2 Motor I

• Cerebral Cortex


  • Cortical Motor Areas
  • Cortical Homonculus

  
• Basal Nuclei


  • Corpus Striatum
  • Direct vs. Indirect Pathways
  • Hypokinetic Disorders
  • Hyperkinetic Disorders

  
• Cerebellum


  • Divisions of Cerebellum
  • Motor Dysfunctions in Cerebrall Disease

  
• Descending Motor Pathways


  • Lateral Corticospinal
  • Medial Corticospinal
• Motor cranial nerves


  Allow you to perform motor activities of your face, pharynx, larynx, etc.

  
• Idea


  Precedes muscle contraction
• Special senses


  • Special somatic (vision, audition)
  • Special visceral (gustation, olfaction)
  • Special somatic afferent (equilibration)
• Cortical association area


  Analyzes modality of sensation, location, intensity, time/duration, texture, color
• Tracts formed before sending impulses to spinal cord


  1. Corticospinal tract

  2. Corticobulbar tract
• Bell-Magendie law


  Anterior is motor
• Motor cranial nerves


  • CN III, IV, V, VI, VII, IX, X, XI, XII
• Some motor cranial nerves are not part of the corticobulbar tract
• Autonomic Nervous System


  Both sensory and motor (reflex/involuntary)
• Somatic NS


  Both sensory and motor
• Somatic Motor


  Effectors are skeletal muscle, making it voluntary
• Basal nuclei


  Provide feedback (e.g. checking if movement is correct)
• Cerebellum


  Provides feedforward (planning of movement)
• Activities where cerebellum and basal nuclei are involved


  • Playing badminton or basketball
• Divisions of cerebellum


  • Neocerebellum/cortico/cerebrocerebellum
  • Spinocerebellum/Palecerebellum
  • Intermediate paravermal cerebellum
  • Floculonodular lobe
  • Vermis of cerebellum

  
• Lateral cerebellum


  Responsible for planning movements with the premotor area
• Motor areas


  Frontal lobe of the cerebrum

  
• Intermediate cerebellum


  Also known as the paleocerebellum
• Lateral cerebellum


  Also known as the neocerebellum
• Vermis of cerebellum


  Responsible for antigravity muscles (head, neck, proximal extremities)
• Supplementary motor area


  Plans movements, then executes via corticospinal or corticobulbar tract
• Cerebral cortex, basal nuclei, cerebellum, brainstem, spinal cord


  • Neural areas that control motor function

  
• Cortical Motor Areas


  • Primary motor area
  • Premotor area
  • Supplementary motor area
• Motor cortex


  Anterior to central sulcus, occupies posterior 1/3 of frontal lobe

  
• Primary motor area


  Responsible for conducting muscle activity, generation of appropriate force levels
• Premotor area


  Responsible for planning of complex motor movements
• Complex movements planned by premotor area


  • Flexion-extension-flexion-extension of limb
• Premotor area subdivisions


  • Dorsal division (PMd)
  • Ventral division (PMv)
• Supplementary motor area


  Responsible for mental rehearsal of complex movements
• Supplementary motor area subdivisions


  • SMA proper (complete somatotopic map, contributes to corticospinal tract)
  • Pre-SMA (connected to prefrontal cortex)

  
• Posterior parietal cortex

  • Produces motor responses, projects to premotor and supplementary areas

  
• Cingulate motor areas


  • Dorsal, ventral, and rostral subdivisions
  • Somatotopic maps, contribute to corticospinal tract

  
• Cortical efferent zones or motor homunculus


  Inverted representation of the body

  
• Cingulate motor areas


  • Located within the cingulate sulcus at approximately the same anterior-posterior level as the SMA
  • 3 cingulate motor areas: dorsal, ventral, rostral
  • Each contains somatotopic map and contributes to the corticospinal tract

  
• Cortical efferent zones or motor homunculus


  • Graphic form that represents somatotopic organization
  • Distortion of the various body parts indicates approximately how much of the cortex is devoted to their motor control

  
• In the sensory homunculus, the face (specifically the lips) and hands (specifically the thumb) are greatly represented