Flashcards in Ear and auditory canal anatomy Deck (22):
What are the borders of the outer ear?
from the external auditory meatus to the tympanic membrane
What is the sensory innervation to the external auditory meatus?
Auriculotemporal nerve (branch of V3-mandibular) supplies the anterior/superior surfaces and the external tympanic membrane. Vagus nerve suplies the posteroinferior parts
Where can ear pain refer to and why?
can refer pain to teeth via the inferior alveolar nerve (branch of the mandibular)
Looking at the tympanic membrane where is the cone of light usually found? displacement from here can indicate what?
usually in the antero-inferior quadrant -> high pressure in the middle ear can alter the concavity of the membrane and cause displacement
What are the boundaries of the middle ear?
tympanic membrane to oval window (in petrous part of temporal bone)
What is the epitympanic recess? what is significant about this space?
superior to tympanic membrane within the middle ear- communicates with the mastoid air cells therefore infection can spread and fester in these poorly drained air cells.
What is the auditory tube made up of?
1/3rd = bone (closest part to middle ear) 2/3rds cartilage - can change positions using muscles (ie how we 'pop' our ears)
Why are children more prone to middle ear infections?
auditory/eustachian tube is more horizontal -> easier for bacteria to migrate upwards and harder for it to drain
What are gromets?
small devices allowing communication (through the tympanic membrane) between the atmosphere and the middle ear allowing for equalization and drainage
What are the ossicles? what are the functions?
small bones within the middle ear that attach to the tympanic membrane (Malleus) and the opening to the inner ear (Oval window - Stapes)
Name the 3 ossicles
Stapes, Incus, Malleus
What muscles attach to the ossicles? What are their functions?
Tensor Tympani attaches to Malleus, Stapedius attaches to Stapes. Pull on and thus dampen the vibrations to prevent damage to the hearing receptors
What nerve innervates Stapedius?
S for Seventh -> facial nerve CNVII
What nerve innervates Tensor Tympani?
T for Trigeminal
What is the promontory? why is it useful?
bulge seen when looking laterally with TM removed -> good marker for oval and round windows
What are the boundaries of the inner ear?
from the oval window to the cavities within the petrous part of the temporal bone
Immediately after the oval window is what space? What is its function?
the vestibule -> made up of the Saccule and Utricle. Sensory receptors here are responsible for detecting head position (static equilibrium)
What kind of fluid is within the bony labyrinth?
What fluid is contained within the membranous labyrinth?
What are the semicircular canals?
Anterior, horizontal and posterior -> each at right angles to the other two
What part of the inner ear is involved in dynamic equilibrium?
Ampulla = swellings at the end of each semicircular duct