Chapter-2: The Mechanism of Postural Control


 The mechanism of postural control

As we all know muscles of the body play a major role in attaining both dynamic and static postures but, there is a contribution of some other body systems working simultaneously in co-ordination with the muscles. There is a center governing the simultaneously working systems of the body. Let us discuss all the important elements of postural control and their mechanism.

1.            The governing system of nervous control:
The maintenance and adaptation of a posture is controlled by the system of nervous control. The system works on a give and take mechanism of receptor organs (eyes, ears, muscles and joints) giving the afferent stimuli and effector organs (muscles) receiving the command to perform the actions. All that is required for a brain to change a position is an input to produce an output. The input can either be environmental (push, pull, jerk, hit etc.) or internal (brain’s own will to adapt or change a position). The nervous system involves sub-systems working for it.

a.            Sensory system:
Vestibular system: the system is responsible for equilibrium, motion and orientation. The system plays a vital role in posture as it provides a sense of balance and control. The vestibular system governs the actions of eyes and positions of head. The semicircular canals of the ears consists of fluid which moves along with movement of head.

b.            Proprioception:
The proprioception provides a sense of position and movement. The receptors are spread throughout the body in muscles, joints, ligaments and tendons.

c.  Vision:
    The eyes help in analyzing a person’s body position. Where we stand and which direction should we move in is all determined by the visual receptors. Vision also plays an important role in identification of the surface type (smooth, slippery, rough, bumps, inclinations etc.)


2.            Central nervous system:
The afferent signals are sent to brain and an efferent response is generated. The brain analyzes the current need of the body to either attain or change a posture and responds accordingly.

3.            Muscular system:
The muscular system acts as a major component of postural control by contracting a number of muscles simultaneously in both static and dynamic postures. Which muscles are to be contracted depends on the type of position and might differ in each position. Which muscle has to work also depends on the motion of the body, base of support (BoS) and center of mass (CoM). The base of support and center of mass changes accordingly to provide stability and fall prevention in different body positions (standing erect, standing on one leg, standing on stairs, standing in a moving vehicle).

4.            Joint structures:
Weight bearing joints of the body plays an important role in maintaining balance in weight bearing positions. The joint receptors send the afferent signals in order to approximate the joint and attain stability.



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