Sensory Information

1
Sensory Information

• Hearing and Equilibrium

2
Major Functions

• Hearing
• Equilibrium
• In the inner ear there are tiny hair cells (which
  are ciliated)
• Movement of these cilia generate an action
  potential
• Remember We are still dealing with neurons or
  nerve cells.

3
Structure and Function

• Ear is divided into three sections
• Outer ear
• Middle ear
• Inner ear

4
The Outer Ear

• Pinna External Flap, Collects Sound
• Auditory canal carries sound to the ear drum

5
Middle Ear

• Begins with the
• Tympanic membrane this is also known as the
  eardrum.
• Attached to the ear drum
• Ossicles tiny bones that amplify and carry the
  sound in the middle ear.
• 3 different bones Malleus (hammer), Incus
  (anvile) and Stapes (Stirrup)

6
Middle Ear Continued

• Ossicles In particular the stapes, will strike
  the oval window.
• Oval window Hole in the vestibule, covered by a
  thin layer of tissue (ex. like a drum)
• Sound is amplified when it gets transferred from
  the large tympanic membrane to the smaller oval
  window.

7
Lastly

• Eustachian tube air-filled tube of the middle
  ear that equalizes pressure between the external
  and internal ear.
• Causes your ear to popMost noticable during
  travels on airplanes, increases altitude causes
  pressure changes, pressure is equalized by the
  Eustachian tube.

8
Inner Ear

• Connected to the middle ear is
• Vestibule Provides information about
  equilibrium.
• Contains hair cells similar to the ones in the
  organ or corti
• These nerves act upon the vestibular nerve, which
  signals the position of the head relative to the
  body.

9
Inner Ear Contd

• Semicircular canals fluid-filled structures
  that also provide information about equilibrium
• Most important part of the ear
• Cochlea Coiled structure that responds to
  various sound waves and converts them to nerve
  impulses.

10
Overview
11
Inner Ear Overview
12
So How Is Sound Heard ?

• Sound is a form of energy and must be converted
  into an electrical impulse (to generate AP)
  before we interpret it.
• Important to know that sound travels through both
  air and water.
• In fact, it travels through water 4x faster than
  the air.

13
Hearing Sound

• Hearing Begins
• Sound waves push against tympanic membrane (ear
  drum)
• Vibrations passed along by the 3 ossicles (which
  concentrate an amplify the vibrations, up to
  triple the force)
• And move the membrane in the oval window.
• Mechanism for protection (smallest muscle in your
  body controls movement of malleus reducing the
  intensity

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Hearing Sound Contd

• Once at the oval window
• Oval window is pushed inward, triggers fluid in
  the Cochlea to move causing waves.
• These waves are converted to into electrical
  impulses (interpret as sound)
• Hearing apparatus within the cochlea is the organ
  of Corti (primary sound receptor)

15
Organ of Corti

• Contains specialized hair cells anchored to the
  basilar membrane
• There hair cells respond to the vibrations of the
  basilar membrane in the cochlea.
• Movement stimulates sensory nerves and travels
  via the auditory nerves to the temporal lobe of
  the brain to be processed as sound.

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Cochlea and Membranes
17
Organ of Corti
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Video !

• Hearing Sound - Putting it all together

Cochlea Stretched Out
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ENDDDDD !!!!!

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