Medical neuroscience

1. Domina Petric, MD

2. › Sceletal muscles are the effector systems for
somatic motor system.
› Lower motor neurons innervate sceletal muscles.
› Upper motor neurons exist in the motor cortex and
the brainstem.
› The motor cortex is the posterior part of the frontal
lobe: executive functions are integrating sensory,
emotion, mnemonic signals and plans for the
production of behavior.

3. Upper motor neurons in the brainstem
are involved in setting the stage for the
execution of the voluntary movement.
Basal ganglia are concerned with gating
proper initiation of movement.
Cerebellum is concerned with sensory
motor coordination and ongoing
movement.

4. Upper motor neurons
(descending systems):
a) Motor cortex (planing,
initiating and directing
voluntary movements)
b) Brainstem centers (basic
movements and postural
control)
Basal ganglia: gating
proper initiation of
movement
Cerebellum: sensory
motor coordination
and ongoing
movement
Local circuit neurons:
lower motor neuron
integration
Motor neuron pools: lower
motor neurons
Sceletal
muscles
Sensory
inputs

5. › Laminae VII-IX: lower motor neurons.
› Cervical enlargement: upper extremities.
› Lumbosacral enlargement: lower extremities.
› There is somatotopy in the ventral horn: in more
medial parts of the ventral horn are the neurons that
are supplying more proximal muscles of the extremity
(for example, shoulder muscles of the hand).
› More lateral in the ventral horn are neurons that supply
more distal muscles of the extremity (for example,
hand muscles).

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7. single alfa motor neuron
muscle fibers innervated by
that sigle alfa motor neuron

8. Slow motor unit: generate less force
slowly.
Fast fatigue resistant: generate
significant amount of force more quickly.
Fast fatigable: generate much larger
amount of force very rapidly.

9. Slow motor unit can maintain its
maximum amount of force production for
a very long period of time.
Fast fatigue resistant motor unit can
maintain its amount of force production
for several minutes.
Fast fatigable motor unit generate the
most force very quickly, but fatigue
rapidly.

10. Slow motor
unit
Standing
Fast fatigue
resistant
Walking
Running
Fast
fatigable
Jumping
Runing
fast
Sequential progression
Fast fatigable
motor units are
the largest.

11. https://www.coursera.org/learn/medical-
neuroscience/lecture: Leonard E. White,
PhD, Duke University
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