control of posture 2

Question 1

Motor outputs in the postural control system include:

Answer 1

voluntary > Anticipatory > Automatic > Reflex

Question 2

voluntary motor outputs

Answer 2

• cortically driven
• Self-generated or in response to an external stimuli
• 200+ milliseconds from initiation of signal in the cortex
• Purposeful activities
• Complex and coordinated with infinite variety
• Output via the corticospinal and corticobulbar tracts

Question 3

anticipatory motor outputs

Answer 3

forward) in anticipation of the destabilising forces caused by the movement Cortically driven (part of the movement plan)
Memory-based/learnt movements, can adapt with repetition and change in

Question 4

anticipatory motor outputs 2

Answer 4

• Preparation
  Eg activity in leg
  muscles before movement of arm
  Can adapt with a change in circumstances – anticipation of local pain

Question 5

Ankle strategy - automatic

Answer 5

Used when perturbation is: Slow
Low amplitude
Contact surface firm, wide and longer than foot
Muscles recruited distal-to- proximal
Head movements in-phase with hips

Question 6

Hip strategy - automatic

Answer 6

Hip strategy

• Used when perturbation is fast or large amplitude
• Surface is unstable, narrow or shorter than feet
• Rapid trunk adjustments to larger amplitude perturbation
• Muscles recruited proximal-to- distal
• Head movement out-of-phase with hips

Question 7

step strategy - automatic

Answer 7

• Used to prevent falls
• When perturbations are fast or large amplitude
• When other strategies fail
  Alters base of support
  Requires the recruitment of many muscles

Question 8

pertubations

Answer 8

First attempt: Stepping strategy
Quick modification of response needed
Second attempt: Hip strategy

less visual stimulus, stimulus in is difference with risk of damage different
when comparing going backwards vs fwds

Question 9

Reflex motor outputs

Answer 9

• Simplest neural circuit involves a sensory receptor and its afferent axon and a group of motor units the receive information in the spinal cord
• Postural control is modified directly at the spinal cord by pain, voluntary contraction, other sensory inputs etc

Question 10

reflex

Answer 10

• Controlled at the spinal cord, triggered by external stimuli
• Occur with a latency of ~35 to 40 Milliseconds
• Regulate local muscle contraction only (not generalised, multi-segmental) - Highly Stereotypical