KEY CONCEPTS:

• This very schematic diagram illustrates the descending motor influences from the brainstem on spinal motor neurons, especially those of the cervical cord.
• These centres are involved in the maintenance of an upright posture, adjustment of muscle tone and regulation of spinal reflexes via excitatory and inhibitory synapses.
• They work cooperatively with other motor pathways to adjust and steer voluntary movements, and are influenced by descending connections from the cerebral cortex, limbic system and other brain centres.