BIPN 100 Lecture Notes - Lecture 11: Corticospinal Tract, Pyramidal Tracts, Basal Ganglia
13 Jun 2018
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BIPN 100 Lecture 11
4/25/2018
• Motor pathways
o Carry info from the CNS to the body (PNS) via efferent neurons
o Movement is controlled by the activity of the spinal cord, frontal lobe,
brainstem, and basal ganglia
▪ Involved in producing or modulating the movement
▪ Corticospinal tract: from cortex (frontal lobe) to the spinal cord
• From the cortex to the medulla, crosses the pyramids of the
medulla (hence, pyramidal tracts). One interneuron through the
cortex and medulla, then synapses with a motor neuron in the
spinal cord with the cell body in the ventral horn. Voluntary
movement via an A-alpha motor neuron
▪ Aterior ortiospial trat: does’t deussate util it gets to the spial
cord. The, it can decussate and synapse with a contralateral motor
neuron, or stay and synapse ipsilaterally what they control
▪ Bilateral movement and posture for ?
o Extrapyramidal tract
▪ Does’t cross the edulla’s praids
▪ Goes from the midbrain all the way to the spinal cord, crosses through
the medulla, but not the pyramid. There are 4 tracts. More in control of
iolutar oeet h it does’t oe for the orte
▪ Synapse with a motor neuron in the spinal cord
• Parkiso’s disease
o Progressive, neurological disorder
o Characterized by abnormal movements, speech difficulties, and cognitive
changes
o Loss of substania nigra neurons that release dopamine, which is necessary for
function of basal ganglia neurons
o Mostly affects involuntary movement
o Volutar patha ortiospial is’t as affeted
o Given L-dopa because it can cross the BBB
• Trauma to the spinal cord
o Can lead to loss of sensation and/or loss of involuntary movement
o Happes elo the leel of the ijur, e.g. a ijur to the luar regio o’t
affect what is controlled above the injury of the lumbar area
• Efferent divisions of the PNS
o Somatic motor neurons
▪ Controls skeletal muscles
▪ Mostly voluntary
o Autonomic neurons
▪ Deal with involuntary movement, like reflexes, HR, control of glands,
control of smooth muscle
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