1. Control of body movement (skeletal muscle)
    Somatic Motor Pathways
  2. Direct or pyramidal pathway
    Initiate & control precise movements
    Primary motor cortex
  3. Help establish muscle tone & integrate semivoluntary automatic movements
    basal ganglia
  4. Somatic Motor Pathways:
    Helps make movements smooth & helps maintain posture & balance
  5. Originates in primary motor
    cortex (precentral gyrus)
    Direct Motor Pathway
  6. Upper motor neurons project to
    ______ ____ (corticospinal tract)
    or ____________ (corticobulbar
    spinal cord; brainstem
  7. In the diencephalon descending
    axons gather together to form
    __________ _______
    Internal Capsule
  8. Details of Direct Motor Pathway:
    In the midbrain the axons from
    the _______ __________
    Cerebral Peduncles
  9. Details of Direct Motor Pathway:
    In the medulla oblongata they form the ________ ________
    Pyramidal Tracts
  10. Details of Direct Motor Pathway:
    Approx. _______% cross to the
    opposite side of the medulla at
    the pyramidal decussation
  11. Details of Direct Motor Pathways:
    Crossed fibers form the _______ ___________ _____
    lateral corticospinal tract
  12. Details of Direct Motor Pathway:
    Uncrossed fibers form the ________ ______
    anterior tract
  13. In the spinal cord the axons from the lateral
    corticospinal tract enter the ________ ______ and synapse on _______ ________
    ventral horn; motor neurons
  14. Axons in the _________ ____________ _____
    cross to the opposite side of the spinal cord
    and synapse on ventral horn motor neurons
    anterior corticospinal tract
  15. Axons from the ______ _____ ____ _____
    project in the ventral root to skeletal muscle
    ventral horn motor neurons
  16. Location of Direct Pathways (2):
    • 1. Lateral corticospinal tract
    • 2. Anterior corticospinal tract
  17. Motor Areas of Cerebral Cortex:
    Precentral gyrus =
    Primary motor area
  18. Controls voluntary contractions of skeletal muscles on other side
    Primary motor area (precentral gyrus)
  19. Primary Motor Cortex:
    Initiates voluntary movement
    Precentral gyrus
  20. Primary Motor Cortex:
    Called upper motor neurons
  21. True or false: Muscles represented unequally (according to the number of motor units)
  22. Primary Motor Cortex:
    Needed if number of motor units in a muscle is high
    More cortical areas
  23. Muscles with high number of motor units (5)
    • 1. Vocal cords
    • 2. Tongue
    • 3. Lips
    • 4. Fingers
    • 5. Thumb
  24. Indirect Pathways (3):
    • 1. Complex polysynaptic circuits
    • 2. Basal Ganglia
    • 3. Cerebellum
  25. Helps to program automatic movement sequences
    -walking and arm swinging
    -set muscle tone by inhibiting other motor circuits
    Basal Ganglia
  26. Damage is characterized by tremors or twitches
    Basal Ganglia
  27. 3 Parts of Basal Ganglia
    • 1. Putamen
    • 2. Globus pallidus
    • 3 Caudate nucleus
  28. Basal Ganglia Pathway:
    Projections to the basal ganglia are from:
    cerebral cortex
  29. Has reciprocal projections to
    midbrain (Substantia nigra, dopamine neurons)
    Basal Ganglia
  30. Projects to the thalamus
    Basal Ganglia
  31. Basal Ganglia Pathway
    Projects to the cerebral cortex
  32. Direct corticospinal pathway projects to ________ and ____ ______ _______
    brainstem; spinal motor neurons
  33. Basal Ganglia Pathway:
    Damage to the basal ganglia
    Parkinson's disease
  34. Cerebellar Pathways:
    Aspects of Function (3):
    • 1. Motor learning
    • 2. Coordinated & skilled movements
    • 3. Posture & equilibrium
  35. Cerebellar Pathways:
    1. What carries proprioceptive sensory inputs
