1. ANATOMY UNIT 2 NOTES: Hearing & Equilibrium

2. (1) Ear Design Ear is a well designed funnel: Sound Path:
Sound waves spiral down into auditory canal.
Sound Waves smack against ear drum (tympanic membrane).
Sound Path:
Inside ear
Tympanic Membrane (Ear Drum)
Hammer, Anvil, Stirrup (3 Bones)
Oval Window of Cochlea
Fluid within Cochlea
Cochlear Nerve and Brain

5. (2) Cochlea Cochlea = Snail like structure in inner Ear.
Contains receptors for balance and equilibrium.
Contains receptors for pitch and frequency.

8. (3) Equilibrium & Balance
Your ears keep track of your body’s position.
Equilibrium receptors lie within the cochlea (they are called the Vestibular Apparati).
2 Types of Equilibrium:
Static
Dynamic

9. (4) Static Equilibrium
Static = Tells brain the basic position of head.
Up, Down, Left, Right, Forward, Back
Uses Receptors called the Macuale:
On top of maculae lies the otolithic membrane (gel-like membrane)
When Head Moves  Otoliths Move!
Movement of otoliths places pressure on maculae, sending message through vestibular nerve to brain.

11. (5) Dynamic Equilibrium
Dynamic = Tells brain the more detailed positioning and movement of the head.
Rotations and Angles
Uses the Semicircular Canals of Cochlea:
Contain channels called Crista Ampullari.
Crista Ampullari contain receptor cells, endolymph fluid and a capula cap.
When head turns, fluid pushes against capula cap, stimulating receptors, and sending message to brain.

13. (6) Motion Sickness The result of an inefficient dynamic equilibrium…
Semicircular Canals either too sensitive or too slow at sending messages
Too many visual messages
Too many inner ear messages
Visual conflicts with Inner Ear
Unique to each individual

14. (7) Deafness
Deaf = Any hearing loss
Types:
Conduction
Sensorineural

15. (8) Conduction Deafness
Something Blocks Tympanic Membrane
Sound Waves cannot reach Ear Drum + Inner Ear
Causes:
Ear Wax
Ruptured Ear Drum
Injured Hammer, Anvil and/or Stirrup
Usually Temporary, Solved by Surgery

16. (9) Sensorineural Deafness
Damage to actual parts of ears:
Receptor Cells
Cochlea
Vestibular Nerve
Can be hereditary, damage from disease/virus, damage from loud noises
Often permanent