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  1. 1. Movement and the Somatic Nervous System Jim Pierce Bi 145a Lecture 8, 10-11
  2. 2. Muscles and Joints <ul><li>With each moveable joint comes a set of muscles </li></ul><ul><li>These muscles have an origin and an insertion (usually into bone) </li></ul><ul><li>How does a muscle move a joint? </li></ul>
  3. 3. Force Generating Axis <ul><li>Muscle fibers generate force </li></ul><ul><li>The muscle organ generates a force which is the vector sum of the forces of its fibers </li></ul><ul><li>The magnitude of that force is often erroneously called “force” </li></ul><ul><li>The direction of that force is called the Force Generating Axis </li></ul>
  4. 4. Force Generating Axis Deltoid Muscle
  5. 5. Force Generating Axis Fiber Force Vectors
  6. 6. Force Generating Axis Muscle Force
  7. 7. Types of Muscle <ul><li>Muscles come with all different fiber orientations! </li></ul><ul><li>Longitudinal – All fibers run parallel </li></ul><ul><li>Pennate – Some Fibers are at an angle </li></ul><ul><ul><li>Unipennate – All fibers are at one angle relative to the Force Generating Axis </li></ul></ul><ul><ul><li>Multipennate – Fibers run at multiple angles relative to the Force Generating Axis </li></ul></ul>
  8. 8. Types of Muscle Strap (a.k.a. Parallel) Fusiform (a.k.a. Spindle Shaped) Unipennate Bipennate Multipennate
  9. 9. Types of Muscle <ul><li>Muscle (organs) come in different shapes </li></ul><ul><ul><li>Flat / Strap </li></ul></ul><ul><ul><li>Flat / Quadrate </li></ul></ul><ul><ul><li>Fusiform </li></ul></ul><ul><ul><li>Convergent </li></ul></ul><ul><ul><li>Sphincter / Circular </li></ul></ul><ul><ul><li>Pennate </li></ul></ul>
  10. 10. Types of Muscle
  11. 11. Muscle Organ <ul><li>All these different shapes operate under the same principle: </li></ul><ul><li>Total Force is produced the Force Generating Axis </li></ul>
  12. 12. Force Generating Axis Tendon / Insertion
  13. 13. Muscle Insertion <ul><li>What happens if the force generating axis does not have the same direction as the tendon? </li></ul>The “rest” of the muscle will tighten or move! Hence… “Butt Wiggling”
  14. 14. Example <ul><li>The Buttocks demonstrate these concepts </li></ul>Scary!
  15. 15. Gluteus Maximus
  16. 16. Gluteus Maximus Clench your butt - Notice your knee move When you use the muscle, the output is through the tendon
  17. 17. Gluteus Maximus When your primary goal is walking, You will still get “ butt movement”
  18. 18. Gluteus Minimus <ul><li>Gluteus Minimus and Medius hide under Maximus </li></ul><ul><li>They spread the legs </li></ul>
  19. 19. Gluteus Minimus During relaxation, the femur neck supports body weight
  20. 20. Gluteus Minimus During contraction the femur head rotates around the hip joint
  21. 21. Joint Function <ul><li>The Skeleton is designed to: </li></ul><ul><ul><li>Support weight across joints </li></ul></ul><ul><ul><li>Resist Fracture </li></ul></ul><ul><li>The Muscles are designed to: </li></ul><ul><ul><li>Produce movement across joints </li></ul></ul><ul><ul><li>Have active and passive properties </li></ul></ul>
  22. 22. Joint Function <ul><li>Crossing each joint are multiple muscles </li></ul><ul><ul><li>By having its own origin and insertion, each muscle creates a unique torque </li></ul></ul><ul><ul><li>Muscles are paired (flexor – extensor) or grouped (Quads and Hamstrings) so that all muscles, at light contraction, balance the joint in anatomic position </li></ul></ul>
