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Which structures are included in the peripheral nervous system?

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Diagram of a human figure showing the full nervous system, including the brain, spinal cord, and branching peripheral nerves throughout the body, with labels for each part. — human nervous system The conduction of electrochemical stimuli from sensory receptors in the human nervous system occurs via organized groups of specialized cells, consisting largely of neurons, various neural support cells, and tracts of nerve fibers.

The peripheral nervous system (PNS) serves as the communication network relaying sensory and motor impulses between the central nervous system and the rest of the body, including the skin, skeletal muscles, and internal organs. It consists of the following primary structures:12

Spinal nerves: These mixed nerves contain both sensory and motor fibers, facilitating communication between the spinal cord and the body.13
Cranial nerves: These 12 pairs of nerves emerge from the brain and are primarily responsible for sensory and motor functions related to the head and neck, as well as certain visceral functions.415
Autonomic nervous system: Certain parts of this system, which regulates involuntary bodily processes, are included in the PNS. This includes autonomic ganglia—clusters of nerve cell bodies located outside the central nervous system—and the associated nerve fibers that innervate cardiac muscle, smooth muscle, and glands.16

Collectively, these structures are composed of neurons and synapses, with nerve cell bodies often organized into clusters known as ganglia.1