Now, when they exit the spinal cord, motor neurons exit from the front side of the spinal cord and the front side is also known as the ventral side. So if this is the cross sectional area of the spinal cord then this is the front side, it's the ventral side and this is where the motor neuron will leave. So let's move on to the sensory neuron. So what exactly is a sensory neuron? A sensory neuron is basically the neuron that begins at some receptor. It receives a signal from the environment and then it sends that signal into the central nervous system.