Cerebellum and Basal Ganglia

• Cerebellum Functions:

  • refinement of skills
  • maintains normal body posture
  • coordinates all reflexes and voluntary muscular activities
  • graduates and harmonizes muscle tone
• Molecular layer:

  • basket and stellate cells are found
  • outermost layer
• Purkinje cell layer:

  • purkinje cells
• Granular layer:

  • granule and golgi cells are found
  • innermost layer
• 6 layers:

  1. molecular - contains molecular, purkinje, and granular layers
  2. external granular
  3. external pyramidal
  4. internal granular
  5. internal pyramidal - contains Betz cells
  6. Multiform
• Purkinje cells:

  • basic unit of cerebellum
  • only efferent/output cells
• Basket cells - inhibitory; GABA neurotransmitter
• Stellate cells - inhibitory; Taurine neurotransmitter
• Purkinje cells - inhibitory; GABA neurotransmitter
• Granule cells - excitatory; Glutamate neurotransmitter
• Golgi cells - inhibitory; GABA neurotransmitter
• Vermis - connection of 2 cerebellar hemispheres

  • Arbor Vitae (tree of life) - branches of white matter
• Anterior cerebellar lobe (superior) - most superior lobe
• Posterior cerebellar lobe (middle) - largest lobe
• Flocculonodular cerebellar lobe (inferior) - most anterior lobe

  • connects to brainstem
  • smallest lobe
• Primary fissure - divides anterior and posterior lobe
• Uvulonodular fissure - divides posterior and flocculonodular lobe
• Horizontal fissure - divides superior and inferior part
• Phylogenetic: Archicerebellum

  • functional: vestibuolocerebellum
  • anatomic: flocculonodular - eyes
  • nuclei: fastigial - most medial and smallest
  • function: balance and equillibrium
• Phylogenetic: Paleocerebellum

  • functional: spinocerebellum
  • anatomic: vermis, anterior lobe
  • nuclei: emboliform and globose - interposed
  • function: muscle tone and posture
• Phylogenetic: Neocerebellum

  • functional: cerebrocerebellum
  • anatomic: cerebellar hemisphere, posterior lobe (hand and feet function)
  • nuclei: dentate - most lateral and largest nuclei
  • function: coordination
• Cerebellar peduncle - connects to brainstem
• Superior cerebellar peduncle - Branchium conjunctivum

  • connects midbrain
• Middle cerebellar peduncle - Branchium pontis

  • connects pons
• Inferior cerebellar peduncle - Brachium restiformis

  • connects medulla
• Basal Nuclei (Ganglia) - collections of masses of gray matter within each cerebral hemisphere

  • refines voluntary movements
  • initiation of movement
  • planning and programming of movements
• True/Anatomical structures of Basal Ganglia:

  • caudate
  • putamen
  • globus pallidus
• Physiologic structures of Basal Ganglia:

  • Substantia Nigra (pars reticulata or compacta
  • Subthalmic nucleus
  • Red nucleus
• Caudate + Putamen - Striatum or Neostriatum
• Putamen + Globus Pallidus - Lentiform nucleus
• Globus Pallidus - Paleostriatum
• Caudate + Putamen + Globus Pallidus - Corpus striatum
• Caudate and Putamen - major input/afferent of the basal ganglia
• Globus Pallidus interna and Substantia Nigra pars reticulata - major output/efferent of the basal ganglia
• Dopamine - inhibitory in indirect pathway

  • excitatory in direct pathway
• Asynergia - Loss of ability to associate muscles together for complex movements
• Dyssynergia - Movement performed in a sequence of component parts rather than as a single, smooth activity, decomposition 
• Dysarthria - Disorder of the motor component of speech articulation
• Dysmetria - Inability to judge the distance or range of a movement 
• Hypermetria - Overestimation of distance or range needed to accomplish a movement