Upper motor neurone lesion
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Upper motor neurone lesion Classification and external resources
The motor tract.
DiseasesDB	27852

An upper motor neuron lesion is a lesion of the neural pathway above the anterior horn cell or motor nuclei of the cranial nerves. This is in contrast to a lower motor neuron lesion, which affects nerve fibers traveling from the anterior horn of the spinal cord to the relevant muscle(s).

Symptoms

• Spasticity, increase in tone in the extensor muscles (lower limbs) or flexor muscles (upper limbs)
• Clasp-knife response where initial resistance to movement is followed by relaxation
• Weakness in the flexors (lower limbs) or extensors (upper limbs),^[1] but no muscle wasting
• Brisk tendon jerk reflexes
• Babinski sign positive, where the big toe is raised rather than curled downwards on stimulation of the sole of the foot

Corticospinal/pyramidal tract

These are the neural tracts which descend in the spinal cord, in the lateral columns, carrying signals for voluntary movement of skeletal muscle. These nerve fibers usually originate in the cerebral cortex, then gather in the internal capsule before crossing over to the opposite side (decussation) in the medulla oblongata and proceeding down the spinal cord to meet lower motor neurones in the anterior horn.

See also

• Upper motor neuron
• Lower motor neurone lesion

References

1. ^

External links

• http://www.med.yale.edu/caim/cnerves/cn7/cn7_13.html
• http://www.lib.mcg.edu/edu/eshuphysio/program/section8/8ch3/s8ch3_34.htm

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