Final answer:
Body movement is controlled by the nervous system, particularly the somatic nervous system for skeletal muscles, involving both voluntary and involuntary muscle activities regulated by motor units.
Step-by-step explanation:
All movement in the body is controlled by the nervous system, more specifically by the somatic nervous system when it comes to skeletal muscles. The somatic nervous system enables voluntary control over these muscles. However, the role of the nervous system in muscle movement doesn't just end there; it extends to the regulation of all three types of muscle tissue. For example, cardiac muscle contracts during an increase in heart rate when exercising, and smooth muscle helps in moving food through the digestive tract.
Furthermore, the responsiveness of muscles, including actions like withdrawing a hand from a hot surface, is due to neural responses from sensory stimuli. This broad capability also encompasses involuntary muscle activities, such as breathing, which can be controlled without conscious effort. The muscular system, inclusive of functions like contraction and muscle tone, operates under the intricate regulation of neural control facilitated by motor units.