The density of muscle spindles in the medial, intermediate and lateral columns of human intrinsic postvertebral muscles

Abstract

Studies of the mechanics of the trunk have reported that during the initial phase of lifting in the stooped position the body uses additional support of intratruncal pressure to limit the work done by the erector spinae muscle (Davis, 1956; Bartelink, 1957). These workers showed that intrathoracic and intra-abdominal pressures varied proportionately with the work done. Kumar & Davis (1973) observed that variations in intra-abdominal pressures closely correlated with electrical activity in the postvertebral as well as the anterior abdominal wall muscles. They suggested that receptors in the erector spinae muscles might be implicated, but they did not specify which components of the muscle were involved.