The Ear

The Ear

1. Outer ear

   • Pinna - visible part of the ear, funnels sound intot he ear canal, made of cartilage
   • Ear canal - leads to the ear drum
   • Ear drum - membrane of skin, vibrates when sound hits it

2. Middle ear

   • Ossicles (Hammer - mallus, Anvil - incus, Stirrup - stapes
   • Eustachian tube - keeps pressure equal on both sides of ear drum

3. Inner ear

   • Cochlea - fluid filled, coiled, helps with hearing
   • Semi-circular canals - helps with balance

4. We hear by...

   • The pinna channeling the sound to the eardrum
     • The eardrum vibrates, which then causes the ossicles to vibrate, which amplify the sound by 20 times
       • The stirrup pushes on the oval window against the cochlea, which moves the lymph inside
         • Special hairs, which are nerve endings, sense the movement and send messages to the brain along the auditory nerve
           • The brain interprets these messages as sound
             • We hear.

5. We have 3 semi-circular canals so we can have balance in 3 planes

6. Deafness can be caused by long exposure to high levels of noise, explosions, born with a problem with the cochlea, drugs or ear infections