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Ear

Components covered in this ear section:

  • Outer Ear

  • Middle Ear

  • Inner Ear

Outer Ear

 

Outer ear:

  • Helix

  • Antihelix

  • Tragus

  • Antitragus

  • External acoustic meatus

  • Lobule

Middle Ear

 

Middle ear:

  • Tympanic membrane

  • Ear ossicles

  • Muscles

  • Communications

  • Chorda tympani nerve

 

 

Tympanic Membrane

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • Tympanic membrane- in contact with external ear

 

Ear Ossicles

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ear ossicles:

  • Hammer/Malleus- in contact with tympanic membrane

  • Anvil/Incus

  • Stirrup/Stapes- in contact with oval window

 

 

Muscles

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Muscles related to the ear ossicles:

  • Tensor tympani- pulls malleus medially tensing tympanic membrane (decreasing amplitude of oscillations)

    • Innervated by CN V3 (mandibular nerve)

  • Stapedius- pulls stapes posteriorly (decreasing oscillation range)

    • Innervated by CN VII (facial nerve)

 

 

Communications

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Communications:

  • Pharyngotympanic/eustachian tube- connected anteromedially to nasopharynx

  • Mastoid air cells- connected posterosuperiorly to mastoid antrum

 

 

Chorda tympani nerve

 

Chorda tympani nerve:

  • Branches off CN VII (facial nerve) in middle ear

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Inner Ear

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Inner ear contains:

  • Bony labyrinth- series of bone lined chambers containing perilymph fluid

  • Membranous labyrinth- membranous chambers inside bony labyrinth containing endolymph fluid

  • CN VIII (vestibulocochlear nerve)

 

 

Bony Labyrinth

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bony labyrinth:

  • Vestibule

  • 3 Semicircular canals

    • Anterior semicircular canal

    • Lateral semicircular canal

    • Posterior semicircular canal

      • Ampulla- dilatation at the end of SCCs

  • Cochlea

 

 

Membranous Labyrinth

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Membranous labyrinth:

  • 2 sacs

    • Utricle

    • Saccule

  • 3 semicircular ducts

    • Anterior semicircular duct

    • Lateral semicircular duct

    • Posterior semicircular duct

  • Cochlear duct

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