Voluntary vs Automatic responses in the Somatic Nervous System.

This question is about the somatic nervous system (SNS).

I read that this the SNS part of the peripheral nervous system (PNS) and that it controls skeletal muscle. It is therefore thought to be voluntary. In contrast, the autonomic nervous system controls smooth muscle, under involuntary control.

What I'm wondering is if reflex arcs (or reflexes) are controlled by the autonomic nervous system, why is it making use of skeletal muscle?

Take the example of the reaction of moving your hand away when it is placed on something hot. These motor commands come from the autonomic nervous system but control the arm muscles that are normally controlled consciously. In other words things normally controlled voluntarily.

The response was activated by the ANS, and was therefore automatic, but the muscles supplied by these motor commands were skeletal muscles? Can someone explain this (contradition) or perhaps correct my wrong thinking?

Authored By Alex Catley on Wednesday 3rd October 2012


Michael Hassall
Medical Student
Posted about 7 years ago

The reflex arc does not involve autonomic nerves. The arc works by:

  • Transferring the action potential from the somatic sensory nerve directly onto the somatic motor nerve without sending signals to the brain.
  • The action potentia