Lecture 4: Ears Flashcards
Learning Objectives
Learn structure and function of the ears
Learn the methods of examination of hearing and external ear structures
Record the assessment accurately
Structure and Function
Sensory organ for hearing
Maintains equilibrium
Healthy ears are essential to effective communication and balance
Three parts:
External Ear
Middle Ear
Inner Ear
External Ear
Auricle or Pinna
- Movable cartilage and skin
- Funnels sound waves
Auditory canal
- 2.5 to 3 cm long in adults
-Slight S-curve in adult
- Lined with glands that secrete cerumen
Prevents foreign bodies from reaching sensitive TM
Middle Ear
-Air-filled cavity inside temporal bone
- Auditory ossicles (tiny bones)
*Malleus, incus, and stapes
Three functions
1. Conducts sound vibrations from outer ear to central hearing apparatus
2. Protects inner ear by reducing amplitude of sounds
3. Eustachian tube allows equalization of air pressure on each side of TM so that it does not rupture
Tympanic Membrane
Separates external and middle ear
Translucent, pearly gray
Oval and slightly concave
Eustachian Tube
opening that connects middle ear with nasopharynx and allows passage of air
Normally closed, but opens with swallowing or yawning
Infant- shorter, wider and horizontal- easy for pathogens to migrate from nasopharynx to the middle ear- Otitis Media (Ear Infection)
Adult- sloped- harder for pathogens to migrate
Inner Ear
Contains the bony labyrinth: holds sensory organs for equilibrium (balance) and hearing
The inner ear is not accessible to direct examination
- but we can assess its functions
Pathways of Hearing
Normal pathway of hearing: air conduction (AC)
- most efficient
Alternate route: bone conduction (BC)
-Bones of the skull vibrate –> transmit to inner ear/CN VIII
Hearing loss:
- Anything obstructing transmission of sound
Conductive Hearing Loss
involves a mechanical dysfunction of external or middle ear
- impacted cerumen
foreign bodies - perforated TM
- Purulent ((from infection)) or serous fluid in middle ear
- otosclerosis: a decrease in mobility of ossicles of the bones
Sensorineural Hearing Loss
signifies pathology of inner ear, cranial nerve VIII, or auditory areas of cerebral cortex
presbycusis:
gradual nerve degeneration that occurs with aging
ototoxic drugs, which affect hair cells in cochlea
Mixed Hearing Loss
combination of conductive and sensorineural types in same ear
Ear Equilibrium
Labyrinth in inner ear constantly feeds information to brain about body’s position in space
- Determine verticality and depth
- Registers angle of head in relation to gravity
- If labyrinth becomes inflamed, it feeds wrong information to brain, creating a staggering gait and a strong spinning, whirling sensation called vertigo
Subtle cues that could possibly indicate hearing loss
Lip reading or watching your face and lips rather than your eyes
Frowning or straining forward to hear
Posturing of head to catch sounds with better ear
Misunderstands questions; frequently asks you to repeat
Irritable or shows startle reflex when you raise your voice
Person’s speech sounds garbled, vowel sounds distorted
Inappropriately loud voice
Flat, monotonous tone of voice
Subjective Data - Health History
Otalgia (Earache)
Infection
Discharge
Hearing loss
Environmental Noise
Tinnitus (ringing in the ears)
Cerumen (ear wax)
Vertigo (true spinning motion)
Self-care : Cleaning ears (Q tips vs. pinky with soap)
Hearing checked
Medications (taking antibiotics?)
Family History
Physical Exam Equipment
Otoscope with bright light
Tuning forks in 512, 1024 Hz
(High pitched)
Developmental Competence
top of the pinna should be an imaginary line extendending from the corner of the eye to the occiput
lowset (greater than 10%)
ears are found with alcohol syndrome or genetic disorders: trisomy 13, 18, 21 (down syndrome)
Inspect and Palpate: External Ear
Size and shape:
equal
Skin:
Consistent with facial skin color
Tenderness:
Auricle
Tragus
mastoid
External auditory meatus:
Use largest speculum that will fit
Position head away from examiner
Can hold the otoscope up or down
Pinna positioning
Hold pinna gently but firmly
Pull pinna up and back on an adult or older child to straighten S-shape of canal
-Pull pinna down on an infant and a child under 3
*infant’s and young child’s external auditory canal is shorter and has a slope opposite to that of adult’s
Otitis Media
Pathways of Hearing Recap/Diagram
Sound vibrations traveling through air are collected by and funneled through the external ear causing the eardrum to vibrate.
Sound waves are then transmitted through auditory ossicles as the vibration of the eardrum causes the malleus, the incus and then the stapes to vibrate.
As the stapes vibrates at the oval window, the sound waves are passed to the fluid in the inner ear.
The movement of this fluid stimulates the hair cells of the spiral organ of Corti
initiates the nerve impulses that travel to the brain by the way of the acoustic nerve, CN VIII.
Weber Test
Place vibrating tuning fork midline on top of person’s skull:
Can use forehead if unable to hear
Normal-sound heard equally both ears
Abnormal-sound heard only one side
Conductive v. Sensorineural
-Strike tines of tuning fork and place on the center of the head or forehead.
-Ask whether the client hears the sound better in one ear or the same in both ears
Normal- sound heard equally well in both ears and no lateralization of sound to either ear
Abnormal-
Conductive hearing loss- client reports lateralization of sound to the poor ear- good ear distracted by background noise and conducted air, which poor ear has trouble hearing, receiving sound conducted by bone
Sensorineural hearing loss- client reports lateralization of sound to the good ear- nerve damage in bad ear
Rinne Test
Strike tuning fork
Place on mastoid until unable to hear
Then place tines in front of external auditory meatus
Be sure to time hearing
Test both ears
Normal: heard twice as long by air conduction or AC as bone conduction or BC
Cause of Hearing Loss:
Strike tines of tuning fork and place the base on the client’s mastoid process (BC)
When the client no longer hears the sound, note the time interval, and move the tuning fork in front of the external ear (AC) When the client no longer hears the sound, note the time interval.
Normal AC>BC usually 2:1
Used to determine cause of hearing loss (conduction or sensorineural) once it is determined that there is a hearing loss.
Sensorineural- AC>BC, if anything is heard
Conductive- BC> or = to AC
