[W3] The Ears: Hearing Flashcards
What is the function of the pinna (auricle)?
Protects the ear and directs sound waves into the auditory canal.
What is the external auditory meatus?
A 2.5 cm long S-shaped canal with hairs and cerumen to protect against dust/infection.
What is the function of the tympanic membrane?
It vibrates in response to sound waves and transmits them to the middle ear.
What nerves carry pain from the eardrum?
Vagus nerve (CNX) and trigeminal nerve (CNV).
What bones are found in the middle ear?
Malleus, Incus, Stapes (ear ossicles).
What is the function of the auditory (Eustachian) tube?
Equalizes pressure between the middle ear and nasopharynx.
What does the tensor tympani muscle do?
Dampens loud sounds (e.g., chewing); innervated by CNV.
What does the stapedius muscle do?
Reduces vibrations from loud noises; innervated by CNVII.
What structures are part of the inner ear?
Cochlea, semicircular canals, utricle, saccule, and membranous labyrinth.
Which nerve transmits signals from the inner ear?
Vestibulocochlear nerve (CN VIII).
What are the roles of cochlea vs semicircular canals?
Cochlea – hearing; Semicircular canals – balance.
What is audio transduction?
The conversion of sound waves into electrical nerve impulses in the cochlea.
How is amplitude related to hearing?
It determines volume; measured in decibels (dB).
What’s the range of human hearing?
20 Hz to 20,000 Hz.
What happens if exposed to >90 dB for prolonged time?
Damage to sensory receptors in the cochlea may occur.
What starts the hearing process?
Sound waves are directed into the auditory canal and vibrate the tympanic membrane.
How are sound waves amplified?
The ossicles (malleus, incus, stapes) transmit and amplify the vibrations to the oval window.
What fluid receives the pressure waves in the cochlea?
Perilymph in the scala vestibuli.
What causes hair cells in the cochlea to fire?
Movement of the basilar membrane distorts hair cells in the spiral organ.
Where do signals from the cochlea go first?
To the cochlear nucleus in the medulla oblongata.
What structure compares left/right ear input for direction?
Pons.
Where is the startle reflex processed?
Inferior colliculus of the midbrain.
Where is sound consciously perceived?
Primary auditory cortex in the temporal lobe.
What other regions are involved in sound interpretation?
Thalamus (relay), language areas, amygdala (emotion), hippocampus (memory).