  23. 23. Joint Function <ul><li>Together, </li></ul><ul><li>the skeleton and these muscles produce joint function </li></ul>
  24. 24. Nervous System <ul><li>Central Nervous System </li></ul><ul><ul><li>All the parts of the nervous system that are INSIDE of bone </li></ul></ul><ul><li>Peripheral Nervous System </li></ul><ul><ul><li>All the parts of the nervous system that are OUTSIDE of bone </li></ul></ul>
  25. 25. Peripheral Nerve Axons
  26. 26. Peripheral Nerve
  27. 27. Peripheral Nerve <ul><li>We can follow the axon to find the other parts </li></ul>
  28. 28. Peripheral Nerve <ul><li>We find TWO TYPES of neuron </li></ul><ul><li>Dorsal Location </li></ul><ul><li>Ventral Location </li></ul>
  29. 29. Sensory Neuron <ul><li>Dorsal Location </li></ul><ul><ul><li>Dendrites in the Body </li></ul></ul><ul><ul><li>Soma in Dorsal Root </li></ul></ul><ul><ul><li>Synapse in Spinal Cord </li></ul></ul>
  30. 30. Motor Neuron <ul><li>Ventral Location </li></ul><ul><ul><li>Dendrites and Soma in Spinal Cord </li></ul></ul><ul><ul><li>Synapse in Muscle </li></ul></ul>
  31. 31. Peripheral Nervous System <ul><li>Sensory </li></ul><ul><ul><li>Brings information into the Spinal Cord </li></ul></ul><ul><ul><li>Lives Dorsally </li></ul></ul><ul><li>Motor </li></ul><ul><ul><li>Takes information to the muscle </li></ul></ul><ul><ul><li>Lives Ventrally </li></ul></ul>
  32. 32. Peripheral Nervous System <ul><li>Sensory </li></ul><ul><li>Motor </li></ul>
  33. 33. Motor System <ul><li>Posture </li></ul><ul><li>Movement </li></ul><ul><li>Function </li></ul>
  34. 34. Motor System
  35. 35. Motor System <ul><li>The Motor System has TWO parts: </li></ul><ul><li>The Upper Motor System </li></ul><ul><ul><li>Brain and Spinal Cord </li></ul></ul><ul><ul><li>Planning, Coordinating Movement </li></ul></ul><ul><ul><li>Starting, Stopping Movement </li></ul></ul>
  36. 36. Motor System <ul><li>The Motor System has TWO parts: </li></ul><ul><li>The Lower Motor System </li></ul><ul><ul><li>Spinal Cord, Peripheral Nerve, Muscle </li></ul></ul><ul><ul><li>Making Muscles Contract </li></ul></ul><ul><ul><li>Making Body Parts Move </li></ul></ul>
  37. 37. Motor System <ul><li>Upper Motor System </li></ul><ul><li>Lower Motor System </li></ul>
  38. 38. Lower Motor System Lower Motor Neuron
  39. 39. Lower Motor System <ul><li>The Lower Motor System is made up of Motor Units </li></ul><ul><li>Each Motor Unit is a Lower Motor Neuron and all the muscles it controls </li></ul>
  40. 40. Lower Motor System <ul><li>Dendrites </li></ul><ul><li>Soma </li></ul><ul><li>Axon </li></ul><ul><li>“ Muscle Synapse” (Neuromuscular Junction) </li></ul><ul><li>Muscle </li></ul>Lower Motor Neuron Muscle
  41. 41. Neuromuscular Junction Muscle Synapse
  42. 42. Action Potential vs Contraction <ul><li>Action Potential = RED </li></ul><ul><li>Muscle Force = BLACK </li></ul>
  43. 43. Action Potential vs Contraction <ul><li>Lower Frequency = Less Force </li></ul><ul><li>Higher Frequency = More Force </li></ul>
  44. 44. Lower Motor System <ul><li>The Neuron of each motor unit… </li></ul><ul><li>Tells the muscle when to contract and how much force to make </li></ul><ul><li>What do the Soma and Dendrites do? </li></ul>
