Fill in the blank with a wording the parenthesis When the knee is hit with a rubber hammer, the leg kicks forward, and then returns to the original position. This is an example of a spinal reflex arc. The sensation of the hammer travels to the (eyes, leg, spinal cord, brain) , where it activates motor neurons that cause the leg to move. This reflex is part of the (somatic, sympathetic, autonomatic) nervous system.