Physiology Lab: Hearing Flashcards
Name the three parts of the ear.
External ear
Middle ear
Inner ear
What makes up the external ear?
(AKA auricle) - external auditory canal
What makes up the middle ear?
Tympanic cavity that connects with the mastoid cells and nasopharynx
Contains the eardrum membrane and auditory ossicles
What makes up the inner ear?
Cochlea and static labyrinth
Semicircular canals, utricle and saccule
What does the otoscope examine?
External ear and drum
How do you facilitate entrance of the otoscope into the ear?
Auricle is pulled slightly upward, backward and outward
What needs to be removed before looking into the ear with the otoscope?
Debris or cerumen (ear wax)
What is one of the most common conditions that may obstruct the ear and impair hearing?
Excessive or impacted cerumen in the canal
What specific structures can be seen with the otoscope?
Tympanic membrane
Handle of malleus
Chorda tympani crossing the upper part of the membrane
What must be taken note of the tympanic membrane?
Membrane is intact
Normal translucency is present
Drumhead is retracted (middle ear adhesions or bulging towards you - acute otitis media)
Recent or healed perforation of the membrane
Walls of canal
What causes fluid level to be observed through the translucent membrane?
Serious otitis media with infections or with haemorrhage resulting from injury
What effect will acute or chronic external otitis (due to microorganisms - yeast/fungi) have on the walls of the canal?
Excoriation of the walls of canal or external meatus = pain, tenderness, itching, diminution in hearing (skin worn off)
Name the two main classes of deafness.
Conductive Deafness
Sensorineural Deafness ("Nerve" Deafness)What is conductive deafness?
Sound energy cannot pass (i.e. cannot be conducted) from the outer ear to the cochlea
What can cause conductive deafness?
Blockage of external auditory canal, presence of viscous fluid in the middle ear, ossification of the joints between malleus, incus and stapes
What is sensorineural deafness?
Receptors, afferent nerve fibres or CNS pathways are defective
List the three tools to investigate hearing.
Tuning fork
Audiometry
Impedance tympanometry
What is the function of the tuning fork tests?
Discriminate between conductive and sensorineural hearing loss
Name the two tests carried out with the tuning fork.
The Rinne Test
The Weber Test
What does The Rinne test look for?
A defect in the conducting apparatus
Compare the patient’s air conduction and bone conduction
How do you test the patients air conduction in the Rhinne Test?
Tines of the activated fork are placed directly in line with the external auditory canal
How do you test bone conduction in the Rhinne test?
Activated tuning fork on the cortical bone of the mastoid just posterior to the pinna.
Mastoid tip is avoided as it is covered by the insertion of the sternocleidomastoid muscle
What indicates normal hearing/sensorineural hearing impairment?
Air conduction is better than bone conduction.
What indicates a conduction defect?
Bone conduction is better than air conduction
What does the Weber test show?
If hearing in one ear is better than in the other - detect if this unilateral hearing impairment is conduction or sensorineural.
How is the Weber test carried out?
Tuning fork is placed on the patients skull & they should note whether the tone lateralizes (i.e. goes to) a particular side.
Placed on the patients vertex, naison or incisors
Ear in which the tone appears louder is noted
What side does sound laterlise to in a sensorineural hearing impairment?
Non-affected or better side
What side does the sound literalize to in a conductive hearing impairment?
Affected side
- more sound leaks out through the conduction mechanism of the unaffected side
What side does the sound literalize to in a conductive hearing impairment?
Affected side
- more sound leaks out through the conduction mechanism of the unaffected side
What does the audiometer test?
Both your left and right ears for their auditory thresholds at different frequencies
What is an auditory threshold?
Loudness of sound that is audible 50% of the times it is sounded
Varies with the frequency of sound and is at least within the range of 1-3 kHz
What does tympanometry measure?
Determines the acoustic properties of the middle ear - measures how easy it is to make the ear drum vibrate
Tympanic membrane vibrates most when pressures on either side of it are equal
