Lecture 4 - Neuromuscular 2 Flashcards
Parts of the CNS
Brain
- > Cerebrum
- > diencephalon
- > cerebellum
- > brain stem
Spinal Cord (lowest part of brain stem)
- > midbrain
- > pons
- > medulla oblongata
what information is processed prior to movement
- body position in space (parietal lobe)
- goal and appropriate strategy for attaining goal is formed (ant. portion of frontal lobe)
- Memories of past strategies are reflected upon (temporal lobe)
where is information sent for processing prior to initiating movement
information is sent to the basal ganglia for processing
- > once processed, info is returned to the motor cortex via the thalamus
what happens once all information is processed and we begin movement
Subcortical and cortical motivation areas send rough draft of the movement to the cerebellum and basal ganglia
- > this rough draft is converted into a movement plan (cerebellum: fast movements; BG: slow deliberate movmt)
- > the message is forwarded to motor cortex via the thalamus
- > the message is then sent down spinal neurons for spinal tuning and onto muscles
- > muscle receptors and proprioceptors send feedback for fine tuning of motor control
role of cerebellum in coordination of movement
- > receives information about intended movement from the sensory and motor cortexes
- > returns information to motor cortex regarding required direction, force, and duration of movement
how does the brain connect to the spinal cord
it is connected to the spinal cord via
- > 12 pairs of cranial nerves (connect to brain)
- > 31 pairs of spinal nerves (connect to spinal cord)
- > both types directly supply skeletal muscles
sensory division of the nervous system
- > transmits info from periphery to the brain
major families of sensory receptors
Mechanoreceptors
- > measure physical forces
Thermoreceptors
- > measure temp
Nociceptors
- > pain
Photoreceptors
- > light
Chemoreceptors
- > measure chemical stimuli
List the special families of sensory receptors and what they do
Joint kinesthetic receptors
- > sensitive to joint angles and rate of angle changes
- > senses joint position/movement
Muscle spindles
- > senses muscle stretch
- > sensitive to velocity
Golgi tendon organs
- > sensitive to tension in tendon
- > senses strength of contraction
motor division of PNS and its subclasses
- > transmits information from brain to periphery
Broken down into 2 divisions
Autonomic: regulates visceral activity
Somatic: stimulates skeletal muscle activity
what does the ANS do and regulate
it controls involuntary internal functions and regulates exercise related autonomic functions like:
- > HR, BP and lung functions
divisions of the ANS
sympathetic and parasympathetic nervous systems
sympathetic vs parasympathetic responses
fight or flight
Sympathetic stimulation (fight)
- > inc. HR, BP, BF to muscles, airway diameter, ect.
Parasympathetic response (rest and digest)
- > active at rest and opposes symp. response
- > incr. digestion and urination, conservation of energy
Sensory-Motor integration
process of communication and interaction between sensory and motor systems
Five sequential steps to Sensory-Motor integration
- Stimulus is sensed by sensory receptors
- Sensory AP sent on sensory neurons to CNS
- CNS interprets sensory information, sends out response
- Motor AP sent our on alpha-motor neurons
- Motor AP arrives at skeletal muscle, response occurs
can sensory input be integrated at many points in the CNS? If so, where?
YES, complexity of integration increases with ascent through the CNS
- > spinal cord
- > lower brain stem
- > cerebellum
- > thalamus
- > cerebral cortex (primary sensory cortex)
Motor reflex
instant, pre-programmed response to a given stimulus
- > response to stimulus is identical every time
- > occurs before conscious awareness
- > impulse generated at lower, simple levels
muscle spindles
specialized intrafusal muscle fibres
- > diff form normal (extrafusal) muscle fibres
- > sensory receptors for muscle fibre stretch
what happens when a muscle spindle is stretched
synapses in spinal cord with an alpha-motor neuron trigger a reflex muscle contraction
- > prevent further (damaging) stretch
- this is a stretch reflex
what are golgi tendon organs
sensory receptors embedded in tendons
- > sensitive to tension in tendon (strain gauge)
what happens when a golgi tendon organ is stimulated by excessive tension
they work to prevent excessive tension in muscle/tendon by inhibiting the agonists and exciting the antagonist
- > reduces potential for injury
relate fine and gross motor controls to muscle fibres
Fine motor controls use fewer fibres per motor unit and gross motor controls use more
muscle composition of muscles related to its motor unit
fibre types are not mixed within a motor unit, either type 1 OR 2
- > motor neurons may determine fibre type