    from the spinal cord and vestibular apparatus (inner ear) & excitatory signals
    determines the final
    Inferior cerebellar peduncle
  36. Cerebellar Pathways:
    2. What carries motor commands from the cerebral cortex via the pontine nuclei
    Middle cerebellar peduncle
  37. Cerebellar Pathways:
    3. What carries motor commands from the cerebellum to brain stem, thalamus, basal ganglia and cerebral cortex
    Superior cerebellar peduncle
  38. Final Common Pathway:
    Receive signals from both
    direct & indirect upper
    motor neurons
    Lower motor neurons
  39. Final Common Pathway:
    Determines the final response of the lower motor neutron & the skeletal muscles
    Sum total of all inhibitory & excitatory signals
  40. Regulates activity of smooth muscle, cardiac muscle & glands
    The Autonomic Nervous System
  41. Involuntary control
    Involves CNS motor neuron (preganglionic neuron) and PNS motor neuron (postganglionic neuron)
    The Autonomic Nervous System
  42. Autonomic vs. Somatic NS:
    2 neuron pathway
    Autonomic Nervous System
  43. Autonomic vs. Somatic NS:
    Pathway contains one neuron
    Somatic Nervous System
  44. What are the 2 divisions of the ANS?
    • 1. Parasympathetic
    • 2. Sympathetic
  45. One speeds up organ
    One slows down organ
    Dual innervation
  46. Increases heart rate
    Sympathetic NS
  47. Decreases heart rate
    Parasympathetic NS
  48. Preganglionic cell bodies
    in thoracic and first 2
    lumbar segments of spinal
    Sympathetic (thoracolumbar) division
  49. Preganglionic cell bodies in
    nuclei of 4 cranial nerves
    and the sacral spinal cord
    Parasympathetic (craniosacral) division
  50. Anatomy of Sympathetic NS:
    Found in lateral horn of thoracic and lumbar spinal cord
    Preganglionic cell bodies
  51. Anatomy of Sympathetic NS:
    Located in paravertebral or prevertebral ganglia
    Postganglionic cell bodies
  52. Anatomy of Parasympathetic NS:
    Where are preganglionic cell bodies found?
    • 1. 4 cranial nerve nuclei in brainstem
    • 2. S2 to S4 spinal cord
  53. Anatomy of Parasympathetic NS:
    Very near or in the wall of the target organ in a terminal ganglia
    Postganglionic cell bodies
  54. Physiological Effects of the ANS:
    Regulates balance (tone) between sympathetic and parasympathetic activity levels
  55. True or false: Some organs have only sympathetic innervation
    • True.
    • Sweat glands, adrenal medulla, arrector pili muscle & many blood vessels
  56. Dominance by the sympathetic system is caused by:
    physical or emotional stress -- "E situations"
  57. What are the "E situations" that cause sympathetic responses
    • 1. Emergency
    • 2. Embarrassment
    • 3. Excitement
    • 4. Exercise
  58. -dilation of pupils
    –increase of heart rate, force of contraction & BP
    –decrease in blood flow to nonessential organs
    –increase in blood flow to skeletal & cardiac muscle
    –airways dilate & respiratory rate increases
    –blood glucose level increase
    Alarm reaction = flight or fight response
  59. Long lasting due to lingering of NE in synaptic gap and release of norepinephrine by the adrenal gland
    Sympathetic Response
  60. Enhance "rest-and-digest" activities
    Mechanisms that help conserve and restore body energy during times of rest
    Normally dominate over sympathetic impulses
    Parasympathetic Response
  61. Parasympathetic Responses:
    SLUDD type responses are:
    • Salivation
    • Lacrimation
    • Urination
    • Digestion
    • Defecation
  62. Parasympathetic Responses:
    3 "decreases"
    • Heart rate
    • Diameter of airways
    • Diameter of pupil
Card Set
Somatic and Autonomic Motor Neurons