Anatomy and Histo of Ear Brauer

Question 1

What arteries and nerves supply the auricle of the ear?

Answer 1

Posterior auricular and superficial temporal arteries and sensory nerves via greater auricular nerve and auriculotemporal nerve

Question 2

What epithelium lines the inside and outside of the tympanic membrane?

Answer 2

Inside is simple cuboidal and outside is stratified squamous

Question 3

What innervates the tympanic membrane?

Answer 3

External surface of it is innervated by the auriculotemporal nerve and the internal surface is by a branch from V3 and small auricular branch of the vagus

Question 4

What causes a ruptured tympanic membrane?

Answer 4

Abnormal increase in medial ear pressure due to fluid or barotrauma. External trauma can also cause this

Question 5

What are the boundaries of the middle ear?

Answer 5

Roof: tegmental wall Floor: Jugular Lateral: Membranous wall Medial: Labyrinthine wall Posterior: Mastoid wall Anterior: Carotid wall- located near the opening of pharyngotympanic tube and canal for tensor tympanii

Question 6

What is the significance of the pharyngotympanic tube?

Answer 6

It equalizes pressure in the ears and connects the tympanic cavity with the nasopharynx.

Question 7

What opens the pharyngotympanic tube?

Answer 7

Levator veli palantine, tnesor veli palatine, salpingopharyngeus

Question 8

The posterior lateral part of the pharyngotympanic tube is ____ and the remainder is made of _____.

Answer 8

Bonne and elastic cartilage

Question 9

Which statement is correct:

1. The incus attaches to the malleus which will then attach to the stapes at the round window
2. The bones are found in different orders in different people
3. The malleus attaches to the incus which will then attach to the stapes at the round window
4. The incus attaches to the malleus which will then attach to the stapes at the oval window
5. The malleus attaches to the incus which will then attach to the stapes at the oval window

Answer 9

The malleus attaches to the incus which will then attach to the stapes at the oval window

Question 10

What innervates the tensor tympanii muscle, what is its function, and what ossicle does it associate with?

Answer 10

• CN V
• Pulls on the handle of the malleous to tense the membrane and reduce amplitude
• Inserts on the malleous handle

Question 11

What innervates the stapedius, what is it’s action, and what ossicle is it associated with?

Answer 11

• CN VII
• Pulls stapes posteriorly tighthening the annular ligament and atatching it to the window.
  
  • reduces oscillatory range and prevents excessive movements of the stapes
• Stapes

Question 12

What is otitis media?

Answer 12

Ear ache with fluid or pus in the middle ear due to inflammation or infection. The tympanic membrane will be red and bulging and fluid may be visible. If left untreated it can damage the auditory ossilcles and impair hearing

Question 13

What is mastoiditis?

Answer 13

Infection of mastoid cells that can spread into the cranial fossa via the petosquamous cranial suture. Treat with antibiotics

Question 14

What makes up the inner ear?

Answer 14

1. Bony Labyrinth made up of semicircular canals vestibule and cochela
   
   1. Membranous Labyrinth within the bony labyrinth

Question 15

Where is perilymph found and what is its compositon?

Answer 15

• Found between the bony and membranous labyrinths
  
  • Similar to CSF it drains into subarachnoid space

Question 16

Where is endolymph found and what is it’s composition?

Answer 16

• Found within the membranous labyrinth
• High K Low Na
• Originates from the stria vascularis and drains into venous sinuses of the dura mater

Question 17

If the hair cells move toward and away from the kinocilium what happens? What innervates hair cells??

Answer 17

• K channels open if moves towards
• Close if move away
• Efferent and afferent nerves

Question 18

Describe the divisions of the cochelar duct.

Answer 18

1. Most superior is the scala vestibuli which contains perilymph. The fluid is moved by the stapes at the oval window and it is continuous with the scala tympani
2. Scalea media is the middle portion which contains the endolymph. This compartments is also called the cochlear duct
   
   1. The stria vascularis is lateral wall of this compartment and produces endolymph
3. Scala tympani is the most inferior compartment and it also contains perilymph. It is connected to the round window.

Question 19

How does the organ of corti allow us to hear? (describe the composition)

Answer 19

It is made up of hair cells phalangeal cells for support and pillar cells to support the membranes. The hair cells are made of stereocilia which are embedded in the tectorial membrane. The basilar membrane will vibrate with sound which causes the stereocilia to move opening the K channels.

Question 20

Describe the path sound takes starting at stapes.

Answer 20

The stapes will move the oval window which causes the perilymph to create waves. The waves will distort the vestibular membrane which will cause a wave within the scala media. This wave will displace the basilar membrane distoring the hair cells. The pressure continues to the scala tympani and moves to the round window where it exits.

High frequency pitches will be heard closer to the windows while low frequency sounds will travel further.

Question 21

What is conductive hearing loss?

Answer 21

It is loss due to fluid build up in the middle ear, otitis, excessive wax or otoscleosis. It is impacting the outer or middle ear.

Question 22

What is sensorineural hearing loss?

Answer 22

Reduction in sound level due to damage to inner ear or auditory nerve. It will affect heraing at differnet frequencies and intensities. It is related to age and induced by noise.

Question 23

What causes a central hearing loss problem?

Answer 23

Problems in the CNS

Question 24

What senses rotaional velocity and describe the composition.

Answer 24

Semicircular canals and the ampulla

• Each canal is in a different axis and filled wiwth endolymph and connected to the utricle
• The ends of the canals have an ampulla with a cupulla (gelatinous cap)
• The cupula will be displaced by the endolymph due to movement

Question 25

What structures sense gravity and linear acceleration? Describe the compositon.

Answer 25

Utricle and Saccule

• Vestibule contains the saccule and utricle
• Each of these contains a macula which is made of an otolithic membrane covered with calcium crystals called otoconia.

Question 26

What is Meniere’s Syndrome?

Answer 26

It is associated with an increase in the volume of endolymph which leads to abnormal signaling. The cause is unknown. Those with this will experience vertigo, tinnitus and flucutating hearing loss. If mild can be treated with medicine and if severe may need surgical ablation of labyrinthe. This is risky bc there could be permanent hearing loss.

Question 27

What three nerves are in the internal acoustic meatus?

Answer 27

Vestibular

Acoustic

Facial