Functions of the spinal cord

1. Conduction pathway
   • Carries sensory impulses from skin, muscles, joints, and viscera to the brain through ascending tracts.
   • Carries motor commands from the brain to skeletal muscles through descending tracts.
2. Reflex center
   • Produces rapid, automatic responses without requiring conscious brain input first.
   • Examples: knee-jerk (stretch) reflex, withdrawal of a hand from a hot object, and tendon reflexes.
   • A reflex arc involves a receptor, sensory neuron, spinal interneuron(s), motor neuron, and effector muscle. Costanzo Physiology, 7th ed., p. 110.
3. Integration of motor activity
   • Spinal interneurons integrate sensory feedback with descending commands from the brain.
   • They regulate muscle tone, coordinate agonist-antagonist muscle activity, and help maintain posture.
4. Locomotion
   • Contains neural circuits called central pattern generators that help create rhythmic movements such as walking.
   • The brain initiates and modifies walking, while sensory feedback adjusts it to terrain and balance demands.
5. Autonomic control
   • Contains sympathetic outflow from T1-L2 and parasympathetic outflow from S2-S4.
   • Participates in control of blood vessels, sweating, bladder emptying, bowel function, and sexual function.
6. Protection and local processing
   • Allows important protective reactions, especially pain-related withdrawal, to occur quickly at the spinal level.
   • It can process and modulate incoming sensory signals before they reach higher brain centers.