Samenvatting Motorsystemen
1 & 2 – From the cortex to the muscles
Development of the motor system
- There are innate motor programs such as those for swallowing, vomiting, crying,
coughing and sneezing
- The circuits mature within 0 – 15 years of life. Learning by doing an playing under the
influence of sensory systems, vestibular system and muscle and skin receptors.
There is a somatotopic organization of the motor system.
Cortical motor areas:
- Cingulate cortex -> represents
highest level of motor control,
decisions on actions and their
outcomes, abstract thinking,
decision making and expected
outcome of an action.
- Posterior parietal cortex -> where
pathway, coordinate arm
proprioception with the image of
the hand, compute hand position in
vision coordinates and compute
target position in vision coordinates.
- Extra striate cortex -> dorsal: to
parietal cortex (where is the object)
and ventral: to temporal cortex (what is the object)
- Supplementary motor area -> also topographical organization, controls bilateral
contraction: bilateral grip, posture related movement and movements of head and
eye
- Premotor area -> responsible for complex motor patterns, regulate target position in
relation to hand position and coding of the appropriate movement, mirror neurons
- Primary motor cortex (M1) -> puts the appropriate movement in muscle activation
patterns and sends them to the spinal cord
Mirror neurons -> in the premotor area. Neurons fire when you see an action as well as
when you perform that action.
Projection fibers -> corona radiata and internal capsule
,Spinal cord cervical (arms and hands), thoracic (core muscles), lumbar (toes and feet) and
sacral.
Motor pools
- Medial local circuit neuron:
o Long distance
o Project to many spinal cord segments
o Bilateral
o Postural control
o Rhythmic movements upper and lower limbs
o Maintenance of balance
- Lateral local circuit neurons:
o Short distance
o Project to a few spinal cord segments
o Ipsilateral
o Execution of skilled behavior
Reflexes -> spinal cord
, When a flexor contracts the antagonist, extensor is relaxed because of the inhibitory
interneurons which project to the extensor muscle neurons.
Myasthenia gravis -> autoimmune disease in which the nACh receptors on the muscles are
attacked.
Motor unit types:
- Slow motor units -> sustained, upright position
- Fast fatigable resistant motor units -> intermediate
- Fast fatigable motor units-> brief but large forces, jumping
Motor neurons:
- Alpha motor neurons
o Extrafusal muscle fibers
o Striated muscle fibers
o Generate forces needed for posture and movement
- Gamma motor neurons
o Intrafusal muscle fibers
o Combined with sensory input that sends information about the length of the
muscle
o Setting of the appropriate muscle length
Stretch reflex
1 & 2 – From the cortex to the muscles
Development of the motor system
- There are innate motor programs such as those for swallowing, vomiting, crying,
coughing and sneezing
- The circuits mature within 0 – 15 years of life. Learning by doing an playing under the
influence of sensory systems, vestibular system and muscle and skin receptors.
There is a somatotopic organization of the motor system.
Cortical motor areas:
- Cingulate cortex -> represents
highest level of motor control,
decisions on actions and their
outcomes, abstract thinking,
decision making and expected
outcome of an action.
- Posterior parietal cortex -> where
pathway, coordinate arm
proprioception with the image of
the hand, compute hand position in
vision coordinates and compute
target position in vision coordinates.
- Extra striate cortex -> dorsal: to
parietal cortex (where is the object)
and ventral: to temporal cortex (what is the object)
- Supplementary motor area -> also topographical organization, controls bilateral
contraction: bilateral grip, posture related movement and movements of head and
eye
- Premotor area -> responsible for complex motor patterns, regulate target position in
relation to hand position and coding of the appropriate movement, mirror neurons
- Primary motor cortex (M1) -> puts the appropriate movement in muscle activation
patterns and sends them to the spinal cord
Mirror neurons -> in the premotor area. Neurons fire when you see an action as well as
when you perform that action.
Projection fibers -> corona radiata and internal capsule
,Spinal cord cervical (arms and hands), thoracic (core muscles), lumbar (toes and feet) and
sacral.
Motor pools
- Medial local circuit neuron:
o Long distance
o Project to many spinal cord segments
o Bilateral
o Postural control
o Rhythmic movements upper and lower limbs
o Maintenance of balance
- Lateral local circuit neurons:
o Short distance
o Project to a few spinal cord segments
o Ipsilateral
o Execution of skilled behavior
Reflexes -> spinal cord
, When a flexor contracts the antagonist, extensor is relaxed because of the inhibitory
interneurons which project to the extensor muscle neurons.
Myasthenia gravis -> autoimmune disease in which the nACh receptors on the muscles are
attacked.
Motor unit types:
- Slow motor units -> sustained, upright position
- Fast fatigable resistant motor units -> intermediate
- Fast fatigable motor units-> brief but large forces, jumping
Motor neurons:
- Alpha motor neurons
o Extrafusal muscle fibers
o Striated muscle fibers
o Generate forces needed for posture and movement
- Gamma motor neurons
o Intrafusal muscle fibers
o Combined with sensory input that sends information about the length of the
muscle
o Setting of the appropriate muscle length
Stretch reflex
