The Ear 1 Anatomy of the Ear l

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The Ear 1

The Ear 1

Anatomy of the Ear l External Ear ¡Auricle or pinnae surrounds the ear l.

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

Anatomy of the Ear ¡External acoustic meatus l. Ceruminous glands produce wax l. Hair

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

Ear 4 Figure 17. 20

Ear 4 Figure 17. 20

Middle ear- tympanic cavity l Auditory ossicles – lever system that transmits the sound

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

Middle ear- tympanic cavity l Round window – secondary tympanic membrane l Auditory, Eustachian

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

Inner Ear 7

Inner Ear 7

Inner ear l Bony or osseous labyrinth surrounds and protects membranous labyrinth ¡Perilymph –

Inner ear l 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 l. Lateral, anterior, posterior ¡Cochlea – responsible for hearing 8

Inner ear l Membranous Labyrinth ¡Endolymph – viscous fluid that fills the ducts ¡Cochlear

Inner ear l 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 9

Inner Ear 10

Inner Ear 10

Microscopic anatomy of Organ of Corti l Organ of Corti – for hearing ¡Basilar

Microscopic anatomy of Organ of Corti l 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 11

Microscopic anatomy of Organ of Corti ¡Scala vestibuli – filled with perilymph ¡Scala tympani

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

Tests of Hearing l Sound localization l Frequency range ¡Frequency is perceived a pitch.

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

Tests of Hearing l Weber’s Test – determines: ¡Sensorial deafness (Presbicusis)caused by damage of

Tests of Hearing l 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 l Rinne test ¡Compares bone and air conduction hearing 14

Tests of Hearing l Audiometry ¡Measures frequency in hertz ¡Measures amplitude in decibels. Amplitude

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

Microscopic anatomy of Equilibrium Apparatus l Vestibular Apparatus ¡Divided into utricle and saccule ¡Macula

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

Inner Ear 17 Figure 17. 23 a, b, & d

Inner Ear 17 Figure 17. 23 a, b, & d

Vestibular apparatus l Monitors static equilibrium ¡ Movement of the head when the body

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

Microscopic anatomy of Equilibrium Apparatus l Semicircular canals and ducts ¡Anterior, posterior and lateral

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

Inner Ear 20 Figure 17. 23 a, b, & d

Inner Ear 20 Figure 17. 23 a, b, & d

Semicircular canals and ducts l Monitor dynamic equilibrium ¡Perception of the rotational orientation of

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

Tests on equilibrium l Balance test ¡Walk in straight line placing one foot directly

Tests on equilibrium l Balance test ¡Walk in straight line placing one foot directly in front of the other l 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 22

Tests on equilibrium l Romberg’s test ¡Determines the integrity of the dorsal white column

Tests on equilibrium l 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 l Role of vision on equilibrium 23