The Vestibular Apparatus
.
Definition
The portion of the ear which assists balance
Two parts bony labyrinth and membranous labyrinth
Bony labyrinth
A cavity within the temporal bone with periosteum
Membranous labyrinth
A membranous bag inside the bony labyrinth
Between the bony labyrinth and the membranous labyrinth there is a fluid called perilymph
Inside the membranous labyrinth - fluid - endolymph.
The parts of the bony labyrinth are :-
1 vestibule
1 cochlea
3 semicircular canals
Vestibule
Part nearest the middle ear
Contains oval and round windows in its lateral wall.
Cochlea
Snail shaped
Broad base
Continuous with vestibule
Spirals +
At the centre of the spirals there is bone
The Semicircular Canals
3 tubes
one in each of the three planes of space
they are continuous with the vestibule
The parts of the membranous labyrinth are
This membranous sac is separated from the bony labyrinth by perilymph. It contains endolymph. (perilymph between the bone and the membranous sac and endolymph within the sac)
The vestibule containing the Utricle & Saccule,
The Cochlea
The semicircular canals - anterior, posterior and lateral
The membranous cochlea contain basilar membrane with neuroepithelial cells and their nerve fibres organ of Corti : sensory - sound observed by the nerve of hearing & transmitted to the brain
- Describe the structure of the ear.
- Short notes on structure and functions of middle ear and vestibular apparatus
