Chapter 6-7

Question 0

Names of the outer ear

Answer 0

Pinna / Auricle

Question 1

Wherein the 8th cranial nerve located

Answer 1

Inner ear

Question 2

What is the pinna and what the framework is made up of

Answer 2

• flap-like appendage on sides on ears

- framework made-up of cartilage

Question 3

What does the pinna funnel into

Answer 3

The EAC , external auditory canal

Question 4

What is the External auditory canal made-up of

Answer 4

Lateral side made up go cartilage , and leads medially to bone

Question 5

What’s is the (EAC) External Auditory Canal ?

Answer 5

• bent tube 25/35mm long ( 1-1 1/4 inches)
• 5-7 mm in diameter
• covered in skin

Question 6

Cartilage portion secretes …

Answer 6

Cerumen

Question 7

What does the outer ear effect ? (3)

Answer 7

• protection for delicate middle and inner ear structures
• enhancement go mid-high frequency region ( improves sensitivity)
• improves in directional hearing

Question 8

Why is there improved sensitivity ?

Answer 8

Because its a tube with 1 open and 1closed end

- standing wave starts at odd integer multiples of frequencies with wave length of 4x length of tube

Question 9

How can you find the frequency of a external auditory canal

Answer 9

• average adult canal is approximately 25 mm

- the frequency = c (344) / 4X length of the canal

Question 10

When is there a sound pressure gain in the EAC ?

Answer 10

Sound pressure gain at the medial end of pipe of about 12-15 dB at around 3400 Hz

Question 11

How does the outer ear aid in directional hearing?

Answer 11

• two ears on opposite sides of the head
• Head ( .18m in diameter ) and torso create a baffle effect
• sound from air travels through EAC

Question 12

What restriction are present on hearing

Answer 12

• Frequency below 1900 Hz (344/.18) are diffracted around head
• > 1900 Hz are reflected => constructive reinforcement
• cues to localize sound
  
  • complex , involve differences in time of arrival and level between the ears

Question 13

What leads to the beginning if the middle ear

Answer 13

Tympanic membrane

Question 14

Characteristics of TM ; diameter , location , substance and sections

Answer 14

• 8-9 mm in diameter
• medially end = eustation tube
• laterally near EAC
• layered cone shaped membrane
• superior area is the location of pars flaccida (2 layered)
• inferior layer locates the pars tensa (3 - 4 tissue layers )

Question 15

What is pars tensa made up of ?

Answer 15

(Sandwich) made up of skin and mucosa with fibrous tissue inter twining making it stiff

Question 16

What ear has the head of the malleus facing 11:00 o’clock ?

Answer 16

Left ear

Question 17

What ear has the head of the malleus facing 1:00 o’clock ?

Answer 17

Right ear

Question 18

What ossicles are visually present while looking at the TM from and exterior view ?

Answer 18

• the short process of the malleus
• incus
• handle of the malleus
• sometimes the incus

Question 19

What three middle ear ossicles are all attached ? Which attaches to the tympanic membrane ?

Answer 19

The malleus is attached to the tympanic membrane which also attaches to the incus and the stapes

Question 20

What are the position of the ossicles on the malleus , starting laterally leading to the medial most part connecting to the stapes ?

Answer 20

Umbo - handle of malleus (aka manubrium) - head of malleus

Question 22

What are the cavities called that are located in the middle ear , listed superior to inferior ?

Answer 22

• tympanic cavity
• epitympatic recess (aka attic) > aditus : opening to two landmarks
• mastoid Antrum

Question 23

What is the middle ear made up of ?

Answer 23

ME bones, ligaments and muscles

Question 24

What does the middle ear connect to , what does it do ?

Answer 24

ME connects to nasopharynx by eustachion tube which ventilates and drains the middle ear space

Question 25

What is the difference in the eustachion tubes in children and adults , what difficulties occur ?

Answer 25

They are horizontal in children , adenoids swelling can cause difficulties because they may block tubes …. Causes an uneven distribution of pressure due to tubes

Question 26

What happens when eustachion tubes are not working ?

Answer 26

If tube is blocked / swelling occurs it creates a negative pressure because air can’t enter . The ME secretes fluid to fill the space

Question 27

What is located inside of the tympanic cavity ? ( 6) walls

Answer 27

Lateral wall: tympatic membrane
Anterior wall : carotid wall ( caractid artery)
Posterior wall : mastoid wall (aditus location)
Superior wall : tegmental wall ( thin plate of bone)
Inferior side : jugular wall (jugular vein below)
Medial side: labyrinth wall (oval/ round window)

Question 28

Ossicular chain and parts of the each piece ?

Answer 28

• malleus ( head & manubrium)
• incus ( body & legs)
• stapes (head, crura and footplate)

Question 29

Facts about stapes , where does it insert, how large is the footplate .

Answer 29

• smallest bone in the human body
• foot plate sits in the oval window in the inner ear , supported in place by the annular ligament
• area of foot plate is approximately 3.2mm^2

Question 30

What influences the movement of the ossicles in the middle ear?

Answer 30

• ligaments suspend the ossicles in cavity
• ME muscles that influence ;
  1. Tensor tympani
  2. Stapedius

Question 31

Tensor tympani

Answer 31

Attached to the manubrium , innervated by the 5th cranial nerve

• if muscles contracts it limits movement for ossicles

Question 32

Stapedius

Answer 32

Attached to the head of stapes , innervated by the facial nerve 7

• if muscles contract it limits movement

Question 38

How big is the middle ear and what does it hold ?

Answer 38

Two cubic cm , cavity comprising three air-filters