  45. 45. Lower Motor System <ul><li>Dendrites and Soma = Receive Input </li></ul><ul><li>Axon Hillock = Make Decision </li></ul><ul><li>Together, they listen to the Upper and Lower Motor Systems, and decide when to activate the muscle </li></ul>
  46. 46. Lower Motor System <ul><li>Examples of the decision: </li></ul><ul><li>Brain says move </li></ul><ul><li>Action potential arrives through Spinal Cord </li></ul><ul><li>Lower Motor Neuron Tells muscle to Contract </li></ul>
  47. 47. Lower Motor System <ul><li>Examples of the decision: </li></ul><ul><li>Brain says STOP </li></ul><ul><li>Fewer action potentials arrive via Spinal Cord </li></ul><ul><li>Lower Motor Neuron does not tell muscle to contract </li></ul>
  48. 48. Lower Motor System <ul><li>Key Point: </li></ul><ul><li>The Lower Motor Neuron decides when muscle will contract and relax </li></ul>
  49. 49. Lower Motor System <ul><li>Why this separation? </li></ul>
  50. 50. Lower Motor System <ul><li>Upper MS says “BEND ARM” to </li></ul><ul><ul><li>Bicep Lower MS </li></ul></ul><ul><ul><li>Tricep Lower MS </li></ul></ul><ul><li>Bicep Lower MS says “CONTRACT” </li></ul><ul><li>Tricep Lower MS says “RELAX” </li></ul>
  51. 51. Motor System <ul><li>This is a common theme: </li></ul><ul><li>There are many levels of control </li></ul><ul><li>Higher levels do more complex things </li></ul><ul><li>Lower levels do more simple things </li></ul>
  52. 52. Lower Motor System
  53. 53. Upper Motor System <ul><li>Why have an upper motor system? </li></ul><ul><li>We need to: </li></ul><ul><ul><li>Plan and rehearse movement </li></ul></ul><ul><ul><li>Remember practiced movements </li></ul></ul><ul><ul><li>Coordinate complex movements </li></ul></ul><ul><ul><li>Start Stop movements </li></ul></ul>
  54. 54. Upper Motor System EXECUTE PLAN
  55. 55. Upper Motor System PLAN START AND STOP EXECUTE
  57. 57. Upper Motor System <ul><li>The first clue came from brain injury </li></ul><ul><li>People with injury to the area in RED couldn’t move </li></ul>
  58. 58. Upper Motor System <ul><li>Thus, the RED area is called… </li></ul><ul><li>PRIMARY MOTOR CORTEX </li></ul>
  59. 59. Upper Motor System <ul><li>Injury to Specific Areas Causes Specific Motor Dysfunction </li></ul>
  60. 60. Upper Motor System <ul><li>Activation of Specific Areas Causes Specific Movements </li></ul>
  61. 61. Upper Motor System <ul><li>Mapping is now done by fMRI </li></ul><ul><li>This is a person moving his thumb </li></ul>
  62. 62. Cortex <ul><li>Cortex (in general) </li></ul><ul><li>Made up of layers: </li></ul><ul><ul><li>White matter = Wires </li></ul></ul><ul><ul><li>Grey Matter = Cells </li></ul></ul><ul><ul><li>Gyri (gyrus) = Peaks </li></ul></ul><ul><ul><li>Sulci (sulcus) = Valley </li></ul></ul>
  63. 63. Cortex Carefully looking at the grey matter, we find cells in layers
  64. 64. Cortex If we look closely at any cortex… We find an important cell The Pyramidal Cell
  65. 65. Primary Motor Cortex <ul><li>If we follow the AXON of the pyramidal cell… </li></ul><ul><li>Cerebral White Matter </li></ul><ul><li>Brain Stem White Matter </li></ul><ul><li>Crosses to Opposite Side </li></ul><ul><li>Spinal Cord White Matter </li></ul><ul><li>Synapses with the Lower Motor Neuron (and others) </li></ul>
