Equilibrium and Postural Control

Sensory system

Vision

• Perceive movement; orient body in space

Vestibular

• Info on postural control and balance; semicircular canals detect angular acceleration/deceleration forces affecting the head; otolith organs detect linear acceleration and responds to gravity; helps orient the head

Somatosensory

• Detects pressure sensation that is in contact with the support surface (involves muscles and joints)

Components of the postural control system

Limits of stability

Sensory organization

Eye head stabilization

Musculoskeletal system

Motor coordination

Predictive central set

Environmental adaptation

Sequence of development of postural control

Righting reactions

Protective reactions

Equilibrium reactions

Nashner’s model of postural control in standing

Ankle strategy

• Need a solid surface in contact with feet

Hip strategy

Stepping strategy

• Depends on speed and strength of the disturbance

Age-related changes in coordinated movement

Decreased strength

Slowed reaction time

Decreased ROM

Postural changes

Impaired balance

Age-related changes in postural and motor control

Balance strategies in sitting

• Trunk muscle activation

• Anticipatory control of posture occurs before voluntary movement by 9mo old

• Anticipatory control of posture increases as children get older

Balance strategies in standing

• Older adults have more spontaneous sway than younger people

• Possibly due to effects of gravity or to get more sensory info for postural control

• If eyes closed, older adults stand more asymmetrical

Postural sway

Normal

Parkinson’s

Ataxia