27 - Ear Flashcards
1
Q
Where is the internal meatus located?
A
Petrous part of the temporal bone
2
Q
Where is the external acoustic meatus located?
A
Lateral to the carotid canal
3
Q
What makes up the external ear?
A
- auricle
- external acoustic meatus
- tympanic membrane
4
Q
What makes up the middle ear?
A
- tympanic cavity
- malleus, incus and stapes
- tensor tympani, stapedius
- auditory tube
5
Q
What makes up the inner ear?
A
- vestibule
- semicircular canals
- cochlea
6
Q
How do the ossicles transmit sound?
A
Mechanically by vibrations
7
Q
Describe the auricle.
A
- elastic cartilage
- funnels sound into the external acoustic meatus
- helix, tragus and lobule are notable cartilaginous structures
8
Q
What is the sensory innervation of the auricle?
A
- great auricular
- auriculotemporal
9
Q
Describe the external acoustic meatus.
A
- 2.5cm in length
- cartilaginous lateral 1/3, bony medial 2/3
- stratified squamous epithelium that contains ceruminous glands that secrete ear wax
10
Q
Describe the tympanic membrane.
A
- held by a fibrocartilaginous ring
- at an angle facing downwards and anteriorly
- 1cm in diameter
- attached to the handle of the malleus, this forms the umbo
11
Q
What is the cone of light?
A
Reflection of the otoscope indicating a healthy middle ear
12
Q
What is the function of the middle ear muscles?
A
- dampen vibrations (protective)
- reduce movement of the ossicles
13
Q
What is the attachment and action of the tensor tympani?
A
- attaches to malleus and pulls the tympanic membrane taught
- this reduces amplification of loud sounds
14
Q
What is the innervation of tensor tympani?
A
CN V3
15
Q
What is the innervation of stapedius?
A
CN VII
