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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)

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 

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

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

22

Membranous Labyrinth

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

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)

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

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 
     

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

34