OS III, Ex II, auditory lecture 1 Flashcards
What are the 3 parts of the inner ear?
External, middle, inner
Parts of external ear?
auricle, ceruminous glands
Auricle is made of what?
elastic cartilage and sking
Parts of auricle?
helix, antihelix, tragus, antitragus, concha and lobule
What are ceruminous glands?
modified apocrine glands that secrete cerumen
What is ear wax?
combo of cercumen, sebacous gland secreation, and desquamated meatal cells
what are the external ear sebaceous glands associated with?
hairs
What nerves innervate the external ear and external acoustic meatus?
greater auricular, lesser occipital, auriculotemporal, facial and vagus
What innervates middle ear?
glossopharyngeal
what connects tympanic cavity to nasopharynx?
auditory tube
What opens the tubal cartilage?
levatory tensor paliti, and salpingopharyngeus
what are used to amplify vibrations from membrane to oval window?
ossicles, malleus, incus, stabes
Oval window leads to where?
cochlea
What muscles are activated to dampen vibrations through ossicles?
tensor tympani: low frequency, stapedius: extream stapes vibrations
What innervates the tensor tympani?
V3 - trigenimal
What innervates stapedius?
VII - facial
What is the chorda tympani?
Both a sensory and autonomic nerve that branches from facial VII to V#
What nerve has sensory neurons that mediates taste from front of tongue?
Chorda tympani off the facial nerve
What do the parasympathetics from the chorda tympani innervate?
Submandibular and sublingual salivary glands.
Why may the corda tympani be impacted by otitis media, ear infection of middle ear?
because it passes between tympanic membrane and malleus, the first ossicle
what is the center depression of tympanic membrane called?
umbo, its caused by malleous tension
What should you be able to see if looking at ear drum auriscopically?
malleus, incus, stapes, cone of light, tence and flacid parts
What can caouse otitus media?
Fluid buildup that blocks middle ear, negative pressue that pulls bacteria/virus up from pharynx.
What could an invection of middle ear do?
perforate tympanic membrane, then spread through tegmen tympani cause brain abcss or meningitis.
What conditon damages middle ear an mastoid by growing out of control?
Cholesteatoma
What is choleasteaoma?
ear canal skin fills with cysts that migrate through porforation of tympanic membrane.can erode ossicles.
what part of inneer has the hearing receptors?
Cochlea
What is chochlea?
fluid filled spirally formed bony canal
What are the three parts of cochlea?
Chochlear duct (scala media) scala vestibuli (top), scala tympani (bottom)
What is the fluid of the cochlear ?
endo lymph that is screated by stria vascularis is in the cochlear duct while Periymph is in the scala vestibuli and tympani which are continuous.
Endolymph is high in what ion?
K + - potassium
Perilymph is high in what ion?
Na+
what encloses the organ of corti?
Cochlear duct ie scala media
What does the oval window vibration come in contact with?
the scalia vestibula and its perilymph that eventually becomes scalia tympani on its way to the round window.
What is the sound tranduction for each part of ear?
External - air, Middle, Bone vibration, Inner - fluid vibration
What laye does the organ of corti form on?
basilar membrane, an epithelial layer
What covers organ of corti?
tectoral membrane
what are the types of non-neural receptor cells?
both innner and outer hair cells
What comes in contact with the tectoral membrane from the organ of corti?
stereocilia/microvili that activate sensory neurons of choclhelar nerve
What causes bend in the sterreocilia part of receptors?
sound waves and their vertical oscilations of the basilar membrane.
How does distortion of stereocilia produce hearing?
Distortion produce depolarization that causes release of transmitter to sensory neurons.
What contains cell bodies of sensory neurons of the cochlear nerves?
spiral gnaglion
How are tones differentiated ?
by the difference in basilar membrane stiffness and width. Narrow is stiff and detects high frequency while the further away membrane is wide and flexable and detects low frequencys.
How does the difference in membrane stiffness detect specific sound.
sound frequency will only vibrate membrane at max amplitued in specific spots
What do 95% of the sensory neuron axons in the cochlear nerve innervate?
inner hair cells, while the other 5% innervate outter hair cells.
What do inner hair cells respond to?
basilar membrane movements at specific frequencies
So what do outter hair cells do?
enhance weak auditory signals transduced by inner hair cells.
What happens to outer hair cell in response to bending?
electromitile contraction followed by elongations, recoil amplifies.
What type of feedback does the outer hair cell uses?
positive feedback
What leads to hearing loss?
loud noise that damages outer hair cells.
What increases our ability ito distinguish between frequencys that are close together?
outer hair cells, they sharpen sound peak from dull and rounded
What is the primary auditory path?
Auditory nerve from cochlea - dorsal/ventral cochlear nuclei in medulla
How many paths from medullary cochlear nuclei?
dorsal cochlear nucleus (red) and the ventral cochlear nucleus (black olive)
what nuclei detects quality of sound so can distinguish between similar dounds?
red dorsal cochlear nucleus
What does the superior olive ventral cochlear nucleus do?
Localizations
Path from either the dorsal cochlear or the ventral cochlear?
up to lateral leminiscus, inferior colliculus, medial geniculate, primary suditory cortex in temp lobe.
what localizes low frequencies?
time difference
What localizes high frequency?
intensity
What is the inferior colliculus for?
somatosensory for head orientation for sound localization.
what does the medial geniculate body of thalamus do?
project sound. To cortex tonotopically, high frequency medial, low freq lateral.
Where is the primay auditory cortex?
superior temporal lobe
two streams of auditory association cortex
Ventral - speech comprehension, and dorsal - sensory motor for vocal artuculation.
Ventral stream of auditory association cortex is for what?
comprehension of voice, language etc, wernikes area
Wernikes area is for what?
Understanding speech : integrate auditory visual and somatosensory aspects of language
What parts of written word are most importaint?
first and last letter, brain wil figure out the rest.
What are involved in higher levels of auditory activity?
bilaterally, tenporal paretal and motor cortices.
What is most involved in specific sides of brain?
singing is more right
How does music in auditory cortex cause emotion?
It effects limbic regions: amygdala, cingulate cortex, hippocampus and insula
what regulates outer and inner hair cells to regulate sensitivity to sound especially at low leves
Efferent olivochochlear nerurons from superior olive
what would help supress background noise?
olivochochlear efferents
what stimulates efferent olivarycochlear efferents?
input from cochlear nuclei, reticular formation, auditory cortex
two types of deafness
conductive - tympanic membrane, sensorineural - damage to cochlea or cochlear portin of VIII
What is subjective tinnitus?
sound sinsation without external stimulation.
Broad Causes of tinnitus?
abnormal neural activity in path, change in primary auditory cortex,
more specific causes of tinnitus
disease process, TMJ, neurological damage, infections, drug side effects.
two types of tinnitus?
subjective and somatic
What is somatic tinnitus
specific type of subjective, with 2 or more causes
What can cause somatic tinnitus?
trigeminal relays afferent info, can send excitary projections.
