1. The Ear

2. Anatomy of the Ear External Ear Auricle or pinnae surrounds the ear
Helix
Lobule

3. Anatomy of the Ear External acoustic meatus
Ceruminous glands produce wax
Hair
Sebaceous glands
Tympanic membrane
Separates the outer ear from the middle ear
Vibrates at the same frequency as the sound wave

4. Ear
Figure 17.20

5. Middle ear- tympanic cavity
Auditory ossicles – lever system that transmits the sound wave to the inner ear
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
Oval window – transmits the coming sound to the inner ear

6. Middle ear- tympanic cavity
Round window – secondary tympanic membrane
Auditory, Eustachian or Pharyngotympanic Tube – connects the middle ear with the nasopharynx
Otites media – inflammation of the middle ear.
Myringotomy – lancing of the eardrum

7. Inner Ear

8. Inner ear
Bony or osseous labyrinth surrounds and protects membranous labyrinth
Perilymph – aqueous fluid that fills the bony labyrinth
Vestibule – involved in static equilibrium
Semicircular canals – involved in dinamic equilibrium
Lateral, anterior, posterior
Cochlea – responsible for hearing

9. Inner ear Membranous Labyrinth
Endolymph – viscous fluid that fills the ducts
Cochlear ducts – located in the scala media
Semicircular ducts – located in the semicircular canals
Vestibule – located inside of the vestibule canal

10. Inner Ear

11. Microscopic anatomy of Organ of Corti
Organ of Corti – for hearing
Basilar membrane – forms the floor of the cochlear duct and supports the Organ of Corti
Tectorial membrane – overlies the Organ of Corti. It’s gel-like and is in contact with the stereocilia of the hair cell
Vestibular membrane – separates the scala vestibular from the scala media

12. Microscopic anatomy of Organ of Corti
Scala vestibuli – filled with perilymph
Scala tympani – filled with perilymph
Scala media – filled with endolymph

13. Tests of Hearing Sound localization Frequency range
Frequency is perceived a pitch. The higher the frequency the higher the pitch

14. Tests of Hearing Weber’s Test – determines:
Sensorial deafness (Presbicusis)- caused by damage of the neural structures
Conduction deafness- cased by anything that stops the sound conduction to the inner ear
Rinne test
Compares bone and air conduction hearing

15. Tests of Hearing Audiometry Measures frequency in hertz
Measures amplitude in decibels. Amplitude is perceived as intensity or loudness of the sound

16. Microscopic anatomy of Equilibrium Apparatus
Vestibular Apparatus
Divided into utricle and saccule
Macula
Hair cells
Otolithic membrane

17. Inner Ear
Figure 17.23a, b, & d

18. Vestibular apparatus Monitors static equilibrium Ups and downs
Movement of the head when the body is static
Ups and downs
Straight line changes
Posture

19. Microscopic anatomy of Equilibrium Apparatus
Semicircular canals and ducts
Anterior, posterior and lateral
Ampulla
Hair cells
Cupula

20. Inner Ear
Figure 17.23a, b, & d

21. Semicircular canals and ducts
Monitor dynamic equilibrium
Perception of the rotational orientation of the head when the body is moving
Boat riding

22. Tests on equilibrium Balance test
Walk in straight line placing one foot directly in front of the other
Barany test
Evaluates the semicircular canals
Rotates the person sitting in a rotating chair. Stop the rotation and observe if the person has nystagmus and vertigo
Nystagmus is normal after rotation only
Vertigo – dizziness and rotational movement when the person is static

23. Tests on equilibrium Romberg’s test
Determines the integrity of the dorsal white column of the spinal cord
Observes swaying movements when the person is standing erect and staring straight ahead
Role of vision on equilibrium