On the nature of postural reflexes

Abstract

The “reflex standing” seen characteristically in the spinal animal, and exaggerated in the decerebrate animal, when analysed myographically is found to be a reflex contraction which is caused by stretch of the muscle itself, the “ stretch reflex ” (31). In upright postures gravity provides the stretch which elicits the reflex, and the resulting antigravity stretch response is prominent in all limb extensors. This response is a typical extensor reflex and is found only in fractional form in the flexors (5) in the cat, dog, and other quadrupedal mammals. In such animals as the sloth where the typical postures involve stretch of flexor muscles, decerebrate rigidity involves the flexors (46).