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PNS — Audia / Aurora Glass

Peripheral Nervous System (PNS)

The peripheral nervous system (PNS) lies outside the brain and spinal cord and serves as the communication network between the CNS and the rest of the body (limbs, organs, sensory structures).

CNS and PNS overview
CNS vs PNS overview.

Core Functions of the PNS

Two primary roles:

  • Sensory Input (Afferent): Transmits data from sensory receptors to the CNS.
  • Motor Output (Efferent): Sends commands from the CNS to effectors (muscles, glands).

This bidirectional flow supports interpretation of stimuli (pain, temperature, proprioception) and appropriate responses (muscle contraction, gland secretion).

Divisions of the PNS

1) Somatic Nervous System (SNS)

  • Controls voluntary movement and carries conscious sensory input.
  • Includes motor neurons to skeletal muscle and sensory neurons from skin, muscle, joints.

2) Autonomic Nervous System (ANS)

  • Regulates involuntary functions (heart rate, digestion, respiratory rate).
  • Subdivisions:
    • Sympathetic: “Fight or flight”.
    • Parasympathetic: “Rest and digest”.
    • Enteric: Intrinsic GI control.
Somatic vs Autonomic comparison
Somatic vs Autonomic — high-level comparison.