Posture

State of the body consisting of the maintenance of relationships between body parts (body-referenced definition based on an egocentric coordinate system definition), relationships between body and environment (environmental-reference based on an exocentric coordinate system), and with reference to the gravitational vector or field (another environmental-referenced definition, but based on a geocentric coordinate system).  Posture has three functions involving maintenance of: 1. stability in the face of gravity (i.e., an anti-gravity response); 2. stability in the face of externally-induced change (e.g., after a shoulder push when sitting or standing), which functions by means of feedback control; 3. stability in the face of self-induced change (e.g., when reaching for an object), which requires anticipation or feedforward control (see figure below).

The components of postural control. 

See Asymmetrical tonic posture or response (ATNR), Centre of gravity, Centre of mass, Crying, Feedback, Feedforward, Gross motor abilities, Hyperextension, Movement, Postural control