Question

When you consciously decide to move a finger, where do action potentials specifically arise and how are they transmitted to the brainstem and then the spinal cord.

Answer 1

• Movement occurs due to muscle contraction.Spinal motor neurons are continously influenced by the impulses arriving from various supraspinal centers via descending fibers.These influences originate in brainstem,cortex,cerebellum and basal ganglia.
• The command is conveyed to the spinal cord motor neurons from the cortex directly via corticospinal tract,and from basal ganglia and cortex via corticobulbar pathways and from cerebellum via its projection to the brainstem nuclei.
• The supraspinal inputs controlling the spinal motor neurons carryout three functions

1. Initiation and execution of voluntary activities.
2. coordination and smoothening of movements
3. postural adjustments to provide a stable background for movement