Ear

Question 1

What are the functions of the external ear?

Answer 1

• protects the eardrum and collects sound waves and sends to tympanic membrane

Question 2

what is the function of the middle ear?

Answer 2

• function to amplify and convert sound waves into mechanical energy

Question 3

What is the function of the inner ear?

Answer 3

• receives mechanical energy and converts it into a fluid wave
• receptors of the inner ear respond to the fluid vibrations for the perception of sound “interpret”
• sensory cells for hearing

Question 4

What funnels sound into tympanic membrane?

Answer 4

pinna

Question 5

The external canal is surrounded by skin with glands that produce what?

Answer 5

• cerumen
  
  • protective function
  • can get impacted

Question 6

What seperates the external from middle ear?

Answer 6

Tympanic membrane

Question 7

Label these portions of the external ear

Answer 7

Question 8

What does sensory innervation of the external ear?

Answer 8

Question 9

What is the outside and inside of tympanic membrane composed of?

Answer 9

• skin is external
• mucous membrane is internal
• moves in response to air vibrations

Question 10

What bone moves when the tympanic membrane moves?

Answer 10

• Malleus
• Pars tensa:
  
  • Handle of malleus (manubrium) is embedded in tympanic membrane on the medial side of the membrane
  • manubrium draws membrane medially creating a depression
    
    • the greatest point of concavity = umbo
  • cone of light (base projected anteroinferiorly in a healthy ear) when viewed with an otoscope
    
    • caused by noce

Question 11

What bone is the middle ear located?

Answer 11

petrous bone

lined with mucous membrane

Question 12

What is the tube that:

• equalizes pressure between middle ear and external environment
• allows for drainage of middle ear

Answer 12

Pharyngotympanic tube

Question 13

What are the regions of the middle ear cavity?

Answer 13

Typanic cavity

Epitympanic cavity

Question 14

WHat are the contents of the middle ear cavity?

Answer 14

• malleus, incus stapes
• synovial joints between articulations
• manubrium embedded in tympanic membrane
• footplate of stapes on oval windom
• conduct vibrations from tympanic membrane to fluid filled chamber of the cochlea

Question 15

What CN innervates stapedius muscle?

Answer 15

• CN VII
• pulls it off oval window

Question 16

What CN innervates tensor tympani muscle attached to malleus?

Answer 16

CN V3

• pulls it off tympanic membrane

Question 17

What is the purpose of the stapedius and tensor tympani muscle?

Answer 17

• Both contract reflexively in response to loud sound
  
  • tense the tympanic membrane or
  • move foot plate of stapes off oval window of cochlea
  • dampen the sound and preventing damage to inner ear

Question 18

What nerve does taste to anterior 2/3 of the tongue and parasympathetic fibers to sublingual and submandibular gland

• it is inside the tympanic cavity

Answer 18

Chorda tympani is a branch of facial nerve (CN VII)

Question 19

What nerve joins with nerves from carotid plexus to form lesser petrosal nerve carrying parasympathetic fibers to the parotid gland?

Answer 19

Tympanic nerve (CN IX)

Question 20

What is the thin plate of bone separating tympanic cavity from dura mater on floor of mid cranial fossa?

Answer 20

Roof-tegmen tympani

Question 21

What is the layer of bone separating the tympanic cavity from superior bulb of internal jugular vein (posteriorly)?

Answer 21

Floor of tympanic cavity

Question 22

What part of the tympanic cavity is the tympanic membrane:

• handle of malleus attached to tympanic membrane
• chorda tympani nerve crosses between incus and malleus
• head of malleus located in the epitympanic recess superiorly

Answer 22

Lateral wall

Question 23

What is the outermost coil of the cochlea, tympanic plexus on its wall?

Answer 23

Promontory

Question 24

What is medial to footplate of stapedius, above and behind promontory

Answer 24

Oval window (fenestra vestibuli)

Question 25

What can occur in these regions

Answer 25

Your tonsil can enlarge and close off pharyngotympanic tube and you are more susceptible to middle ear infections

Question 26

Where are the mastoid air cells located?

Answer 26

Mastoid antrum

Question 27

Describe the course of facial nerve

Answer 27

1. Facial nerve enters internal auditory meatus along with vestibulocochlear nerve 2. geniculate ganglion contains sensory nerve cell bodies for special sense to the taste buds to anterior 2/3 the tongue 3. Greater petrosal carrying parasympathetic fibers to pterygopalatine ganglion 4. chorda tympani special sense to taste buds on anterior 2/3 of tongue (lingual, a branch of V3, carries general sense to anterior 2/3 of the tongue 5. lesser petrosal carrying parasympathetic fibers from glossopharnygeal (CN IX) and sympathetic fibers from carotid plexus

Question 28

What is the dense bone that encases the sense organs for hearing and balance?

Answer 28

Otic capsule

Question 29

What is the fluid within the membranous labryrinth? * Similar in compostion to intracellular fluid * produced by specialized cells in the membranous labyrinth * Membranous labrynth: * utricle and saccule * semicircular ducts * cochlear duct

Answer 29

Endolymph * can be absorbed and stored from endolmphatic sac located under the dura in the posterior part of the petrous temporal bone

Question 30

What is the fluid between the bony and membranous labyrinth? * similar in compostion ot CSF * empties via cochlear aqueduct into subarachnoid space

Answer 30

Perilymph

Question 31

What contains the sensory receptor cells?

Answer 31

Spiral organ of corti

Question 32

What do the specialized cells in the macula of the utricle sense?

Answer 32

Linear acceleration in the horizontal plane * forward and back * left to right

Question 33

What do the specialized cells in the macula of the saccule sense?

Answer 33

Linear acceleration in the vertical plane * up-down movement