Excitability of lower limb myotatic reflex arcs under the influence of caloric labyrinthine stimulation. Analysis of the postural effects in man.

The excitability changes of myotatic reflex arcs have been investigated in 36 volunteers by two methods (tendon reflex and tonic vibration reflex) in a bilateral invertigation of soleus, quadriceps, biceps femoris, and tibialis anterior after caloric stimulation of the labyrinth. The extensor myotatic reflexes are facilated during the irrigation and the nystagmus phases. Contrary to the soleus, quadriceps facilitation is not symmetrical during the phase of nystagmus but predominates on the side opposite to the expected axial deviation. The short biceps femoris reflexes are slightly facilitated. The postural modifications arise from differences in the degree of bilateral facilitation of the extensors.