What part of the nervous system sends signals to the muscles that are voluntarily controlled?
The nervous system can be divided into two main parts:
- Central nervous system (CNS) - brain and spinal cord
- Peripheral nervous system (PNS) - contains motor neurons and sensory neurons outside of the CNS
The motor neurons of the PNS are efferent (sending signals from the CNS to the body) and can be divided into:
Somatic - controls VOLUNTARY movement
Ex: flexing your arm, nodding your head, etc.
Autonomic - controls INVOLUNTARY actions
Ex: increasing/decreasing your heart rate, contracting/dilating your pupils
Note: the autonomic nervous system can be further categorized by the sympathetic and parasympathetic divisions, which typically have opposite effects on the same targets (Ex: pupil constriction is a parasympathetic activity, pupil dilation is a sympathetic activity)