1. Hearing and Equilibrium

2. Outer Ear
Auricle– “ear” shell- shaped, surrounds external opening to auditory canal
Auditory canal – channel through temporal bone
Tympanic membrane- eardrum; vibrates when stimulated by sound waves.

3. Middle Ear
Air filled cavity called tympanic cavity (middle ear cavity)
From eardrum to bony wall with oval and round window
Auditory tube runs down connecting ear to throat

4. Functional parts of middle ear
Ossicles- 3 small bones
Hammer (malleus), Anvil (incus), and Stirrup (stapes)
Eardrum vibrates hammer, which moves anvil, which then moves stirrup, opening oval window.
Oval window moves fluids inside inner ear

5. Inner Ear Located deep inside temporal bone (behind eye socket)
Contains 3 major divisions

6. Anatomy of Inner ear
Cochlea- contains auditory (cochlear) nerve, which transmits sound impulses; hair cells receive vibrations from oval window, indicating sound
Different pitches affect different areas of cochlea

7. Semicircular canal Located in inner ear
Responsible for maintaining balance/equilibrium
Otoliths float inside canal
Hair cells recognize when the otolith moves, alerting the body of its positioning when static

8. Dynamic equilibrium
Position while moving is determined in semicircular canal
Triggered when spinning, moving on a boat, etc.
Causes dizziness and motion sickness

9. Types of Deafness
Conduction – problem in conduction of sound vibrations; hearing aids can help by transmitting sound to/through bone
Sensorineural – degeneration or damage to nerves which carry impulse.