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Motor Systems - Coggle Diagram

- - - - Z-line
      - M-Line
      - Titin
    - - Myosin
      - actin
      - tropomyosyn
      - troponyn
      - Motor Contraction
        
        Muscle contraction steps
        
        what are T-tubules
        
        extensions of the cell membrane that are responsible for what 2 things
        
        calcium regulation and electrical excitation
        
        AP caused by Ach, and is carried along the muscle fiber membranes and T-tubules
        
        what is the sacroplasmic reticulum
        
        network of membranes that store and release calcium ions
        
        Ca++ is released from Sarcoplasmatic reticulum
        
        Ca++ binds to troponin starting a cascade where the tropomyosin moves to expose binding sites on actin
        
        Myosin cross-bridges bind to the sites on actin
        
        1 more item...
    - - definition
        
        basic unit of control formed by ONE motor neuron and ALL skeletal muscle fibers innervated by that motor neuron's axonal terminals
      - what do groups of motor units do
        
        work together to coordinate the contractions of a single muscle
      - motor pool
        
        definition
        
        all of the motor units within a muscle
      - Classification (2)
        
        fast twitch
        
        description of alpha motor neurons that innervate these fibers
        
        Larger-diameter, faster-conducting alpha MNs
        
        high or low membrane resistance
        
        low
        
        slow twitch
        
        description of alpha motor neurons that innervate these fibers
        
        Smaller-diameter, slower-conducting alpha MNs
        
        high or low membrane resistance
        
        high
        
        Heneman's Principle
        
        description
        
        MU will be recruited in order of size from smallest to
        largest depending upon intensity
        
        so when is fast-twitch fibers recruited
        
        when more force is needed
    - - Lower Motor Neurons (LMN)
        
        Innervation
        
        Medially located pools innervate
        
        axial and girdle skeletal muscle
        
        Laterally located pools innervate
        
        distal limb muscles
        
        Posterior pools innervate
        
        flexor muscles
        
        where are posterior pools
        
        within the anterior horn
        
        Anterior pools innervate
        
        extensor mm.
        
        the pools may do what
        
        extend several spinal cord segments
        
        Injury of LMNs
        
        signs of LMN lesions (5)
        
        Decrease or loss of reflexes
        
        Paresis or paralysis
        
        Atrophy
        
        Decrease or loss of muscle tone
        
        Fibrillations
        
        1 more item...
    - - Muscle tone
        
        muscle tonus
        
        definiition
        
        Muscles are resistant to passive stretch
        
        depends on 2 factors
        
        Neurological factors
        
        this is...
        
        tissue related
        
        Mechanical factors
        
        this is...
        
        reflex related
        
        what do sarcomeres do related to muscle tonus
        
        adapt to muscle length
        
        are they more resistant if they're shorter or longer
        
        shorter
      - Somatosensory features
        
        muscle somatosensory receptor
        
        muscle spindles
        
        tendon somatosensory receptor
        
        golgi tendon organs (GTOs)
      - Muscle co-contraction
        
        definition
        
        2 mm. contracting at the same time by stimulation of MNs from both groups
        
        what does this do (2)
        
        increase resistance to movement and stability of joint
      - Reciprocal Inhibition
        
        definition
        
        inhibition of antagonist muscles during agonist contraction
        
        how is this achieved
        
        by interneurons in the spinal cord that link MNs into functional groups
      - Reflexes
        
        Components (5)
        
        receptor
        
        what are the primary sensory receptors (2)
        
        muscle spindles and GTOs
        
        afferent route
        
        synapse (or more than one)
        
        where does this usually occur
        
        @ level in spinal cord
        
        efferent limb
        
        what are the 2 efferent limbs
        
        alpha and gamma motor neurons
        
        effector
        
        what is this
        
        the muscle
        
        Types (3)
        
        Monosynaptic
        
        aka
        
        stretch reflex
        
        ex
        
        1 more item...
        