  66. 66. Upper Motor System <ul><li>Just like the Lower Motor Neuron is the central part of the Lower Motor System </li></ul><ul><li>The Pyramidal Cell of the Primary Motor Cortex is the central part of the Upper Motor System </li></ul>
  67. 67. Lower Motor System <ul><li>Pyramidal Neuron says “BEND ARM” to </li></ul><ul><ul><li>Bicep Lower MS </li></ul></ul><ul><ul><li>Tricep Lower MS </li></ul></ul><ul><li>Bicep Lower MS says “CONTRACT” </li></ul><ul><li>Tricep Lower MS says “RELAX” </li></ul>
  68. 68. Upper Motor System <ul><li>Brain Injury, fMRI, and Stimulation identified other important areas </li></ul><ul><li>BLUE = Premotor Cortex </li></ul><ul><li>ORANGE = Supplementary Motor Cortex </li></ul>
  69. 69. Upper Motor System <ul><li>Further fMRI and ablation studies identified that Pre-motor and Supplementary Motor Cortex… </li></ul><ul><li>Were necessary for: </li></ul><ul><ul><li>Complex Motor Skills </li></ul></ul><ul><ul><li>Planning Motor Skills </li></ul></ul><ul><ul><li>Rehearsal of Motor Skills </li></ul></ul>
  70. 70. Upper Motor System Pre-Motor “ FLEX ARM” UMN – Hand “ Fist” UMN – Wrist “ Turn in” UMN – Elbow “90 Degrees” UMN – Shoulder “Out to Side” UMN – Tricep “ Really Contract” UMN – Bicep “Really Contract” LMN - Deltoid LMN – Hand Intrinsics LMN – Wrist Flexors LMN - Tricep LMN - Bicep LMN - Latissimus
  71. 71. Upper Motor System <ul><li>There is more to complex motor skills than just coordinating the muscles… </li></ul><ul><li>We need to pay attention to our SENSORY system. </li></ul><ul><li>We need to plan our movements accordingly. </li></ul>
  72. 72. Upper Motor System
  73. 73. Upper Motor System <ul><li>Key Point: </li></ul><ul><li>The motor system is like an army! </li></ul><ul><li>To get a more complex skill, We add a higher rank. </li></ul>
  74. 74. Upper Motor System <ul><li>How can we coordinate this movement? </li></ul><ul><li>Some system needs to check ALL the inputs and outputs </li></ul><ul><li>Then it needs to give feedback. </li></ul>
  75. 75. Upper Motor System <ul><li>Purkinje Cell </li></ul>
  76. 76. Cerebellum <ul><li>There is a circuit that travels from Motor Cortex to Cerebellum </li></ul>
  77. 77. Upper Motor System Cerebellum
  78. 78. Cerebellum <ul><li>Everything is an input (orange wires) </li></ul><ul><li>Purkinje cells are the “THERMOSTAT” </li></ul>
  79. 79. Cerebellum <ul><li>The cerebellum coordinates movement by checking everything and giving feedback. </li></ul>
  80. 80. Upper Motor System <ul><li>How do we get started? </li></ul><ul><li>RAS = Keeps brain awake </li></ul>
  81. 81. Upper Motor System <ul><li>Basal Ganglia </li></ul>
  82. 82. Basal Ganglia <ul><li>Main Parts: </li></ul><ul><li>Caudate </li></ul><ul><li>Putamen </li></ul><ul><li>Globus Pallidus </li></ul>
  83. 83. Basal Ganglia
  85. 85. Basal Ganglia <ul><li>Globus Pallidus keeps all movement OFF </li></ul><ul><li>Caudate and Putamen turns G.P. OFF… </li></ul><ul><li>Which turns Cortex ON! </li></ul>It’s like a race car revving its engine: putting the car in gear starts the car!
  86. 86. Basal Ganglia <ul><li>Caudate and Putamen are under two controls: </li></ul><ul><li>SENSORY </li></ul><ul><li>SUBSTANTIA NIGRA </li></ul>
  87. 87. Substantia Nigra <ul><li>Substantia Nigra is responsible for letting the Caudate and Putamen start and stop behaviors. </li></ul><ul><li>Diseases of the S.N. cause MOVEMENT DISORDERS </li></ul>
  88. 88. Upper Motor System
  89. 89. Questions?