Upper motor neuron lesion

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

An upper motor neuron lesion (also known as pyramidal insufficiency) is a lesion of the neural pathway above the anterior horn cell of the spinal cord 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 or the cranial motor nuclei to the relevant muscle(s).[1]

Upper motor neuron lesions occur in conditions affecting motor neurons in the brain or spinal cord such as stroke, multiple sclerosis, traumatic brain injury and cerebral palsy.


Changes in muscle performance can be broadly described as the upper motor neuron syndrome. These changes vary depending on the site and the extent of the lesion, and may include:

Corticospinal/pyramidal tract

These are the neural tracts which descend in the lateral grey columns of the spinal cord, carrying signals for voluntary movement of skeletal muscle. These nerve fibers usually originate in the primary motor cortex, pass via the corona radiata to gather in the internal capsule before crossing over to the opposite side (decussation) in the medullary pyramids and proceeding down the spinal cord to meet lower motor neurons in the anterior grey column.

See also


  1. James D. Fix (1 October 2007). Neuroanatomy. Lippincott Williams & Wilkins. pp. 120–. ISBN 978-0-7817-7245-7. Retrieved 17 November 2010.
  2. -261423104 at GPnotebook
  3. "The Precise Neurological Exam". Retrieved 2009-11-28.
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