Ears Flashcards
what are the main three components of the ear?
outer ear
middle ear
inner ear
what is the external auditory canal lined with?
lateral part - skin, cartilage
medial part - skin, bone
what separates the external auditory canal from the middle ear?
tympanic membrane
what are the three layers of tympanic membrane?
skin
fibrous layer
respiratory layer
what allows a connection between the tympanic membrane and the inner ear?
ossicles
what are the three ossicles of the middle ear? where are they?
malleus - attached to tympanic membrane
stapes - attached to oval window of inner ear
incus - in between malleus and stapes
what are the two main areas of the tympanic membrane called?
pars flaccida (top) pars tensa (bottom)
what part of which bone surrounds the middle and inner ear?
petrous part of temporal bone
with what structures does the middle ear have direct communication?
mastoid process
nasopharynx via eustachian tube
what are the two muscles found in the middle ear, and what is their function?
tensor tympani - dampens down loud noises by adjusting tympanic membrane tension
stapedius - stabilises the stapes
what does a pinna hematoma lead to?
cauliflower ear
which part of the external auditory canal produces wax?
the lateral part
what is the difference in appearance between the lateral and medial parts of the external auditory canal?
lateral has cilia and earwax producing glands
medial has no cilia and doesn’t produce wax
what is the middle ear lined with?
respiratory epithelium
what nerve supplies the inner ear?
vestibulocochlear nerve (CNVIII)
what are the three chambers in the cochlea called?
scala vestibuli
scala media
scala tympani
what fluid is contained in the chambers of the cochlea?
scala vestibuli - perilymph
scala media - endolymph
scala tympani - perilymph
what is the Organ of Corti?
a structure with hair cells which relay soundwave pressure information to the nerve fibres
what’s the name of the facial nerve branch which passes through the middle ear?
chorda tympani
what is cholesteatoma?
abnormal build up of skin in the middle ear
what are 5 important structures near the middle ear, which may be clinically important?
- facial nerve
- mastoid process
- sigmoid sinus/internal jugular vein
- internal carotid artery
- brain
what is the general sensory supply to the middle ear?
tympanic branch of glossopharyngeal nerve (CNIX)
what is the general sensory supply to the posterior part of the external auditory canal?
auricular branch of vagus (CNX)
what is the general sensory supply to the anterior part of the external auditory canal?
facial nerve (CNVII)
what are the functions of the inner ear labyrinth?
hearing and balance
what are the components of the inner ear involved in balance?
semicircular canals
utricle
saccule
what are the functions of the three components of the labyrinth in the inner ear?
semicircular canals - detect head rotation
saccule - detect vertical acceleration
utricle - detect horizontal acceleration
what type of sounds are detected at which point of the cochlea and why?
low pitched sounds - at the start (short hair cells)
high pitched sounds - at the end (long hair cells)
