The outer part of the ear is called the auricle and contains mostly fat and cartilage. The hole going into the ear is called the external acoustic meatus and extends into the eardrum (tympanic membrane). The middle ear or tympanic cavity contains the auditory ossicles (bones) and tympanic muscles and extends to the inner ear, containing the cochlea, vestibule, and semicircular canals (control equilibrium). The cochlea is spiral-shaped and contains an oval window, round window, organ of corti, vestibular duct, cochlear duct, tympanic duct, basilar membrane, tectorial membrane, hair cells, and nerve fibers. The vestibule contains the utricle and saccule which contain maculae, crystals that help verify the position of the head. This lecture also explains how soundwaves travel through the ear as well as different diseases and conditions.
The external ear includes the auricle (pinna), external acoustic (auditory) meatus, hair, ceruminous glands, and the tympanic membrane (eardrum)
The middle ear contains the middle ear bones: malleus, incus, and stapes (hammer, anvil, and stirrup), and muscles associated with them
The inner ear contains the boney labyrinth (cochlea, vestibule, and semicircular canals)
The cochlea is filled with various ducts (vestibular/cochlear/tympanic) and membranes (basilar/tectorial) that help transfer vibrations into electric signals in hair cells
Sound waves hit the tympanum, vibrating the auditory ossicles to amplify the sound, which hits the oval window and moves the fluid/membranes within the cochlea to stimulate hair cells, which send their signals to the brain through the cochlear nerve
Sound is measured in Hz for frequency (pitch) and decibels for loudness (amplitude)
The vestibule contains the utricle and saccule (each one has a macula), which are needed for telling the brain how your head is oriented in space
The semicircular canals have ampullae that are analogous to the three dimensions in space and their relative movements tell the brain how your head is rotating in space
Hearing conditions/disorders include tinitis, motion sickness, and ear infections
Did you know…
Q: What does the round window of the cochlea do?
A: The round window, which is inferior to the oval window, allows sound waves to dissipate out of the cochlea
Q: Is it true that you’re not supposed to use cotton swabs (Q-Tips) to clean out your earwax?
A: It is recommended that you do not use Q-Tips. It’s possible to do worse damage, such as pushing wax (cerumen) further against the tympanum, or even damaging/puncturing the tympanum! There are other ways to clean out your ears without putting a long hard object into your ear canal.
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
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