4. Bony labyrinth
3 parts
Vestibule
Semicircular canals
Cochlea
Tuesday, February 4, 2020
5. Membranous labyrinth
In bony labyrinth
Filled with endolymph.
Surrounded by perilymph.
Consists of
Utricle & saccule – in bony
vestibule
Semicircular ducts – in
canals
Ducts of cochlea – in
cochlea
Tuesday, February 4, 2020
7. Semicircular canals
Anterior
Posterior
Lateral
One end of each dilated
– ampulla which
contains receptor organ
– crista ampullaris.
They open into utricle
by 5 orifices.
Tuesday, February 4, 2020
8. Otolith organs
Utricle & saccules
together called – otolith
organs.
Utricle – larger, opens 3
semicircular canals
Connected to saccules &
endolymphatic sac
Saccules
Connected to utricle &
cochlea – ductus reunion.
Tuesday, February 4, 2020
9. Vestibular receptors
Hair cells
Location – of
semicircular canals in
mass of tissue within
ampulla- crista
ampullaris.
Of otolith organs in
macula.
Tuesday, February 4, 2020
15. Receptors in otolith organs
macula
Structure
Neuroepithelium
Supporting cells
Otolith membrane.
Contains crystals of Ca
carbonate – otoliths or
otogonia
Tuesday, February 4, 2020
16. Stimulation of receptors in
otolith organs.
Macula of utricle
Linear acceleration.
Macula of saccule
Vertical acceleration.
Tuesday, February 4, 2020
17. Vestibular pathways
First order neurons
Vestibular nuclei
Afferents
Efferents
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20. Mechanism of functioning
Mechanism of
stimulation –
At the beginning of
movements
At the end of
movements.
Mechanism of
adaptation. – after 15-
20 sec of continuous
movement.
Tuesday, February 4, 2020
21. Functions
Utricle –
Stimulated during
horizontal acceleration
Saccules –
Stimulated during
vertical acceleration
Tuesday, February 4, 2020