exercise 25 special senses: hearing and equilibrium

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auricle or pinna

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external auditory canal

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tympanic membrane

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Malleus (hammer)

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Incus (anvil)

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Stapes (stirrup)

Auditory ossicles transfer method

1. Lever system made from tiniest bones in the body

2. Transfers vibrations produced at the ear drum and conveys them to the inner ear at the oval window

3. Transfers vibrations to liquid perilymph

identify this structure

pharyngotympanic (eustachian) tube

• connects middle ear with the nasopharynx / equalizes middle ear pressure

what is otitis media

• Mucus membranes of the nasopharynx is continuous with the middle ear

• Pharyngeal infections can travel up the Eustachian tube and causes inflammation in the middle ear

• Common in young children because their Eustachian tubes are relatively

what is round window

pressure relief from inner ear

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Helix

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Lobule

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external acoustic meatus

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external ear

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middle ear

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internal ear (labyrinth)

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auditory ossicles

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vestibular apparatus (balance & equilibrium)

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cochlea (hearing)

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Vestibulocochlear nerve (VIII)

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vestibular branch (VIII)

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Cochlear branch (VIII)

what is perilymph

aqueous fluid that fills the bony labyrinth

what is endolymph

viscous fluid that fills the ducts of the membranous labyrinth

• created in the cochlear duct and drains into the endolymphatic sac

what is this structure

perilymph

what is this structure

endolymphatic duct

what is this structure

endolymphatic sac

identify this structure and what does it contain

vestibule

• contains the sac-like utricle & saccule / involved in static equilibrium (up/down, gravity, G-forces)

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Utricle

• horizontal movements

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Saccule

• vertical movements

  • movements of the head when the body is static, posture, gravity

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semicircular canals

• contains the semicircular ducts and involved in dynamic equilibrium (positional and rotation)

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semicircular duct

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cochlea

• which is responsible for hearing

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cochlear duct (scala media)

• contains the organ of corti and is filled with endolymph

scala vestibuli and scala tympani is filled with what

they are both filled with perilymph

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ampulla

• Contain crista ampullaris

  • hair cells covered with a gelatinous cap called a cupula

Moniters dynamic equilibrium

what is the definition of a hair cell and hat are they associated with

Hair cell: the sensory receptors in the semicircular ducts, vestibule (utricle & saccule) & cochlear duct

• they are associated with sensory neurons

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hair cell

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sensory neuron

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bony labyrinth

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ampulla

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crista ampullaris

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hair cells

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cochlear duct

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scala vestibuli

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scala tympani

identify this cell membrane structure

vestibular membrane

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tectorial membrane

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basilar membrane

identify this testing method

weber test

• Sound is heard equally in both ears

  • Equal hearing in both ears (normal hearing)

  • Equal loss of hearing in both ears

• sound is heard unequally

  • Defective ear does not hear as well as normal ear: Sensorineural hearing loss or deafness

  • Defective ear hears better than normal ear: Conduction hearing loss or deafness

identify this testing method

Rinne test

• Air conduction > Bone conduction

  • Hearing not impaired (+)

• Bone Conduction > Air conduction

  • Some degree of conduction hearing loss or deafness (-)

what is nystagmus

is involuntary eye movements produced in response to rotating movements

what is Vertigo

is a sensation of dizziness and often accompanies nystagamus

weber test determines sensorineural deafness (presbycusis), but what is the definition of presbycusis

caused by damage of the neural structures

what kind of test is this

rinne test bone conduction

what kind of test is this

rinne test air conduction

weber test determines Conduction deafness, but what is the definition of Conduction deafness

caused by anything that stops the sound conduction to the inner ear