Post on 14-Jul-2015
ANATOMY
UNIT 2 NOTES:
Hearing & Equil ibrium
(1) Ear Design
• Ear is a well designed funnel:– 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
(2) Cochlea
• Cochlea = Snail like structure in inner Ear.
• Contains receptors for balance and equilibrium.
• Contains receptors for pitch and frequency.
(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
(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.
(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.
http://www.youtube.com/watch?v=vTiGskc1o48
(8) 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
(7) Deafness
• Deaf = Any hearing loss
• Types:– Conduction– Sensorineural
(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
(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