Auditory sense

1. Auditory Sense (Hearing) pg 6

2. Structure of the Ear Outer Ear

3. Structure of the Ear Outer Ear Auricle ( pinna ): fleshy, visible part of the ear. Made of elastic cartilage. Helps collect sound waves

4. Structure of the Ear Outer Ear Auricle ( pinna ): fleshy, visible part of the ear. Made of elastic cartilage. Helps collect sound waves External auditory canal ( meatus ): Tube about 2.5 cm long. Contains hairs and glands that produce cerumen

5. Middle Ear

6. Middle Ear Tympanic membrane (eardrum): Separates outer ear from middle ear. Sound waves cause it to vibrate

7. Middle Ear Tympanic membrane (eardrum): Separates outer ear from middle ear. Sound waves cause it to vibrate Auditory ossicles : 3 tiny bones– malleus (hammer), incus (anvil), and stapes (stirrup). Transmit vibrations from the eardrum to the inner ear. Malleus is attached to the eardrum. Stapes is attached to the oval window

8. Middle Ear Tympanic membrane Auditory ossicles Eustachian tube: Connects the middle ear with the upper part of the throat. Allows air pressure to equalize on both sides of the eardrum

9. Inner Ear

10. Inner Ear Vestibule and Semicircular canals: function in the sense of equilibrium

11. Inner Ear Vestibule and Semicircular canals: function in the sense of equilibrium Cochlea: functions in hearing. Resembles a snail’s shell. Contains the organ of Corti , which sits on the basilar membrane and contains numerous hair cells that are linked to neurons

12. Physiology of Hearing

13. Physiology of Hearing Sound waves cause the tympanic membrane to vibrate

14. Physiology of Hearing Sound waves cause the tympanic membrane to vibrate Malleus , incus , and stapes transfer vibrations to the oval window

15. Physiology of Hearing Sound waves cause the tympanic membrane to vibrate Malleus , incus , and stapes transfer vibrations to the oval window Movement of the oval window causes waves to form in the fluid within the cochlea

16. Physiology of Hearing Sound waves cause the tympanic membrane to vibrate Malleus , incus , and stapes transfer vibrations to the oval window Movement of the oval window causes waves to form in the fluid within the cochlea The waves cause the basilar membrane to vibrate, which bends the hair cells on the organ of Corti

17. Physiology of Hearing Sound waves cause the tympanic membrane to vibrate Malleus , incus , and stapes transfer vibrations to the oval window Movement of the oval window causes waves to form in the fluid within the cochlea The waves cause the basilar membrane to vibrate, which bends the hair cells on the organ of Corti Bending stimulates nerve impulses, which are transmitted to the brain

18. Pitch and Loudness Pitch: Each region of the basilar membrane is “tuned” to a particular pitch. High pitched sounds cause vibrations at the base of the membrane while low pitched sounds cause vibrations at the apex

19. Pitch and Loudness Pitch: Each region of the basilar membrane is “tuned” to a particular pitch. High pitched sounds cause vibrations at the base of the membrane while low pitched sounds cause vibrations at the apex Loudness: Loud sounds cause larger vibrations in the basilar membrane, which leads to more nerve impulses reaching the brain