Rigor

Rigor is a medical term for muscle rigidity. It is caused by an increase in muscle tone with simultaneous, centrally controlled activation of muscles and their counterparts. Affected persons feel a stiffness with partial pulling discomfort. All living muscles have a certain basic tension, the so-called resting tone. This is controlled and regulated by the CNS. Both the pyramidal and above all the extrapyramidal motor system play a role here. The rigor arises as a functional disturbance of the extrapyramidal motor system whose core areas are located in the midbrain.