Question

What are somatic and autonomic nervous system and how do they send signals to which muscles

Answer 1

The Somatic Nervous System is the part of the peripheral nervous system that handles voluntary control of body movements. ... The Autonomic Nervous System is the part of the peripheral nervous system that acts as an involuntary control system b(elow the level of consciousness), and controls visceral functions.

In somatic nervous system
In the process of voluntary movement, sensory neurons carry impulses to the brain and the spinal cord. After processing, a signal is sent back to the skeletal muscles, organs, and skin by way of the somatic motor neurons. The second function of the somatic nervous system is the process of the reflex arc.

In autonomic nervous system The autonomic nervous system (ANS) is still controlled by the brain too -- but is not conscious. The brain's hypothalamus is required to send signals to the heart, your glands, breathing, digestion etc.