Lecture 27 RH Flashcards
What is the eardrum?
tympanic membrane
What is the middle ear?
space between tympanic membrane and petrous part of temporal bone is called the middle ear.
What is the inner ear?
Space within petrous part of temporal bone is the inner ear
What is the outer ear?
Before the tympanic membrane is the outer ear.
How is loss of balance controlled?
In the petrous part of the temporal bone is a portion that allows us to control balance.
What are the components of the outer ear?
auricle: cartilaginous and collects sound. Tragus is the flap anterior to the ear canal.
How is sound able to reach the middle and inner ear?
Sound is transmitted through external auditory meatus to the tympanic membrane.
What is the structure of the external acoustic meatus?
External acoustic meatus is supported laterally (lateral 1/3) by cartilage and medially by the temporal bone. It is lined by hairy skin and cerumen glands.
What is the function of cerumen?
prevents maceration of skin with water.
What does “maceration” mean?
Maceration is defined as the softening and breaking down of skin resulting from prolonged exposure to moisture.
What nerves supply the external auditory meatus?
Nerve supply to external auditory meatus is done via several nerves:
posterior+inferior by vagus
anterior +superior by auriculotemporal nerve (from V3 of trigeminal nerve)
Where are other locations that pain of the ear could be referred to?
Pain of ear could be referred to other locations that the mandibular division of the trigeminal nerve innervates. (eg teeth)
*Pain from teeth could be referred to the ear.
What is the indentation on the tympanic membrane called?
Indentation on the tympanic membrane formed by the malleus of the inner ear.
What shape does the tympanic membrane have?
tympanic membrane is concave laterally.
What causes the concavity seen in the tympanic membrane?
Concavity depends on pressure within the middle ear relative to the outer ear.
What is the cone of light of the tympanic membrane?
Cone of light can be seen at the antero inferior quadrant. If that light is not visible then that means the pressure difference is indicating a problem with the middle ear.
What is the epitympanic recess? What is the problem with it?
Communicates with mastoid air cells and so infection of nasal cavity and auditory tube can go to mastoid air sinuses.
What are the cavities of the middle ear?
middle ear is split up into 2 compartments:
Tympanic cavity proper (immediately medial to tympanic membrane)
Epitympanic recess: superior to the tympanic cavity.
How does the nose/mouth connect to the ear’s tympanic cavity?
Pharynx is connected to the tympanic cavity in the ear via the auditory tube (aka pharyngotympanic tube)
What is pharyngotympanic tube made of?
Primarily cartilaginous with the exception of the tympanic cavity which is embedded in bone.
What direction does the pharyngotympanic tube point?
anteriorly and inferiorly
What is a problem that arises with having the pharyngotympanic tube between the nasopharynx and the tympanic cavity?
because of the downwards opening infection could travel between cavities
What is the problem of inflammation on the ear?
Inflammation causes ossicles to be interrupted and pressure increase could push out the tympanic membrane and potentially damage it.