THE EAR AND HEARING Flashcards
what is humans frequency range for sound?
20-20,000 Hz
what is the part of the ear we can see called?
the pinna aka auricle
what is the name of the ear canal?
external auditory meatus
whats the name of the ear drum?
the tympanum
whats the function of the pinna?
to funnel sound into thr external auditory meatus and filters sounds
in other mammals what other roles does the pinna have?
signalling mood and assisting with thermoregulation
outline the structure of the external auditory meatus?
a sigmoid shaped tube that extends from the deep part of the concha to the tympanic membrane. The walls of the external 1/3 are formed by cartilage, whereas the inner 2/3 are formed by the temporal bone.
the tympanic membrane is a concave structure, what do we call the most depressed region?
the umbo - also where the handle of the malleus attached
whats the function of the tympanum?
vibrate in response to sound pressure waves and thus transmit sound energy into the middle ear
whats the blood supply of the external ear?
posterior auricular branch of the external carotid artery.
what nerves innervate the skin of the auricle?
greater auricular nerve
lesser occipital nerve
auriculotemporal nerve
what innervates the external auditory meatus?
auriculotemporal nerve and branches of facial and vagus nerves
what inervates the deeper aspect of the auricle?
branches of facial and vagus nerves
why do some individuals complain of an involuntary cough when cleaning their ears?
due to stimulation of the auricular branch of the vagus nerve which is also responsible for the cough reflex
what is within the middle ear?
ossicles and eustachian tube
whats the function of the ossicles?
transmit sound and amplify it
what are the 3 ossicles?
malleus (hammer)
incus (anvil)
stapes (stirrup)
why are mammals much better at hearing than birds?
as mammals have 3 ossicles and birds have 1
whats the function of the Eustachian tube?
to allow pressure equilisation between middle ear and outside world - important to prevent damage to tympanic membrane
how can you open the Eustachian tube?
lower and protrude the jaw
what are the 2 middle ear muscles and where do they attach?
tensor tympani attaches to malleus
strapedius atached to the stapes
whats the function of tensor tympani and stapedius muscles?
pulls the eardrum inward and decreases the area over which sound energy may be collected. = acoustic reflex
what is the acoustic reflex?
the contraction of the stapedius muscle elicited by the presentation of an acoustically loud sound
what is tensor tympani innervated by?
branch of mandibular nere
what is the stapedius muscle innervated by?
facial nerve
whats the 2 main functions of the inner ear?
converting mechanical signals from the middle ear into electrical signals
to maintain balance by detecting position and motion
where is the inner ear located?
in the petrous part of the temporal bone
what are the 2 main components of the inner ear?
bony labyrinth and membranous labyrinth