Notes on Vestibular System

Overview

• Vestibular System: A sensory system providing the brain with information on motion, head position, and spatial orientation.
• Functions:
  • Maintains balance.
  • Stabilizes head and body during movement.
  • Maintains posture.

Main Components

• Location: Inner ear, within the vestibular labyrinth.
• Connection: Continuous with the cochlea.

Semicircular Canals

• Structure: Three tubes, each reflecting a plane of head rotation.
• Movements Detected:
  • Nodding up and down.
  • Shaking side to side.
  • Tilting left and right.
• Fluid: Endolymph fills these canals.
• Mechanism:
  • Head rotation moves endolymph in the corresponding canal.
  • Endolymph flows into the ampulla.
  • Hair Cells: Sensory receptors located in the ampulla.
    • Stereocilia: Small hair-like structures at the top of hair cells.
    • Movement of stereocilia leads to neurotransmitter release.
    • Sends motion information to the brain.

Otolith Organs

• Purpose: Detect forward/backward movements and gravitational forces.
• Types:
  • Utricle: Detects horizontal plane movements.
  • Saccule: Detects vertical plane movements.
• Mechanism:
  • Hair cells detect movement via shifting otoconia (calcium carbonate crystals).
  • Movement leads to displacement of hair cells, sending information to the brain.