Now let's take a look at the maculae
that are found in the saccule and the utricle.
The maculae contain hair cells
and associated here on their apical region
are some structures that we refer to as otoconia.
These overly the haircells that are shown down in through here.
The otoconia are three times denser than the surrounding endolymph.
Changes in head position,
for example tilting or linear acceleration
causes displacement of the otoconia and
depolarization or stimulation of the hair cells.
This will then initiates synaptic transmission of the
afferent nerve fibers of the vestibular component
of cranial nerve number VIII, the vestibulocochlear nerve.
We also have hair cells in the semicircular canals.
These are associated with the cristae ampullaris.
The cristae ampullaris is characterized by the cupula,
very prominent body associated with the cristae ampullaris.
Here are the hair cells, and in the simplified drawing,
you see one hairlike extension are the sensory hair cells.
In reality, there will be numerous cilia
which define these hairlike extensions of the apparatus.
What will happen here with angular accelaration is
let's say you're moving to the right,
you're rotating, you're pivoting,
what will happen is the endolymph has greater inertia
than there's the cupula, and so the endolymph here
will push the cupula in this direction
causing bending of the haircells and depolarization along the
afferent nerve fibers associated with the vestibular nerve.
And so this will result in synaptic transmission
of those afferent nerve fibers.