Motor axis

• Motor cortex:

  • location: frontal lobe
  • responsibilities: planning, controlling, executing movements
• Types of movement?

  • voluntary movement (putting a thought into action)--> pyramidal tract (corticospinal + corticobulbar)
  • involuntary --> basal ganglia
• Corticospinal tract: from motor cortex to spine
• Upper motor neuron (upm) in corticospinal tract: sends signals to Lower motor neuron (lmn)
• Lateral corticospinal tract --> movements of limbs Anterior corticospinal tract --> movements of the trunk of the body
• Lesions of UPL:

  • loss of voluntary movements
  • Increased muscle tone and reflexes
• LMN --> link between UMN and muscles

  location:

  • ventral horn for the muscles of the body
  • cranial nerve nuclei of the brainstem for the muscles of the head and neck
• SPINAL lower motor neurons:

  • all voluntary movement relies on them
  • alpha, beta, gamma types
• INTERneurons: for the fine movements (lateral corticospinal tract) and trunk movements (anterior corticospinal tract)
• Lesions of LOWER motor neurons --> everything is decreased!

  • decreased muscle tone
  • decreased reflexes
  • flaccid paralysis and muscle atrophy
  • Babinsky reflex is negative
• Basal ganglia: control the SCALE of voluntary movement + combining planning with action
• DIRECT pathway of basal ganglia:

  • ALLOWS us to make the WANTED movements --> excites motor cortex
  • D1 receptors on axons of striatum
• INDIRECT pathway:

  • allows us NOT to make UNWANTED MOVEMENTS --> INHIBITS MOTOR CORTEX
  • D2 receptors on axons of striatum
• DIRECT pathway dysfunctions:

  • hyperkinesia -->rapid repetitivee movements
  • decreased muscle tone
  • cognitive changes
• INDIRECT pathway dysfunctions:

  • Parkinson's disease --> hypokinesia (slow decreased movements)
  • TRAP: tremor, rigidity, akinesia postural instability
• CEREBELLUM:

  • Control of equilibrium and informator on: muscle's position and tone, how fast movement is happening and in which direction
  • relays planned sequences of movement --> dance
  • has influence of interneurons for those fine and precise movements
• Lesion of CEREBELLUM:

  • disturbed equilibrium
  • intention tremor
  • dysmetria, ataxia