In a series of previous studies1 I have formulated a conception of the efferent nervous system, founded on the existence, as I believe, of dual pathways subserving respectively the functions of motion and posture. According to this theory, the kinetic mechanism consists of a series of systems which are concerned with the production of movement, while the static mechanism represents a coextensive series of neural systems which are concerned with the maintenance of posture. All of the complicated phenomena of motility are dependent on these twin mechanisms, which function together in harmony.
In accord with this duality of function, striated muscle fiber is composed of two distinct substances, one subserving a contractile, the other a postural function. The sarcostyle is the contractile portion of the muscle fiber and represents the myokinetic mechanism; the sarcoplasm is the postural constituent and represents the myostatic mechanism.
In disorders of motility, as in
HUNT JR. PSYCHIC REPRESENTATIONS OF MOVEMENT AND POSTURETHEIR RELATION TO SYMPTOMATOLOGY. Arch NeurPsych. 1925;14(1):7-19. doi:10.1001/archneurpsyc.1925.02200130010002