Flashcards in H&N 7.1 The ear. Deck (69)
What are the functions of the ear?
(-equilibrium of pressure)
How can the ear be divided up into parts?
What makes up the outer ear?
-external aurditory meatus
-lateral surface of tympanic membrane
What's another name for the auricle?
What are some common signs/symptoms of pathology of the ear?
loss of hearing
in what bone is the ear?
The petrous part of the temporal bone
What are the anatomical parts of the pinna?
What is the pinna made up of?
Cartilage, fatty tissue and skin.
What is the function of the auricle?
To 'catch' sound and direct it within the ear, and to the tympanic membrane.
What abnormalities can occur in the pinna of the ear?
-facial nerve palsy (leads to vesicles and inflammation)
What is a pinna haematoma?
What causes it?
Due to blunt trauma, there is a build up of blood between the cartilage and overlying perichondrium. This looks like a big bulging ear.
What are the risks of the pinna haematoma?
The cartilage normally recieves its nutrients from the perichondrium, so when this is stripped away by the collection of blood, the cartialge can undergo necrosis (pressure necrosis due to the pressure exerted by the blood).
This can lead to a cauliflower ear.
Why does a cauliflower ear develop?
Pinna haematoma has lead to necrosis of the cartilage of the ear.
New cartilage is laid down but in an uncoordinated fashion, which along with fibrosis leads to an asymetrical, funky looking ear.
How would you treat a pinna haematoma?
promtly draining the blood and ensuring there is no reaccumulation and the cartilage and perichondrium are reapposed.
Give some features of the external accoustic meatus?
-it's a skin lined cul-de-sac.
-it contains hairs and wax
-it is around 2.5 cm long
-it is sigmoid in shape
What is the structure of the external auditory meatus?
outer 1/3 made from cartilage.
inner 2/3 made from bone.
How does the ear clean itself?
dead skin cells and other debris get deposited within the external ear canal.
This collects and forms wax.
The hairs move this wax out of the ear.
What is the process of shedding skin/the outer layer of cells known as?
What is the function of wax?
it helps to prevent objects from enterring deeper into the canal.
What are some common conditions affecting the external accoustic meatus?
-accumulation of wax (can lead to conductive hearing loss)
What is otitis externa?
What is a common cause?
infection of the external accoustic meatus.
Causes inflammation, some discharge
How would you treat otitis externa?
Antibiotic/steroid drops for the ear.
What should you be able to see when looking into the ear on the tympanic membrane?
-handle of malleus and umbo
-long process of incus
-parsa tensa (tightly stretched membrane)
-parsa flacid (looser membrane)
-cone of light
What abnormalities might you see of the tympanic membrane?
-perforation (eg due to cotton bud)
-bulging and loss of features (otitis media)
-straw coloured fluid behind (glue ear)
-may be pulled inwards (negative pressure of middle ear, due to dysfunction of eustachian tube)
-may see grommits.
What are the main anatomical components of the middle ear?
-tensor tympani muscle
What anatomical relations does the middle ear have?
-facial nerve (and chorda tympani runs through tympanic cavity)
-mastoid air cells
-internal jugular vein (inferiorly)
-internal carotid artery (anteriorly)
What are the 3 osccicles?
What's the function of the ossicles?
The malleous is attached to the tympanic membrane, and the others forma chain, attaching the inner ear.
They vibrate when the tympanic membrane does, and amplify the vibration, so we can hear sound.
What muscles are present in the ear?
What are their innervations?
What is their function?
-stapedius (facial nerve)
-tensor tympani (mandibular nerve, Vagus)
They contract in response to loud noise, to dampen the sound and protect the hearing apparatus.
Known as the acoustic reflex.