MMB1 Week 1 Review Part 2

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MMB1 Week 1 Review Part 2
2012-12-22 00:18:02
MBB1 Week Review

MBB1 Week 1 Review
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  1. Cholinergic Signaling in the CNS
    • From: Basal nuclear complex
    • To: cerebral cortex and limbic system
    • Regulates: memory, cognitive function

    • -interneurons in striatum
    • -motor nuclei of the brain stem and spinal cord
    • -preganglionic neurons in the brain stem and spinal cord
    • -nerve cell bodies in the primary motor cortex that project to the motor nuclei
    • in the brain and spinal cord
  2. GABA
    • -inhibitory NT in the brain and spinal cord
    • -action terminated by GAT uptake (repackage or metabolize)
    • -most found in short local inhibitory interneurons in the cerebral cortex and cerebellum
  3. GABA Receptors
    A: "A is for alcohol", ligand-gated chloride channel (benzos and barbs are also agonists)

    B: "B is for baclofen", GPCR that leads to the opening of K channels, used to tx spasticity
  4. Glycine
    • -found only in the spinal cord and brain stem
    • -NT of the inhibitory interneurons in the Golgi tendon organ reflex and in reciprocal inhibition
    • -strychnine is a Glycine receptor antagonist
  5. Glutamate
    • -the major excitatory NT in the CNS
    • -Termination: reuptake by excitatory AA Transporters (EATTs), especially by glial cells
  6. Glutamate receptors
    • 1. AMPA
    • -throughout CNS
    • -ionotropic (Na influx --> EPSP)

    • 2. NMDA
    • -glycine co-agonist (saturated at normal levels)
    • -blocked by Mg at normal Vm (fxns only when depolarized by AMPA EPSPs)
    • -influx of Ca in addition to Na (Ca second messenger effects: long term potentiation/excitotoxicity)
  7. Ventral Roots
    -carry somatic and visceral motor axons
  8. Dorsal Roots
    -somatic and visceral sensory axons
  9. V1 dermatome
  10. V2 dermatome
  11. V3 dermatome
  12. C5-T1 dermatome
    upper extremity
  13. T4/T5 dermatome
    nipple line
  14. L1 dermatome
    below groin
  15. S3-S5 dermatome
    perianal region
  16. S2-S5 dermatome
    Saddle Region
  17. L4 dermatome
    Medial foot
  18. L5 dermatome
    Top of foot
  19. S1 dermatome
    Lateral foot
  20. myotome
    group of muscles innervated by a single spinal nerve
  21. C5-T1 myotome
    upper extremeties
  22. L2-S2 myotome
    lower extremeties
  23. Sympathetic spinal pathways
    • Preganglionic sympathetic fibers (myelinated) through the ventral root --> spinal nerve --> white communicating ramus --> sympathetic ganglion

    Postganglionic sympathetic fibers --> ganglion --> gray communicating ramus
  24. Motor Nerves
    • large diameter
    • myelinated
  25. Pain Neurons
    • Small diameter
    • Unmyelinated/lightly myelinated
  26. Touch Neurons
    • Inbetween diameter to large diameter
    • myelinated
  27. Visceral neurons
    • Small diameter
    • unmyelinated/lightly myelinated
  28. Lower motor neuron
    -neuron with a cell body in the brain stem or spinal cord and an axon that synpases on a striated muscle
  29. LMN syndrome
    • -weakness
    • -hypotonia
    • -hyporeflexive
    • -maybe atrophy
    • -fasciculations
  30. Peripheral Neuropathy
    • -motor loss
    • -can include sensory loss

    polyneuropathy: symmetrical, stocking pattern
  31. NMJ Disorders
    • -only weakness
    • -tend to be diffuse
    • -very rare
  32. Myopathies
    • -weakness only
    • -diffuse and symmetrical
    • -mostly proximal
  33. Stretch Reflex
    • -keep muscle at a constant LENGTH
    • -somatosensory organ in muscle spindle stimulated with stretch --> Ia afferents to spinal cord --> ventral horn (anterior horn cells)
    • --> contraction of the muscle

    -spinal cord wired at stronger level than needed, dampened by brain

  34. Golgi Tendon Organ Reflex
    • -keep muscle at a constant TENSION
    • -glycinergic inhibitory interneuron included
    • -uncommonly seen in everyday life, can be seen in spastic patients
  35. Reciprocal Innervation
    • -if you contract a muscle you relax the antagonists
    • -uses the same glycinergic interneuron pool
  36. Flexion withdrawal reflex
    • -can be consciously overridden
    • -step on pin, lower extremity pulls up with flexion at all joints
    • -hard wired into spinal cord to a stronger degree than needed
  37. Descending extrapyramidal pathways
    • -motor pathways that have cell bodies in the brain stem that project caudally to innervate LMNs
    • -none of these cell bodies are in the cerebral cortex --> all are under REFLEX control
    • -none travel through the pyramid of the medulla

    -provides the unconscious framework upon which the cortical and descending pyramidal system executes conscious voluntary movements
  38. Cortical and descending pyramidal system (UMN)
    • -primary motor cortex (precentral gyrus)
    • -corona radiata
    • -posterior limb of internal capsule
    • -ventral midbrain
    • -basis pontis
    • -cross in pyramidal decussation
    • -become lateral corticospinal tract
  39. Corticobulbar
    UMN that leaves the pyramidal tract in the brain stem to innervate a brain stem motor nucleus
  40. Corticospinal
    UMN reaches the spinal cord and innervates an anterior horn cell
  41. UMN syndrome
    • -weakness in a characteristic pattern (upper extremeties: extensors > flexors, lower extremeties: flexors > extensors)
    • -spasticity
    • -hyperreflexive
    • -Babinski sign

    ***acutely associated with decreased muscle tone and decreased reflexes
  42. Diazepam
    • GABAA receptor agonist
    • -anti-spasticity effect
    • -decreases activity of some descending extrapyramidal pathways
    • -adverse effect: CNS depression
  43. Baclofen
    • -acts on GABAB receptors
    • -presynaptic effect on the UMN
    • -adverse effect: CNS depression
  44. Tizanidine
    • -alpha 2 receptor agonist
    • -presynaptic effect
    • -Adverse Effects: hypotension, drowsiness, dry mouth
  45. Dantrolene
    • -acts directly on skeletal muscle
    • -Adverse effects: hepatotoxicity
    • -most often used to tx: neuroleptic malignant syndrome and malignant hyperthermia
  46. Cyclobenzaprine
    • -skeletal muscle relaxant
    • -may only be secondary to sedation