Week 6.0 - Ear Flashcards
Name the components of the middle ear
- Auditory ossicles (malleus, incus, stapes)
- Mastoid air cells
- Tympanic cavity
- Eustachian tube
- Tensor typani
- Stapedius
Name the components of the inner ear
- Semicircular canals
- Vestibular labyrinth
- cochlear
Why is the shape of the pinna significant?
-Grooves act to funnel sound and amplify into EAC to vibrate tympanic membrane
How do you examine the ear?
- Compare both sides at front, sides, behind and inside
- In adults pull up, back and out
- In children pull down, back and out
What is a pinna haematoma? Why is it serious?
- Haematoma (collection of blood) between cartilage and perichondrium
- Prevents oxygenation of cartilage resulting in avascular necrosis
Name 3 common conditions of the external auditory canal
- Foreign body
- Conduction block by wax
- Otitis externa
Describe the tympanic membrane
- Waterproof barrier consisiting of pars flaccida and pars tensa with the fibres arranged from midline outwards
- Handle of malleus pressed on posterior of membrane
- Umbo
What is a tympanic perforation? Give the most common 2 causes
- Hole in the tympanic membrane
- Can be central or subtotal
- Often caused by trauma or secondary to infection
What is the difference between pars flaccida and pars tensa of the tympanic membrane?
-Pars flacida fibres are haphazerdously arranged
Name the auditory ossicles
-Malleus, stapes and incus
How are the auditory ossicles arranged?
-Handle of malleus presses into tympanic membrane, head of malleus bound to body of incus, long process of incus attaches to head of stapes, foot plate of stapes plugs into oval window of inner ear
What is the result of dysfunction of the eustachian tube?
-Negative pressure in the middle ear causing tympanic retraction
What is the epitympanic recess?
-Upper portion of middle ear where auditory ossicles are
Name the two muscles of the middle ear, their innervation, and what they are attached to
- Tensor typani -> CNV -> malleous
- Stapedius -> CNVII -> Stapes
What is the function of the muscles in the middle ear?
-Damper sounds to protect against loud noise