Physiology of hearing and balance Flashcards
Which properties of sound dictate pitch and intensity?
Frequency and amplitude
What frequencies of sound can humans perceive?
20Hz-20000Hz
What roles do the external, middle and inner ear play respectively in hearing?
Reciever, signal amplifier and transducer
What happens when sound waves hit the tympanic membrane?
Cause displacement of the auditory ossicles
What are the names of the auditory ossicles?
Malleus, incus and stapes
How is a pressure wave established within the perilymph of the vestibular duct?
Movement of stapes against the oval window of the cochlea
What causes hair cells to depolarise?
Vibration of the basilar membrane causes cilia of hair cells to vibrate against the tectorial membrane, causing depolarisation by influx of potassium ions from the endolymph
How are intensity and frequency of sound determined by the organ of Corti?
Intensity relates to number of hair cells stimulated; frequency relates to the region of maximum distortion of the basilar membrane
Where is the primary auditory complex located?
Superior temporal gyrus, Brodman areas 41/42
What is the pathway of signals from the cochlea to the auditory complex?
Cochlear branch of CN VIII; vestibulocochlear nerve (CN VIII); cochlear nucleus in the brainstem; inferior colliculi; medial geniculate nucleus proximal to the thalamus; audtitory cortex
What is the role of the vestibular complex?
Balance and equilibrium sensations
What are the five key vestibular end-organs?
MACULAE of the utricle and saccule; AMPULLAE of the lateral, posterior and superior semicircular canals
What information do the semicircular canals and otolith organs respectively convey?
Rotational movements of the head; linear motion and acceleration of the head
What is a cupula?
Gelatinous structure overlying the hair cells of the semicircular canals
How are hair cells within the semi circular canals stimulated?
Movement of perilymph causes the cupula to move, thus moving the hair cells
