Clinical aspect of pyramidal tract

The pyramidal  system is that system represented by the corticospinal tracts. The term pyramidal is taken form the pyramids of the medulla. This system takes charge of voluntary activities in the body, that is those actions that are meditated and performed by will as opposed to those actions, which are autonomous and controlled by the autonomic nervous system.

The pyramidal system or tract therefore runs from the cerebral cortex from motor area in the frontal lobe to the lower levels of the neuraxis mainly at the spinal cord but also at the cranial nerves that control willful activities, eg eye movement by oculomotor and tongue movement by the hypoglossal nerve. The corticospinal tract descends into the spinal cord and synapses with motor nerves from the nucleus motorius lateralis and medialis. The second order neurons now issue from these synapses to reach the end plate or effector organs. They are called the following names

Upper motor neuron- this is the first order neuron. They arise from the cortex and synapse at lower levels in the brain or spinal cord.

When damaged they have features which are different form those of lower motor neurons. They are as follows

Hypereflexia

  • Hypertonicity of muscles

  • Positive Babinski sign or Extensor plantar response

  • Positive pathological reflexes (others) e.g. Rossolimo

  • Absence of superficial abdominal reflexes

  • Spastic paralysis

Lower motor neuron lesion

  • Flaccid paralysis

  • Hypotonia

  • Absence of Babinski and other pathological reflexes

  • Presence of superficial abdominal reflexes

 

 

 

 

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