The vestibular system at a glance — what it does, its five sensory organs, and the pathway from inner ear to brain that keeps balance, gaze, and spatial orientation stable.
What the vestibular system does
The vestibular system is the body's sense of balance and head movement. It continuously monitors the position and motion of the head, and uses that information to keep posture stable and vision steady while we move.2
Five sensory organs
Each inner ear holds the peripheral vestibular apparatus — the labyrinth — which contains five sensory organs: three semicircular canals and two otolith organs, the utricle and the saccule.3
The five organs divide the work of sensing head motion:3,8
Three semicircular canals — sense rotation (angular acceleration)
The utricle — senses horizontal linear acceleration and tilt
The saccule — senses vertical linear acceleration
Labyrinth
The peripheral vestibular apparatus housed within the temporal bone of each ear — the three semicircular canals and the two otolith organs, together with the fluid and hair cells inside.
From inner ear to brain
Signals from the five organs travel along the vestibular nerve — a branch of cranial nerve VIII — to the vestibular nuclei in the brainstem.3
When the system fails
Because the system spans the inner ear, the nerve, the brainstem, and the cerebellum, dysfunction anywhere along it can cause vertigo, imbalance, and nystagmus — the involuntary eye movements that often signal a vestibular problem.62