A&P: outer ear

sound

- disturbance of air that moves in a wavelike fashion through the air

- sound is the flow of power or a transfer of energy from one place to another

our ears can

- accept a wide range of sound pressure

- hear 20-20,000 Hz

- differentiate small increments in frequency and intensity

- listen to a signal embedded in background noise

- process extremely rapid sequences of sounds

audition (SoH)

the process associated with hearing which is an essential element of verbal communication

energy transducer

converts acoustic energy into electrochemical energy

three basic components of the outer ear

- pinna/auricle

- external auditory meatus

- tympanic membrane

pinna/auricle

- serves as a collector of sound to be processed at deeper levels

- primarily made of cartilaginous framework

- has ridges, grooves, and dished-out regions

external auditory meatus

- EAM

- ear canal

- approx 7mm in diameter and 2.5 cm long

tympanic membrane

- most medial portion of the EAM

outer 1/3 of EAM

- lined with hairs and has cerumen

- traps insects and dirt which protects the medial most point of the outer ear, the tympanic membrane

osseous meatus of EAM

- medial 2/3 of the canal

- surrounded by the temporal bone

isthmus

- junction of the cartilaginous and bony framework of the ear canal

tympanic membrane

- thin 3 layer sheet tissue: epithelial cover, middle layer, inner layer

- TM is slightly concave oval structure - the umbo the most depressed portion of this convacity

fibrocartilaginous ring (TM)

fits into the tympanic sulcus, a groove in the temporal bone

epithelial cover of the pinna

- continues into EAM

- is the outer layer of the TM

middle layer of TM

- fibrous tissue

- provides structure

inner layer of TM

- mucosa lining of the middle ear

the outer ear is

- a collector of sounds

- directing sound waves

- an excellent funnel for sound

- localizing the source of sounds