REFLEXNÍ OVLIVNĚNÍ SVALOVÉHO NAPĚTÍ PROPRIOCEPTIVNÍM VSTUPEM - TEORETICKÁ VÝCHODISKA Reflex affecting of muscle tone by proprioreceptive input - theoretical starting points

Summary The work presented here offers an analysis of the literature dealing with the rigidity and tone of skeletal muscles, spasticity and mechanoreceptors in the locomotor apparatus, nerve reflexes associated with the muscle tone control and topographic and directional specificity between the skin and intensity of the stretching reflex and H+reflex of skeletal muscles. The purpose of the search for the literature is to provide a scientific basis for a derivation of hypotheses for dissertation theses, the scope of which is the effect of the skin receptor stimulation on the muscle tone in selected muscles in healthy individuals and in patients with central motoneuron syndrome. The analysis of the literature demonstrated that the muscle tone has its passive (EMG silent) and active (EMG active) components. The passive component is given by viscoelastic characteristics of muscle tissues, i.e. of muscle fibres and interstitial connective tissue. The research indicates that the connective tissue also contains contractile cells, thus being also capable of active contractions. The active component is given by nervous reflexes, which are induced by a muscle extension: by the stretching segmental reflex and transcortical reflex. These reflexes are active in enhanced requirements for the joint stabilization. The spasticity can be defined as a disorder of the sensomotor system characterized by an increase in the muscle tone depending on the rate of the extension. The spasticity is one of components of central motoneuron syndrome together with an attenuation of flexor reflexes, muscle weakness and loss of the skill. An important role in this process belongs to changes in the activation of the stretching reflex due to the hyperexcitability of alpha motoneurons and reduction in the inhibition by descendent motor ways. Studies of proprioreceptors can be divided into morphological and electrophysiological ones. In terms of the function, the evaluation is of importance, according to which it is possible to differentiate one from another receptors with slow adaptation (static) detecting the joint situation and receptors with a rapid adaptation (dynamic) detecting the joint movement. The results of this study justify the following formulation of principal hypotheses for our work: 1) we can expect that irritation of skin receptors induces statistically significant changes in the tension of selected muscles and 2) we can expect the specificity between directions of the skin tension and facilitation or inhibition of the muscle tone. The analysis of the literature also significantly contributed to the formation of a homogeneous experimental group, particularly due to conclusions indicating that one group cannot simultaneously include patients with CMP and transversal medullar lesion since in terms of neurophysiology, these are no identical pathological conditions. A finding is also of importance that an increase in the passive muscle rigidity by connective tissue contractures or muscle fibrosis negatively affects the reflex action on skeletal muscles.