04. Motor Systems Anatomy

• pyramidal tracts start in the cortex and decussate in the medulla

  • corticospinal
  • corticobulbar
• extrapyramidal tracts start in brainstem and don't pass through pyramids

  • reticulospinal
  • rubrospinal
  • tectospinal
  • vestibulospinal
• if upper motor neurone synapses in brain stem the lower is a cranial nerve, if it synapses in the spinal cord it is a spinal nerve
• precentral gyrus = primary motor cortex, anterior to central sulcus
• premotor cortex = planning of movement, then goes to primary motor cortex
• corticospinal tract:

  • motor cortex -> corona radiata -> internal capsule -> crus cerebri -> pons -> pyramid
  • 95% decussate (lateral corticospinal tract) - anterior is those that don't
• specific areas of the motor cortex correspond with specific areas of the body
• corticobulbar tract:

  • synapses at motor nuclei within the brain stem
  • cranial nerves
• rubrospinal tract:

  • cell bodies in red nucleus
  • fine motor control
  • excites flexor muscles, inhibits extensor muscles
• tectospinal tract:

  • cell bodies in superior colliculus
  • controls reflex movement in response to visual stimuli
• reticulospinal tract:

  • doesn't originate from a nucleus but from the general brainstem
  • automatic movement like locomotion
• vestibulospinal tract:

  • from vestibular nuclei in pons and medulla
  • balance and posture
• basal ganglia is made up of the putamen, caudate nucleus and the globus pallidus

  • inhibits unwanted movements
  • affected in parkinsons