Elements of human physiology (1907) Elements of human physiology elementsofhumanp05star Year: 1907 610 PHYSIOLOGY and indicates a heightened reflex excitabihty of the lower spinal centres, perhaps reinforced hy impulses from the cere- bellum. The value of the tendon phenomena as a means of dia- gnosis has tended to obscure their great importance in the normal individual. Every joint is protected by inextensible ligaments and by muscles. A sudden strain on a ligament either will have no effect, or will rupture some of its fibres and perhaps injure the adjacent joint surfaces. An ordinary Fig.
Elements of human physiology (1907) Elements of human physiology elementsofhumanp05star Year: 1907 610 PHYSIOLOGY and indicates a heightened reflex excitabihty of the lower spinal centres, perhaps reinforced hy impulses from the cere- bellum. The value of the tendon phenomena as a means of dia- gnosis has tended to obscure their great importance in the normal individual. Every joint is protected by inextensible ligaments and by muscles. A sudden strain on a ligament either will have no effect, or will rupture some of its fibres and perhaps injure the adjacent joint surfaces. An ordinary Fig. 278. Ant? crur .n. Diagram to show muscles and nervei3 concerned in Sherrington's experiment on tlie reciprocal innervation of antagonistic muscles. , , , third, fourth, and fifth lumbar roots; , S.'2, first and second sacral roots. reflex contraction would be powerless to prevent this, since the mischief would be done before the reaction could take place. But the central nervous system confines itself to keeping the muscles awake, so that they themselves may react to any sudden increase in their tension by an equally sudden contraction, which saves the joint before the central nervous system has even become aware of the strain. Co-ordmation of Movements hy the Cord.—Since the act of stretching a muscle in a normal state of tone acts as an excitant, and causes increased tone or even contraction, every
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