Table 2. The physiological functions responsible for changing the attributes of the angular movement.

Angular movement	MN activity	Muscle recruitment
amplitude	fast	fast
average position	slow (+fast)	slow (+fast)
frequency	CPG

Fast and slow relate to fast and slow muscle fibres or motoneurons (MNs), respectively. (+fast) means that additional activity of the fast muscle fibres (or MNs) substantially contributes to producing the average position of the protractor-retractor angle during oscillation.