Neurology - ears Flashcards
What makes up the external part of the ear?
Pinna (cartilage ear)
External canal
Ear drum/tympanic canal
What makes up the middle ear
Tympanic canal with ossicle bones
>malleus>incus>stapes
Oval window
Round window
Eustachian tube
What does the ossicle bones do?
They vibrate against the oval window to transmit sound
What do the round window and eustachian tube do?
Help dissipate pressure in loud systems.
What is the inner ear?
Bone canal with:
Utricle
Vestibule and saccule
Semicircular canals
Cochlea
Auditory nerve
What is the cochlea?
The hearing part of the ear. Turns 2.5 times like a snail.
It is filled with fluid, split into three tubes. The apex for low pitch and base for high pitch.
What are the three layers of the cochlea?
Scala vestibuli (perilymph) - sits on top, tough layer.
Scala media (endolymph) - has the organ of corti in it
Scala tympani (perilymph) - sits on base with basilar membrane, where organ of corti sits on
What is the organ of corti?
Sits on the basilar membrane of the scala tympani. On this basilar membrane there are millions of hair cells, and on top of these are sterocilia which connect with the tectorial membrane.
A tectorial membrane hovers over this basilar membrane.
How is sound transmitted?
A sound causes vibrations down the ear canal, leading to the ossicle bones to vibrate.
This wave leads to the endolymph moving, and a deflection of basilar membrane.
This causes inner hair cells to move across the tectorial membrane and bend.
This leads to a signal along the vestibularcochlar nerve (CNVIII) to the temporal cortex.
What is the vestibular system?
For balance
What do the semicircular canals do?
Detect angular acceleration nodding, shaking and tilting
How do the SCC detect?
They are filled with endolymph and have amullary cupula at the entrance of each loop. The cilia of the hair cells are embedded in this gelatinous cupular. When the head moves the gelatine slides.
What does the maculae do?
The maculae is the utriculus (horizontal) and saccululs (vertical) and detects linear acceleration.
How does the maculae do this?
Utricle - horizonal plane
