Reflexes and Muscle Tone

Abstract

The spinal cord contains the local neuronal circuits that coordinate somatic reflexes. These circuits are participants in the complex voluntary movements of the body that are governed by the higher centers of the brain. One expression of somatic motor function is the effortless ease with which humans carry out the most dexterous of motor activities without a conscious awareness of joint movements and the accompanying muscle contractions synchronized with the required “relaxing” of antagonistic muscles. The quality of sequential combinations of movements is dependent on the continuous flow of visual, somatosensory, and postural (vestibular and joint senses) information that results in seemingly immediate integrated responsive actions. Although we might be consciously aware of making decisions regarding execution of the movements to accomplish the goal, we are unaware of the details that are instrumental in creating the motions, as they seem to take place automatically.