Conference 26: temporal bone

Question 1

Which structure allows infection to spread from nasal cavity and pharynx to the middle ear cavity

Answer 1

auditory tube

Question 2

Why do children get middle ear infections (otitis media) more often than adults?

Answer 2

1. Their auditory tube is more horizontal
2. Their auditory tube is shorter
3. Children have weak immune systems

Question 3

How is the Tympanic membrane oriented?

Answer 3

obliquely

slopes medially going posterior to anterior and going superior to inferior

Question 4

Which are the longest walls of the tympanic membrane

Answer 4

anterior and inferior

Question 5

What is the normal appearance of the tympanic membrane?

Answer 5

shiny, pearly gray and shaped like a funnel

Question 6

What ossicle presses up against the tympanic membrane

Answer 6

malleus

Question 7

What nerve innervates the mucosa of the middle ear cavity and is therefore is responsible for the pain felt during otitis media?

Answer 7

tympanic branch of the glossopharyngeal nerve

Question 8

What is the roof of the middle ear cavity?

Answer 8

middle cranial fossa

Question 9

floor of middle ear cavity?

Answer 9

internal jugular vein within the jugular foramen

Question 10

lateral wall of the middle ear cavity?

Answer 10

1. tympanic membrane

2. chorda tympani

Question 11

medial wall of the middle ear cavity?

Answer 11

1. facial nerve in facial canal
2. oval window
3. round window
4. promentory

Question 12

anterior wall of middle ear cavity?

Answer 12

Tensor tympani
auditory tube
carotid canal

Question 13

what is conduction deafness?

Answer 13

deafness caused by interruption of the sound transmission into the inner ear (often caused by middle ear disease)

Question 14

what could cause interruption of the ossicles conducting sound waves?

Answer 14

1. fluid from infection
2. tumor in middle ear cavity
3. bone disease –> osteosclerosis

Question 15

What is sensorineural deafness

Answer 15

deafness caused by lesion to the receptor (hair cells), vestibulocochlear nerve, or the terminus in the brain (low pons)

Question 16

Describe the sound transmission pathway starting with sound waves entering the external auditory canal?

Answer 16

sound waves hit tympanic membrane and make it vibrate. the vibrating tympanic membrane starts the ossicles into motion and when the stapes is in motion it moves the oval window starting a fluid wave through the fluid of the cochlea. This fluid wave triggers hair cells and conducts an electrical signal to brain.

Question 17

what does hyperacusis mean?

Answer 17

sounds appear louder than they really are

Question 18

If a patient has hyperacusis, what 2 nerves could possibly be lesioned?

Answer 18

1. facial nerve

2. V3

Question 19

What are the two muscles that dampen loud noises

Answer 19

1. stapedius

2. tensor tympani

Question 20

How do these muscles dampen loud noises?

Answer 20

When the stapedius or tensor tympani contract they restrict movement of the ossicles

Question 21

What do the skeletomotor fibers of the facial nerve innervate?

Answer 21

1. stapedius muscle
2. muscles of facial expression
3. Stylohyoid
4. Posterior belly of digastric

Question 22

What kind of fibers are in the Chorda Tympani nerve?

Answer 22

1. Taste

2. secretomotor

Question 23

What do the secretomotor fibers of the facial nerve innervate?

Answer 23

1. Lacrimal gland & palate and nasal cavity (via greater petrosal nerve)
2. sublingual and submandibular glands (via chorda tympani)

Question 24

What do the taste fibers of the facial nerve innervate?

Answer 24

anterior 2/3 of the tongue

Question 25

What two fiber types have their cell bodies located in the geniculate ganglion?

Answer 25

taste and cutaneous sensation

both sensory fibers

Question 26

What part of the skin does the facial nerve to cutaneous innervation to?

Answer 26

the skin over the mastoid process