Sensory system

• Weighting of sensory inputs are context specific - Healthy individual, In a well lit environment, Firm base of support:

  • Vestibular - 20%
  • Vision - 10%
  • Somatosensory - 70%
• Input 1: vestibular:

  • we are not examined on this, but need to know its part of our overall mechanism to stay upright against gravity
• Input 2: Vision:

  • Tells us about our environment, see obstacles (pro-active ‘balance’ reaction)
  • Help form motor memories (cognitive spatial maps) i.e. know your way around in the dark in familiar places
  • Tells you a shiny floor may be slippery & adjust movement (predictive – based on prior experience)
• Input 3: Somatosensory:

  • Proprioceptors (“Perceiving one’s own self”)
  • Located in:
  • Muscle spindle - signal static and dynamic changes in muscle length
  • Golgi tendon organ - sensitive to tension changes
  • Joint receptors (several in joint capsule) - trigger at extreme lengths
• Input 3: Somatosensory:

  • cutaneous receptors
  • mechanoreceptors - detect mechanical stimuli
  • thermoreceptors - detect temperature changes
  • nociceptors - detect damage to skin