BIOLOGICAL SIGNIFICANCE OF HEAD POSTURE

1showed that head posture not only undergoes passive alterations but can, under certain circumstances, effect an active influence. He revealed in his experiments on animals that turning of the head to one side caused extension of the "facial" limbs and flexion of the "occipital" limbs. Tonic neck reflexes were later observed, as is well known, under pathological conditions in human beings too. They appear with certain variations, particularly in diffuse cerebral disorders of traumatic or inflammatory origin, as well as in tumors of the brain, in children and in adults alike. The discovery of the tonic neck reflexes disclosed, first, the existence of an extended motor relationship among the separate members of the body. It revealed further the important fact that head posture influences the tone and position of the extremities, as is apparent under pathological conditions, but is certainly effective under normal conditions too. After the general acceptance of these conclusions further scientific interest in the significance of head posture seemed to have exhausted itself for several decades. The interesting investigations which Goldstein * carried out later on the tendency to optimal behavior, wherein the problem of head posture is dealt with too, seem not to have received adequate consideration. Clinical experiences gained recently from further observations may, however, show very well the significance of head posture from the biological point of view. These experiences concerned especially patients with systematized unilateral disturbances of equilibrium. I. POSTURE OF THE HEAD IN UNILATERAL DISEQUILIBRIUM The posture of the head in unilateral disequilibrium assumes a special interest. In some patients with this condition the spontaneous posture of the head does not alter visibly. In those patients, however, in whom unilateral disequilibrium consti