Overview of Vestibular System Components

The Vestibular System

• Detects changes in the motion and position of the head (which may or may not correspond to changes in the
motion and position of the body)
• Located in the inner ear




• Three semi-circular ducts inside the bony semi-circular canals, ending in an enlarged chamber, ampulla
• Two associated but separate sack-like swellings:
1. Utricle
2. Saccule




1. MACULA
• Perceives tilt/angle in relation to the gravitational field

2. CRISTA
• Perceives acceleration/deceleration




• In the utricle and saccule (not connected to the semi-circular canals)
• Each macula contains hair cells covered by a gelatinous otolith membrane containing
small CaCo3 crystals, otoliths
• The action of the gravitational field on the otoliths triggers a response from the
hair cells below




• In the ampulla, the swollen base of the semi-circular canals
• The semi-circular canals are located in three different angles
• Acceleration/deceleration of the head causes movement of the liquid in the
semi-circular canals
• This movement shifts the jelly-like cupula an triggers a response from the
sensory hairs in the crista




Integration of Physiological Systems Page 1