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Movement (Ventromedial Pathways (Tracts (vestibulospinal tract (balance),…

- - - - balance
    - - orienting reflexes for head
    - - posture & locomotion
- - - - pyramidal tracts
      - limbs
      - fine motor movement (digits)
      - synapse on motor neurons innervating distal muscles & flexors
      - lesions
        
        difficulty moving distal limbs (may recover)
        
        loss of ability to make independent finger movements (does not recover)
    - - distal limb muscles
      - small in humans
      - synapse on motor neurons innervating distal muscles & flexors
    - - travels w/ CST provides UMN innervation to LMN in cranial nerve motor nuclei
      - face, jaw, tongue, and throat
- - - - origin of corticospinal
      - initiation of complex voluntary movement
    - - acitivity encodes force & direction of movement
      - direction vectors: higher firing rate = more force
        
        points in the preferred direction for neuron, but it's length depends on firing rate over a range of direction
      - population: vector sum
      - direction of movement is encoded by populations of cortical neurons
- - - - motor deficits with loss of substantia nigra
        
        i.e. parkinson's – progressive loss of neurons
        
        i.e. frozen addicts – one time loss so remaining neurons compensate
  - - - degeneration of dopaminergic cells in substantia nigra
    - - loss of tonic inhibitory output to thalamus, cell loss in subthalamus
- - - - connect w/ tens of thousands of purkinje cells, relaying weak sensory information
    - - provide profuse innervation to single purkinje cell, indicating motor error & long-term weakening of co-incident parallel fiber input