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THE EAR NOTES:
The ear is divided into 3 parts: outer, inner and middle.
The outer (external) ear:
-Composed of the pinna and the external auditory canal. The pinna is also known as the auricle. -This
structure is what most people refer to as the “ear”.
1.
The external auditory canal is a short narrow chamber about 1 inch long, carved into the temporal
bone of the skull.
2. Inside the auditory canal are ceruminous glands, which secrete a waxy yellow substance, called
earwax, or cerumen.
3. Sound waves eventually hit the tympanic membrane or eardrum, and cause it to vibrate.
The middle ear:
1.) The middle ear is also referred to as the tympanic cavity. It is a small, air filled cavity.
2.) Three of the smallest bones in the body are located here, and they are called the ossicles.
3.) These bones are named for their shape: hammer (malleus), anvil (incus) and the stirrup (stapes).
The inner ear:
1.) The inner ear is a maze of bony chambers called the osseous or bony labyrinth.
2.) It is located just behind the eye socket.
3.) There are 3 divisions of the inner ear called the: cochlea, vestibule, semicircular canals.
4.) The inner ear is filled with fluid.
How do we hear?
Within the cochlea is the organ of Corti, which contains hearing receptors, called hair cells. Sound waves reach
the cochlea through vibrations of the eardrum, ossicles, and oval window set fluids in motion. Once stimulated, hair
cells transmit impulses along the cochlear nerve, to the auditory cortex in the brain.
Here is the path:
PinnaAuditory canalEardrum (tympanic membrane)Hammer, anvil, stirrupoval windowfluids in cochlear
canals
Equilibrium: Semicurlar Canals of inner ear
There are two types of equilibrium: static & dynamic
1) Static: Body is not moving, at rest
2) Dynamic: Body is in motion
Diseases/Conditions/Disorders:
1) Deafness: hearing loss of any degree
2) Vertigo: sensation of spinning
3) Otitis media: ear infection