Re: what are long tract signs

Long-tract signs refer to symptoms that are attributable to the 
involvemnet of the long fiber tracts in the spinal cord, which connect the 
spinal cord to the brain and mediate spinal and motor functions.  Reference 
1 states that "of the 10 or more long fiber tracts coursing longitudinally 
in the spinal cord, only three are of prime importance in clinical 
practice: 
        a.The lateral corticospinal tract contains axons from neurons in 
the motor cortex that project directly or through interneurons to motor 
neurons at the segmental levels. [These fibers mediate voluntary motor 
functions.] 
        b.Sensory fibers subserving pain and temperature (and crude touch) 
enter at each segment through the dorsal roots, synapse, and the second 
order neuron crosses to join the spinothalamic tract. 
        c.Sensory fibers subserving position, vibration and disciminative 
touch enter through the dorsal roots, and directly (without a synapse and 
without crossing) join the posterior (or dorsal) columns." [These fibers 
mediate "2-point discrimination", the ability to localize sensation on the 
body, and "conscious proprioception", which is knowing where your body is 
in space.]

Reference 2 notes that long-tract signs allow for the diagnosis of the 
location of a disease process or injury. 


REFERENCES
 http://www.medinfo.ufl.edu/year2/neuro/review/sp.html
 http://ome-web.ummed.edu/curriculum/MBB1/MBBHTML/SC/
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