        involves how many synapses
        
        1
        
        Oligosynaptic
        
        involves how many synapses
        
        involves a small number of synapses, usually two or three
        
        Polysynaptic
        
        aka
        
        Withdrawal reflex
        
        description
        
        1 more item...
        
        involves how many synapses
        
        more than 6
  - - - group of muscles innervated by a single spinal nerve
  - - - Motor Neurons bridge the communication between the Spinal Cord and muscle fibers
    - - Extrafusal fibers
        
        description
        
        make up the majority of the muscle, and are responsible for generating force and allowing for movement
        
        2 examples
        
        slow twitch and fast twitch
    - - Intrafusal fibers
        
        description
        
        located inside the muscle spindle, and are innervated by both sensory and motor fibers
    - - the only 2 types of MNs
- - - - Communication between CNS areas and neurons located either in the Spinal Cord or Cranial Nerves
    - - cerebellum and motor basal ganglia
    - - , interactions among signals from somatosensory neurons and in brainstem & spinal cord
  - - - degenerates of tract occurs in which disease
        
        ALS
    - - Postural/gross movement tracts (4)
        
        what do they do
        
        Control automatic skeletal muscle activity
        
        aka
        
        Extrapyramidal tracts
        
        Reticulospinal tract
        
        what does it involve (3)
        
        pathway for neck reflexes in response to visual or auditory input
        
        how does this happen
        
        the colliculi in the posterior midbrain process the visual or auditory info and signal the reticulospinal neurons that facilitate MNs that innervate neck muscles
        
        postural and gross limb movement
        
        how does it do that
        
        by facilitating bilateral MNs innervating postural and gross limb movement mm. T/O body
        
        coordinate m. activity during walking
        
        how
        
        by coordinating the trunk and the proximal muscles of all four limbs during walking
        
        where does this tract begin
        
        in reticular formation in brainstem
        
        Medial vestibular tract
        
        what does the Medial vestibular nuclei receive
        
        info about head movement and position from the vestibular apparatus
        
        where is the vestibular apparatus located
        
        inner ear
        
        where does tract originate
        
        in the medial vestibular nucleus
        
        where does it go from there
        
        projects bilaterally to the cervical and thoracic spinal cord
        
        1 more item...
        
        Medial Corticospinal tract
        
        pathway (3 steps)
        
        descends from the cortex through the internal capsule and the anterior brainstem
        
        Individual medial corticospinal axons project to the ipsilateral, contralateral, and bilateral spinal cord
        
        Medial corticospinal neurons synapse with MNs that control which mm. (3 regions)
        
        1 more item...
        
        direct connection from where
        
        cerebral cortex
        
        Lateral Vestibulospinal tract
        
        what does the lateral vestibular nuclei respond to
        
        gravity information from the vestibular apparatus
        
        what does it specifically do
        
        facilitate ipsilateral MNs to extensors while inhibiting ipsilateral MNs to flexors
        
        what is the tract doing when a person is upright
        
        the tract is continuously active
        
        why
        
        to maintain COG over BOS, responding to the slightest destabilization
      - Fine movement tracts (2)
        
        what do they do
        
        Control fractionated movements of limbs and face
        
        aka
        
        Pyramidal tracts
        
        Lateral corticospinal tract
        
        this involves innervation to which body parts'
        
        distal areas that involve fine motor movements'
        
        where do they descend from
        
        descend in the lateral spinal cord
        
        what do they synapse with
        
        synapse with laterally located MN pools in ventral horn
        
        Corticobulbar tracts :red_cross: (learn the tract)
        
        what does it do
        
        projects to cranial n. nuclei
        
        what part of the body does it innervate
        
        face
    - - causes (5)
        
        SCI, spinal cerebral palsy, MS, trauma, stroke
      - signs of lesions (7)
        
        •Paresis and paralysis
        • Abnormal reflexes
        • Myoplasticity
        • Abnormal muscle tone
        •Loss of fractionated movements
        • Abnormal cocontraction
        •Abnormal muscle synergies