medterm ch 13 - ear

2 functions of the ear

hear and balance

external ear includes

auricle and external auditory canal/meatus

auricle

external, visible part of the ear

• directs sound waves into external auditory canal

• aka pinna

external auditory canal / meatus

short tube that ends at tympanic membrane

• inner part lies within temporal bone of skull and contains the glands that secrete earwax (cerumen)

middle ear consists of

tympanic membrane and tympanic cavity containing ossicles

tympanic membrane

semitransparent membrane that separates the external auditory canal and middle ear cavity

• transmits sound vibrations to ossicles

  • aka EARDRUM

ossicles

bones of middle ear that carry sound vibrations

ossicles are composed of

malleus, incus, and stapes that connect to oval window, which transmits the sound of vibrations to the cochlea of the inner ear

eustachian tube

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

inner ear

bony spaces within the temporal bone of the skull made up of 3 distinct parts: cochlea, semicircular canals, and vestibule

cochlea

facilitates hearing

• coiled portion of inner ear containing sensory organ for hearing

• connects to oval window in middle ear

semicircular canals and vestibule

• sensory organ of balance

• contains receptors and endolymph that provide sensory info about the body’s position to maintain equilibrium

vestibulocochlear nerve

• cranial nerve responsible for hearing and balance

• composed of vestibular and cochlear fibers

• aka acoustic or auditory nerve

vestibular nerve

cranial nerve branch that conveys info about position and balance from the semicircular canals and vestibule to the brain