Week 1 - G - Physiology of hearing and balance Flashcards
Which part of the ear is the: Mechanical force amplifier? Sound transducer/analyser? Sound collector?
External ear - sound collector Middle ear - mechanical force amplifier Inner ear - sound transducer/analyser
Approximately, by how much is the sound amplified from when it hits the tympanic membrane to when it reaches the oval window?
Amplified by about 22 fold
What is the primary and secondary function of the Eustachian tube?
Primary function - to ventilate ears ensuring its pressure remains at a normal environmental pressure Secondary function - to drain accumulation of any fluid/infection from the middle ear space
What are the two openings of the cochlea known as?
The oval window - where sound enters from the middle ear The round window - where pressure waves are dampened in the inner ear
What does the vibrations of the cochlea happen along?
Happens along the basilar membrane (contains the organ of corti)
How many turns are in the cochlear apparatus?
2.5 turns
What is the endolymph suspended in, in the cochlea? What is on either side and what ligament suspends it?
Endolymph is suspended in the scala media (cochlear duct) suspended in between scala vestibuli (superiorly) & scala tympani (inferiorly) (perilymph) The spiral ligament suspends the cochlear duct
Where does the cochlear nerve insert at to receive the signal for hearing?
Inserts at the organ of corti - this structure contains hair cells which are responsible for converting soundwaves into neural signals
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The auditory nerve inserts at the pontomedullary junction and then the impulses travel to the superior temporal gyrus
Stereocilia is found in the ampulla of semicircular canals Where is the sterocilia found in saccule and utricles?
Found in the maculae
What sits in the middle of the ampulla of the semicircular canals?
Cupula - deflection of the cupula is caused by the movement of perilymph in the semicircular canals
What direction does the cupula (ampulla) go when the head moves right? (or left) What direction do the eyes move in? What is this reflex known as?
The cupula push the opposite direction of head movement The eyes also move to the opposite direction of head movement This preserves the image on the center of the visual field This is the vestibulo-occular reflex
What condition can damage to the vestibulo-occular eflex cause? It is known as dancing eyes
Nystagmus (can also be caused by BPPV and albinism)
Nystagmus is a condition of involuntary eye movement, acquired in infancy or later in life, that may result in what defect to the vision?
Can cause reducedd or limited vision
