08. Motor Systems 1

• lateral descending motor pathway = voluntary and direct

  • corticospinal and rubrospinal
• ventromedial descending pathway = brainstem control, complex, posture

  • vestibulospinal, tectospinal, reticulospinal
• posture = proximal and axial muscles innervated by medial motorneurones
• fine motor = distal muscles innervated by lateral motor neurones
• cortical motor areas are right next to sensory areas
• somatotopic representations of the motor cortex show each area responding to a different part of the body
• motor cortex is made up of area 6 and area 4

  • area 6 = supplementary motor area and premotor area
  • area 4 = primary motor cortex (M1)
• primary motor cortex output neurones encode either force or direction of movement

  • damage leads to initial weakness, and then spasticity (increased muscle tone and reflexes)