Ears Anatomy and Physiology

external ear

acts as a funnel, collecting and channeling sound waves from a large peripheral field into the ear canal

auricle

also called the pinna. external appendages on each side of the head. captures and funnels sound waves toward the ear's interior and helps to amplify the intensity of sound waves up to seven times.

auditory ossicles

attached to the tympanic membrane and consists of three small bones called the malleus, incus, and stapes. function is to conduct mechanical vibration from the tympanic membrane to the inner ear.

middle ear

begins inside the tympanic membrane and includes the tiny bones of the ear called auditory ossicles and the eustachian tube

acoustic nerve

connects the inside of the inner ear to the brain, and is a combination of the otic nerve that projects from the cochlea and the vestibular nerve that projects from the semi-circular canals

endolymph

controls balance, senses body position, and is responsible for body position equilibrium

inner ear

converts sound waves into electrical signals for transmission to the brain and controls balance

structures of the external ear

includes the auricle, external ear canal, ceruminous glands, and the tympanic membrane

structures of the inner ear

includes the vestibule, semicircular canals, cochlea, organ of corti, and the acoustic nerve

tympanic membrane

located at the end of the inner portion of the external auditory canal and is an elastic membrane that stretches over the internal end of the canal. resembles a white pearl in appearance if healthy. function is to convert sound waves to mechanical vibrations. separates the external and middle ear. also known as the eardrum.

vestibule

located in the central section of the inner ear and is a small chamber where sound vibrations enter the internal ear. responsible for collecting sound vibrations from the middle ear and carrying them to the inner ear.

cochlea

located in the lower section of the inner ear and is a spiral-shaped, hollow cone filled with ionic fluids, endolymph, and a thinner fluid called perilymph. the fluid picks up vibrations from the stapes and transforms the sound waves into electrical signals for transmission to the brain. contains the organ or corti.

semicircular canals

located in the upper section of the inner ear and consists of three half-circular canals arranged at right angles to each other. each canal contains a fluid called endolymph.

eustachian tube

opens in the inner part of middle ear and leads downward to the pharynx and is responsible for equalizing air pressure on both sides of the tympanic membrane

cerumen

provides protection to the external auditory canal and helps keep it moist. also known as earwax.

ceruminous glands

specialized glands that produce a substance called cerumen

organ or corti

structure that converts sound waves into nerve impulses via mechanically sensitive hair cells. referred to as the sensory organ of hearing.

external auditory canal

tube located between the auricle and tympanic membrane. acts like a resonance chamber, helping to amplify the waves of specific frequencies. the outer third of the canal contains many short hairs and ceruminous glands.