Muscle Flashcards
Motor Equivalence
the ability (e.g. handwriting) is similar regardless of the limb used due to the internal preimaged style template
Voluntary movement
- governed by conscious planning
- done effortlessly
- goal oriented
- do not need a stimuli/trigger
- is not dictated by sensory stimuli
Motor system follows
hierarchical and parallel processing
Decussation in spinal cord
Sensorymotor transformation
Motor outputs that are derived from sensory outputs; feedback system via spinal bulbar tract
-can be intrinsic (kinematic & kinetic) or extrinsic (spatial location of a target provided by visual and auditory inputs)
Explain Intrinsic sensorimotor transformation
-kinematic 運動学 1a
stretch reflex (direction and velocity)
-kinetic動学 1b
Golgi tendon (and mechanoreceptors) reflex
For stretch reflex, what is the sensory receptor
muscle spindle
How does stretch reflex work
Muscle stretch
- > signal send by afferent sensory endings (Group1a afferent) to muscle spindle
- > leads to signalling alpha and gamma motor neurons
alpha: extrafusal muscle is ready to go -> muscle extends (signals via spinal bulbar tract to the cortex that muscle is activated)
- > activate more alpha motor neuron as well as type 1a inhibitory neuron to antagonistic muscle
gamma: intrafusal muscle (get feedback from cortex as well)
Explain two type of muscle involved in stretch reflex
1-> alpha motor neuron is activated to signal to extrafusal muscle, alpha MN leads to action of extending muscle
2-> in the spinal cord, inhibitory interneuron also send signal to relax the antagonistic muscle
What is kinetic information
the force generated golgi tendon (collagens) are located between muscle and tendon
Opposite of stretch reflex, it protects the muscle from excessively heavy loads by causing the relax of muscle
- > afferent sensory endings (afferent 1beta) on spindle send excitatory signal to the spinal c
- > inhibit alpha motor neuron and excite antagonistic muscle
Relationship of the two reflex
Thestretch reflexoperates as a feedback mechanism to control muscle length by causing muscle contraction. In contrast, thetendon reflexoperates as a negative feedback mechanism to control muscle tension
Primary motor cortex is in area
area 4
in charge of Direction, force and velocity of movement
Areas in the premotor cortex
All three areas project directly to the spinal cord via the corticospinal tract
1. Premotor area (PMA or PMC):
Planning and anticipation of specific motor act
2. Supplementary motor area (SMA):
Programminng of motor sequences
3. Cingulate area
Intentional control of movement
Premotor and supplementary motor cortex also project to the primary motor cortex and are involved in coordinating & planning complex sequences of movement (motor learning).
Dorsal vs ventral route
Dorsal -> “where”organise movement
Ventral ->”what”detect movement
Parallel processing of motor system
Cortex -> internal capsule ->medullal pyramids ->
90% of fibres cross at pyramidal tract, while 10% of fibres cross only at spinal level
done by 3 different tracts
-Corticospinal tract:
Sensory cortex (40%),Primary Motor Cortex (30%), Premotor and Supplementary cortex (30%).
-Lateral corticospinal tract
Limb control mostly
-Ventral corticospinal tract
Proximal muscle control; mostly upper body (e.g. trunk & neck, proximal arm)
Single alpha motor neuron
Alpha motor neuron receive signal from one cortico motor neuron (= received monosynaptic information)
but one cortico motor neuron can be giving to several alpha MN
