Stimulation of this motor cell results in an impulse that travels along it's axon through the Ventral Root to the spinal nerve, where it reaches the muscle and causes it to contract . Contraction of the muscle straightens the leg. This reflex, like most, is protective in nature. Protection against sudden and possibly injurious movements at a joint is afforded without conscious thought. If the sensory stimulus had to reach the brain and travel from the brain down the spinal cord before corrective action could be taken, the result of such delay might be disastrous.
Voluntary movement is the result of the constriction of striated muscle.
There is another motor system with a slightly different anatomical pattern that controls the functions of structures not under voluntary control. This is the Autonomic Nervous System . The autonomic system is subdivided into two systems that produce two different types of Physiological Responses . The Sympathetic and the Parasympathetic systems. The Sympathetic system consists of paired neurons that arise from all the Thoracic and the first two Lumbar Spinal cord segments.