1. Anatomy of the Ear
Chapter 8

2. Functions
Hearing
Equilibrium and Balance

3. External Ear Pinna (auricle) External Auditory Canal
Collects & directs sound waves into the auditory canal
External Auditory Canal
Short, narrow chamber that directs sound waves to the tympanic membrane
Tympanic membrane (eardrum)
Sound waves vibrate the membrane

4. Middle Ear (tympanic cavity)
Air filled cavity
Auditory (Eustachian) tube
Connects middle ear to throat
helps equalize pressure in ear
Did you know…
In infants, the auditory tube is more horizontal, therefore, when children get sore throats they usually are more prone to ear infections.

5. Spanned by ossicles which transmit the vibratory motion of the eardrum to the oval window and the fluids of the inner ear
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)

6. Inner Ear Osseous- bony chambers filled with fluid Cochlea Vestibule
Contains organ of Corti which contains hair cells (hearing receptors) that transmits the impulses to the vestibulocochlear nerve and finally the temporal lobe of the brain
Vestibule
Semicircular canals

7. Hearing Sequence of Events
Pinna
External auditory tube
Tympanic membrane
Malleus
Incus
Stapes
Oval window
Organ of Corti in Cochlea
Hairs cells
vestibulocochlear nerve

8. Equilibrium Static (at rest)
Maculae (receptors) in vestibule report the position of the head to the pull of gravity when the body is not moving
Maculae transmit message to vestibular nerve that tells cerebellum your head’s position in space (balance)

9. Dynamic
Dynamic equilibrium receptors in semicircular canal respond to angular or rotatory movements of the head and transmit message to cerebellum via the vestibular nerve

10. Deafness Hearing loss of any degree 2 kinds: Conduction deafness
Something interferes with the conduction of sound vibrations to the fluids of the inner ear
Caused by:
Mechanical factors such as build up of earwax, fusion of ossicles, ruptured ear drum

11. Sensorineural deafness
Degeneration or damage to the receptor cells in the organ of Corti, the cochlear nerve or to neurons in the auditory cortex of the brain
Due to problem of nervous system structures
Did you know….
Hearing Aids only improve the hearing of patients with conduction deafness.