Structures and Functions of the Ear

TABLE 11—2 STRUCTURES AND FUNCTIONS OFTHE EAR
ORGAN OR STRU URE FUNCTION
External Ear
Auricle or pinna Cartilaginous projection that collects and directs sound waves into the auditory
canal, much like a satellite dish collects transmissions from space
Auditory canal or external auditory Canal responsible for conduction of sound that contains earwax, or cerumen,
meatus secreted by the ceruminous glands to lubricate the canal and trap foreign particles
Eardrum or tympanic membrane Membrane that separates the external and middle ear
Middle Ear
Ossicles Three small bones (malleus, incus, stapes) that help amplify and transmit sound
Eustachian tubes Allows for equalization of external (atmospheric) and internal (within the middle
ear) pressure on the tympanic membrane so the eardrum can freely vibrate with
incoming sound
Inner Ear or Labyrinth
Cochlea Bony, snail-shaped entrance to the internal ear containing perilymph fluid, which
helps to transmit sound
Semicircular canals Three canals containing endolymph fluid, which transmits positional changes to
tiny, hairlike receptors that are stimulated and conduct the signal to the brain via
the vestibulocochlear nerve (eighth cranial nerve) to help maintain balance