The human body has 8 sensory systems which give us information about the environment and our place within the environment.
The 5 most commonly known sensory systems include:
- Tactile – the sense of touch
- Visual – the sense of sight
- Auditory – the sense of hearing
- Gustatory – the sense of taste
- Olfactory – the sense of smell
The 3 less commonly known sensory systems include:
- Vestibular – the sense of our head position in space
- Proprioception – the sense of knowing where our body is in space, this information comes from our muscles, joints, tendons and ligaments
- Interoception – the sense of the physiological condition of the body (hunger, thirst, pain, temperature, the need to go to the bathroom, etc.)
Today we are going to talk more about the vestibular system. The vestibular receptors are located in our inner ear. The receptors include the 3 semicircular canals (anterior, lateral and posterior) and the otoliths (utricle and saccule). The semicircular canals pick up rotary movement and the otoliths pick up linear movement.
The vestibular system answers 2 basic life questions:
- Which way is up?
- Where am I going?
Any movement of the head in any direction (up and down, forward and back, side to side, diagonal and rotary) activates the vestibular system. 25% of the vestibular information received goes directly to the cerebellum which is responsible for balance and posture. The other 75% of vestibular information goes to the brainstem via the vestibular nuclei which then connects to many other parts of the brain including:
- Reticular formation – arousal, orientation, regulation & attention
- Spinal cord – postural alignment and control
- Oculomotor nuclei – head orientation & stability for oculomotor (eye) control
- Autonomic centers – gravitational impact on cardiovascular, visceral & respiratory control
- Cerebral cortex – spatial orientation & body movement
Since the vestibular system has so many connections in the brain it is very important that the vestibular system is functioning well. In many of the children that we see in Occupational Therapy their vestibular systems are not functioning optimally. Many children have an under-responsive system or an over-responsive system. A child with an under-responsive system may be able to spin for hours without getting dizzy or sick. A child with an over-responsive system may get dizzy or sick with even the slightest movement.
In Occupational Therapy one of the goals is to help the vestibular system work optimally so that sensory information is processed correctly in the brain to allow the eyes to work well, the ears to work well as well as the many other areas that have been discussed above.
References: From Eyesight to Insight: Visual & Vestibular Assessment & Treatment