Anatomy and Physiology of the Ear Flashcards
Three Divisions of the Ear
- Outer–> outside to ear drum
- Middle–> ear drum to cochlea
- Inner–> cochlea to end of canal
Outer ear functions
Non-acoustic: - Cleaning - Protection Acoustic functions: - Locates sound - Collects sound - Funnels sound
Audition
the process of hearing
The ear’s functions
- Transducer–> changes energy into a different form
- Maintainer of equilibrium (balance)
Main parts of outer ear:
- Pinna (auricle)
- External Auditory Meatus (EAM)
EAM
- Shaped: s-shaped
- 7mm in diameter
- 2.5 cm long
- 1/3 cartilage, 2/3 bone
Cerumen
- ear wax
- Keeps canal moist
- Inhibits the formation of bacteria
- Prevents insects from entering
- Cleans the canal
Outer ear problems
- Otitis external: inflammation of the ear
- Cerumen impaction
- Microtia
- Pinna position: low-set ears
Microtia
Grade 1: smaller than normal, but the ar has mostly normal anatomy
Grade 2: Par of the ear looks normal (usually lower half), the canal may be normal, small, or completely closed
Grade 3: “peanut-shaped”; no canal
Grade 4: Complete absence of both the external ear and the ear canal also called “anotia”
Middle Ear Parts
- Tympanic Membrane
- Malleus
- Incus
- Stapes
- Eustachian tube
Tympanic membrane
- Shape: oval
- Diameter: 10 mm
- Angle: 55 degrees
- Three layers: outer, intermediate, inner
Ossicles
1) Malleus or Hammer
2) Incus or Anvil
3) Stapes or stirrup
Muscles of the middle ear
- Stapedius muscle
- Tensor Tympani muscle
Eustachian tube
1) Connects middle ear with pharynx
2) 36mm long
3) Usually collapsed, but opens during yawning, chewing, and swallowing
4) Aerates middle ear
5) Equalizes pressure
Middle Ear Problems
- Otitis media: middle ear infection
- Otosclerosis: ear scarring
