilibrium
O Pertaining to the sense of balance
O deafness
O Complete or partial loss of the ability to
hear
O tinnitus
O The sensation of ringing in one or both ears
O vertigo
O Sensation of loss of equilibrium
Medical instrument used to
examine the eardrum
O myring/o
O eardrum (TM)
O -scope
O Instrument for
examining
O myringoscope
Special Senses
Eyes
Chapter 16
Objectives:
O Identify the primary functions of
the eye
O Introduce Medical words related
to the eye
O Identify selected abbreviations
Ophthalm/o
eye
-logy
study of
Ophthalmology
Study of the eye
O Opthalmologist
O opthalm/o eye
O -logy
O
O
O
O
O
O
O
study of
-ist
one who studies
Physician who specializes in the study of the
eye
Optometrist
opt/o
eye
metr/
measure
-ist
one who specializes
One who specializes in examing the eye
Eyes:
O Most important sense organ
O Located in the orbit (bony
protective cavity of the skull)
O The eye lets light in, focuses it,
transforms it into nerve impulses,
then sends them to the brain
Contd:
O Light passes through the cornea, pupil, lens and
O
O
O
O
O
the vitreous body to rods and cones ( sensory
receptors) in the retina
Vision is made possible by:
the coordinated actions of the nerves that
control the eyeball
The amount of light admitted by the pupil
The focusing of light on the retina by the lens
And the transmission of the image to the brain
Parts to the eye:
O The eye consists of the inner eye
(eye ball)
O And the outer eye ( the facial
structures and eye muscles
surrounding the eye)
External Structures of the eye:
O Orbital cavity: bony depression that the
eyeballs fits into
O Ocular muscles: attach to the sclera and
move the eye
O Eyelids: shield the eye from light, dust and
trauma by blinking
O Blephar/o
eyelid
O Conjunctiva: lines the eyelids and protects
and lubricates the eye
Contd:
O The eyelids protect the eyes, shade
eyes during sleep, and spread
lubricating fluid.
O The term DACYR/O is used to
denote tears.
O This lubricating fluid comes from
three areas:
Contd:
O LACRIMAL GLANDS located above the
outer corner of each eye
O LACRIMAL DUCTS which drain gland
secretions into the lacrimal sacs.
O Lacrim/o
tears
O -al
pertaining
Internal Structures of the Eye
O Eyeball:
O Organ of vision
O Two cavities:
O ocular cavity = space in front of lens has
O
O
O
O
O
aqueous humor
aque/o
watery substance
-ous
pertaining to
Posterior cavity = larger cavity has vitreous
humor
vitre/o
transparent substance
-ous
pertaining to
Inner Eye:
O Made up of three layers: Outer, Middle and Inner
O The outer layer contains:
O Cornea: (latin word) is the transparent anterior
portion of the eye
O Sclera: (scler/o hard) is the white of the eye.
Providing a protective covering for the eyeball
Contd:
O Middle layer: (uvea)- latin word means
grape
O Choroids: inner lining of the sclera.
Contain blood vessels that nourish the eye
O Ciliary muscles: muscles that adjust the
shape of the lens for focusing. This
produces a watery substance aqueous
humor.
O cili/o
hairlike structure
O -ary
pertaining to
Middle Layer Contd:
O The iris is a thin diaphragm composed
mostly of connective tissue and smooth
muscle fibers.
O The opening in the iris is the pupil
O The color, texture, and patterns of each
person’s iris are as unique as a
fingerprint.
Contd:
O Inner Layer:
O Retina: has layers of nervous tissue
called cones and rods
O Vitreous humor: jelly like matter in
the back of the eye. (80% of eye
volume)
O This preserves the shape of the
eyeball
Contd:
O Lens:
O A clear flexible disk behind the pupil
O Contains protein molecules in a
crystalline structure
O Function is to sharpen the focus of light
on the retina
O accommod/o
to adapt
O -ation
a process
O accommodation
Process of vision:
O Light waves from an object (such as a
tree) enter the eye first through the
cornea,( the clear dome at the front
of the eye)
O The light then progresses through
the pupil.
O Fluctuations in incoming light change
the size of the eye’s pupil
Contd:
O The light continues through the
vitreous humor,
O then, ideally, back to a clear focus on
the retina, (the retina is equivalent to
the film inside of a camera, registering
the tiny photos of light interacting with
it).
Contd:
O Within the layers of the retina, light
impulses are changed into electrical
signals.
O Then they are sent through the optic
nerve, along the visual pathway, to the
occipital cortex at the posterior (back) of
the brain.
O Here, the electrical signals are interpreted
or “seen” by the brain as a visual image.
Common abbreviations:
O OD
Right eye
O OS
Left eye
O OU
Each eye
O PERRLA Pupils equal, round, and
reactive to light and accommodation
O VA
Visual acuity
O VF
Visual field
Contd:
O Dirty contact lenses can cause a severe
infection called KERATITIS.
O Rupture of the cornea is known as
KERATORRHEXIS.
O The cornea is incised with an instrument
known as a KERATOMTOME.