Maculae

The vestibule is a region of the inner ear which contains the saccule and the utricle, each of which contain a macula to detect linear acceleration.

The macula of saccule lies in a nearly vertical position. Its function is to detect vertical linear acceleration. It is a 2 mm by 3mm patch of hair cells. Each hair cell of the macula contains 40 to 70 stereocilia and one true cilia, called a kinocilium. A gelatinous cover called the otolithic membrane envelops the tips of the stereocilia and kinocilium. The otolithic membrane is weighted with small densely packed protein-calcium carbonate granules called statoconica.

The macula of the utricle is in a horizontal position and detects horizontal acceleration. The coordinated sensory perception of acceleration both vertically and horizontally along the vestibular nerve, allow for the perception of linear acceleration in any direction.