final neuro

• lower motor neurons (alpha-motor)

  ventral horn motor neurons, innervate skeletal muscles
• lower motor neurons innervating upper extremities

  located in ventral horn of cervical enlargement
• lower motor neurons innervating lower extremities

  ventral horn of lumbar region of spinal cord
• lower motor neurons innervating trunk

  located in thoracic region
• slow (s) fibers


  red muscle fibers with large number of mitochondria and myoglobin that contracts slowly but sustains contraction
• fast- fatigable fibers


  generate strongest fastest contractions but are quickly exhausted
• fatigue- resistance fibers


  generate moderately strong and fast fibers that are resistant to fatigue
• stretch reflex


  eliminates stretching through 1a fibers to contract flexor muscles and relax extensor
• golgi tendon reflex


  eliminates contraction to regulate muscle tension through 1b sensory neurons causing the contracted muscle to relax while contracting the antagonistic muscle
• flexion- crossed-extension reflex


  activated through pain where Aδ cause the leg to receive this stimulus to flex and the opposite limb extends
• lower motor neuron syndrome symtoms

  paralysis, paresis, areflexia, fibrillations and fasciculations
• upper motor neurons located

  in cerebral cortex and brainstem
• non-betz cells


  97% smaller pyramidal neurons; located within layer 5 of cerebral cortex
• betz cells


  largest neurons and make up 3% to spinal cord and controls fine motor movements- located in layer 5 of cerebral cortex
• rubrospinal tract


  synapses onto the red nucleus after cerebral peduncle and crosses over at level of pons to descend down the spinal cord to synapse onto lower motor neurons
• lateral corticospinal tract


  after the pyramid is formed 90% cross over at caudal medulla to form pyramidal decussation to innervate lower motor neurons
• ventral corticospinal tract


  10% descend to synapse bilaterally in medial ventral horn to innervate back and neck muscles
• corticobulbar tract


  forms pontine fibers and synapses onto lower motor neurons in cranial nerves 5,7,9,12 (all bilaterally except 7)
• upper motor neuron syndrome CX7

  weakening of inferior contralateral side of the face
• lower motor neuron syndrome CX7

  weakening of superior and inferior ipsilateral side of face
• ventromedial pathways

  brainstem upper motor neurons that control posture and balance
• vestibulospinal tract


  maintains posture thru head movements in response to semi-circular canal information
• tectospinal tract


  orienting in response to an image through fovea (eye movements)
• pontine reticulospinal tract


  enhances antigravity reflex thru extensors of lower limbes
• medullary reticulospinal tract


  liberates anti gravity effects from reflex control
• upper motor neuron syndrome symptoms


  weakness, babinski's sign, spinal shock, impaired fine motor movements
• basal ganglia


  group of nuclei deep within cerebral cortex that modulates motor control, includes cadate, putamen, globus pallidus internal and external segments
• parkinson's symptoms


  hypokinetic movement disorder with tremor, bradykinesia, and minimal facial expressions- affects both pathways (diminished substantia nigra)
• huntington's symptoms


  hyperkinetic , involuntary jerky rapid movements - affects indirect pathway ( diminished striatum)
• cerebrocerebellum


  input from the cerebral cortex and regulation of highly skilled movements
• spinocerebellum


  input from spinal cord - vermis and paramedian
• vestibulocerebellum


  input from vestibular nuclei in brainstem- vestibulo ocular reflex and posture and balance
• afferent pathways from brain to cerebellum

  corticopontocerebellar, corticoreticular cerebellar, cortico-olivary, and vestibulocerebellar
• corticopontecerebellar pathway


  neurons in brain go to brainstem to synapse at pontine nuclei and transverse contralaterally to form transverse pontine fibers
• corticoreticular cerebellar pathway


  neurons in brain synapse onto 2nd order neurons in brainstem and synapse ipsilaterally from anterior peduncle
• cortico-olivary pathway


  neurons in brain synapse onto 2nd order neurons in inferior superior olive and synapse onto cerebellum ipsilaterally from inferior peduncle
• vestibulocerebellar tract


  vestibular nerve synapses ipsilaterally onto inferior peduncle
• afferent pathways from spinal cord to cerebrum

  cuneocerebellar, dorsal, rostral, ventral spinocerebellar tracts
• cuneocerebellar tract


  muscle spindle info from upper body enters above t6 and synapse onto 2nd order neurons in medulla to synapse ipsilaterally on cerebellum
• dorsal spinocerebellar tract


  muscle spindle info from lower body 1a sensory neurons enter below t6 and ascend ipsilaterally and synapse into cerebellum and