- A state of increased tone of a muscle (and an increase in the deep tendon reflexes). For example, with spasticity of the legs (spastic paraplegia) there is an increase in tone of the leg muscles so they feel tight and rigid and the knee jerk reflex is exaggerated.
* * *One type of increase in muscle tone at rest; characterized by increased resistance to passive stretch, velocity dependent and asymmetric about joints ( i.e., greater in the flexor muscles at the elbow and the extensor muscles at the knee). Exaggerated deep tendon reflexes and clonus are additional manifestations. SEE ALSO: clasp-knife s..- clasp-knife s. initial increased resistance to stretch of the extensor muscles of a joint that give way rather suddenly allowing the joint then to be easily flexed; the rigidity is due to an exaggeration of the stretch reflex. SEE ALSO: lengthening reaction. SYN: clasp-knife effect, clasp-knife rigidity.
* * *spas·ti·ci·ty spa-'stis-ət-ē n, pl -ties a spastic state or condition esp muscular hypertonicity with increased tendon reflexes
* * *n.resistance to the passive movement of a limb that is maximal at the beginning of the movement and gives way as more pressure is applied. It is a symptom of damage to the pyramidal system in the brain or spinal cord. It is usually accompanied by weakness in the affected limb (see spastic paralysis). Compare rigidity.
* * *spas·tic·i·ty (spas-tisґĭ-te) the state of being spastic; see spastic (def. 2).
Medical dictionary. 2011.