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Flashcards in The Ear Deck (34):
1

Transmission of Sound

  • Sound enters external acoustic meatus
  • Vibrates tympanic membrane
  • moves Malleus, then Incus, then Stapes
  • vibrates oval window
  • transmits waves in scala vestibuli and scala tympani
  • vibrates membrane of cochlear duct
  • spinal nerve VIII (Vestibulocochlear nerve)

2

Contents of external ear

  • Auricle - collects sound
  • External Acoustic Meatus 

3

Contents of Middle Ear

  • Auditory ossicles
  • Stapedius
  • Chorda Tympani
  • Tensor tympani
  • Tympanic nerve plexus 

4

Contents of Inner Ear 

  • Vestibulocochlear organ - hearing and balance 

5

What do all chromosomal abnormalities have in common

Ear developmental anomalies 

6

Muscles, Nerves (+ spinal levels), and Vascularization of Auricle 

  • Auricular musles (facial expression muscles)
  • Blood supply via terminal branch of External Carotid Artery
  • Innervation - Genereal Sensory fibers of
    • Greater auricular nerve (C2)
    • Lesser occipital nerve (C2-C3)
    • Auricotemporal nerve (V3)
    • VII (Facial)
    • IX (Glossopharyngeal)
    • X (Vagus)

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7

Innervation of External Acoustic Meatus

  • Auricotemporal Nerve (Branch of Mandibular V3)
  • VII
  • IX
  • X

8

Future ear bones (embryology)

Mesnchymal condensation 

9

Germ layers of middle ear

  • Ectoderm - Tympanic membrane
  • Mesoderm - Eardrum
  • Ectoderm - External Ear

10

How does the middle ear communicate with the mastoid area?

Pharyngotympanic tube

11

Innervation of Middle Ear Structures

Tympanic Plexus 

  • Branch of IX (Glossopharyngeal nerve) - Visceral Sensory fibers

12

Bone separating middle ear cavity from mid cranial fossa

Tegmen tympani

13

Vessel running directly under floor of middle ear

Internal Jugular Vein 

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14

Function of Pharyngotympanic tube; what is it opened by?

  • Equilize pressureon both sides of tympanic membrane
  • opened by tensor veli palatini and levator veli palatini

15

Tensor Tympani 

  • Innervation : V3 branchiomotor
  • Function: Pulls tympanic membrane to reduce vibrations after loud noises
     

16

Stapedius 

  • Innervation: VII - branchiomotor 
  • Function: Pulls stapes posteriorly to prevent excessive oscillation after loud noise 

17

Tympanic Plexus 

  • Made from Branch of IX Branchiomotor (Visc sensory & Visc. parasympathetic)  and Internal Carotid Plexus (sympathetic)
  • gives rise to Lesser Petrosal Nerve
    • exits jugular foramen
    • enters otic ganglion
    • parasympathetic innervation to Parotid Gland

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18

Facial artery travels with what through what opening in cranium

  • Travels with Vestibulocochlear nerve (VIII) through Internal acoustic meatus
  •  

19

Ganglionic body for facial nerve in Temporal Bone

Geniculate ganglion

  • Cell bodies for
    • General sensory fibers (Ear)
    • special sensory fibers (taste)
    • Visceral sensory fibers (palate)

20

Branches of Facial nerve in Temporal Bone

  1. Greater petrosal nerve
  2. Nerve to stapedius
  3. Chorda tympani

21

Contents of Bony Labyrinth 

  • Vestibule
  • 3 Semicircular canals
  • Cochlea

Contains perilymph, similar to CSF

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22

Membranous Labyrinth

  • Cochlear duct - Hearing
  • 3 semicircular ducts - balance
  • Utricle - balance
  • Saccule - balance 

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23

Vestibule (part of bony labyrinth)

  • Recieves vibrations from oval window
  • Communicates with Cochlea and Semicircular canals
  • vestibular aqueduct passes to cranial cavity
    • stores excess endolymph made in membranous labyrinth)

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24

Semicircular Canals (part of bony labyrinth)

Connected to Vestibule 

Covers Semicrircular Ducts 

25

Semicircular Canals 

  • Part of membranous labyrinth 
  • important in BALANCE 
  • drain into utricle
  • convey information about rotational motion
     

26

Utricle

  • BALANCE 
  • responds to linear accerleation 
  • gets endolymph from semicircular ducts 
     

27

Endolymphatic Duct 

  • Drains from utricle/saccule into vestibular aqueduct
  • Ultimately to endolymphatic sac
     

28

Cochlea (internal ear)

  • part of bony labyrinth 
  • twists self around bony core - Modiolus
  • Cochlear duct separates scala tympani and scala vestibuli
    • continuous w/ eachother at helicotrema
  • Cochlear aqueduct connects perilymph to subarachnoid space

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29

Contents of cochlear duct vs contents of scala vestibuli/scala tympani

  • Cochlear duct - filled with endolymph
  • Scala tympani/scala vestibuli - filled with perilymph 

 

30

Organ of hearing

  • Spiral organ of corti
  • inside Cochelar duct

31

Vestibulocochlear Nerve (VIII)

  • Origin: Pons
  • Course: through internal acoustic meatus (IAM)
  • Components: special sensory 
  • Ganglion: cochlear (spiral) and vestibular ganglia (sensory cell bodies here)
  • Distribution: Cochlea, semicircular canals, utricle, saccule
  • Function: Hearing & equilibium 
     

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32

Equilibrium responder directions

  • Utricle - Horizontal (linear) acceleration
  • Saccule - Vertical (linear ) acceleration
  • (3) Semicircular canals - angular acceleratoin 

33

Diagram of ear endolymph/perilymph and structures

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34