ch 13: organs and anatomic structures of the ear

ear

organ of hearing and balance

external ear

consists of the auricle and external auditory canal (meatus)

auricle

external, visible part of the ear located on both sides of the head; directs sound waves into the external auditory canal

external auditory canal

short tube that ends at the tympanic membrane. The inner part lies within the temporal bone of the skull and contains the glands that secrete earwax (cerumen)

middle ear

consists of the tympanic membrane and the tympanic cavity containing the ossicles

tympanic membrane

semitransparent membrane that separates the external auditory canal and the middle ear cavity. transmits sound vibrations to the ossicles

ossicles

bones of the middle ear that carry sound vibrations. composed of the malleus (hammer), incus (anvil), and stapes (stirrup). the stapes connects to the oval window, which transmits the sound vibrations to the cochlea of the inner ear

eustachian tube

passage between the middle ear and the pharynx; equalizes air pressure on both sides of the tympanic membrane

inner ear

consists of the labyrinth and connectors of the vestibular and the cochlear nerves

labyrinth

bony spaces within the temporal bone of the skull made up of three distinct parts, the cochlea, the semicircular canals, and the vestibule. the cochlea facilitates hearing. the semicircular canals and the vestibule facilitate equilibrium and balance

cochlea

coiled portion of the inner ear containing the sensory organ for hearing; connects the oval window in the middle ear

semicircular canals and vestibule

sensory organs of balance; contain receptors and endolymph that provide sensory information about the body’s position to maintain equilibrium

vestibulocochlear nerves

paired cranial nerves responsible for hearing and balance; composed of vestibular fibers and cochlear fibers

vestibular nerve

conveys information about position and balance from the semicircular canals and vestibule to the brain

cochlear nerve

conveys information about sound, including volume and frequency, from the cochlea to the brain

mastoid bone

portion of the temporal bone of the skull posterior and inferior to each auditory canal; contains mastoid air cells that drain into the middle ear cavity behind the external auditory canal