Renshaw cells are inhibitory interneurons found in the spinal cord. They synapse on the alpha motor neuron and limit its activity in order to prevent muscle damage. These alpha motor neuron send signals to muscles.
It is difficult to evaluate spasticity in smaller muscles especially those that cross various joints. Hence clinical observation and evaluation is used. In addition to this, electromyography and diagnostic blocks with local anesthetics are also used. A modified barium swallow or video-fluoroscopic evaluation can help in characterizing severity of dysphagia and also in identifying aspiration.