Spinal cord descending tracts

Descending tracts

The descending tracts are the pathway by which motor signal are sent from the higher centers to the lower motor neurons.

The lower motor neurons are responsible for the movement in the muscles of the periphery.

Descending tracts are divided into two groups-

  1. Pyramidal tracts
  2. Extra-pyramidal tracts


Pyramidal tracts-

These tracts originate from the cerebral cortex  carrying motor fibers to the spinal cord and brain stem.
  • These tracts are responsible for the voluntary movements of the body and the face.
  • These tracts have their name from the medullary pyramids of the medulla oblongata through which they passes.
  • These tracts are divided into two groups-
  1. Corticospinal tracts
  2. corticobulbar tracts
Corticospinal tracts are the descending tracts which carry the motor impulses from the cerebral cortex to the spinal cord  for the movement of the body.

Corticobulbar tracts are the descending tracts which carry the motor fibers for the movement of the head and the neck. 


Extra-pyramidal tracts-

These are the descending tracts originate form the brainstem and are responsible for the autonomic and the involuntary movement of the body such as the muscles tone, balance, posture and the locomotion.
  • These tracts are divided into four groups-
  1. vestibulospinal tracts
  2. reticulospinal tracts
  3. rubrospinal tracts
  4. tectospinal tracts

Vestibulospinal tracts

These are the pathways medial and the lateral. These fibers arises from the vestibula nuclei which receives the input form the organs of the balance that is ear.
fibers in this pathway control balance and the posture through lower motor neurons.

Reticulospinal tracts

These are the descending tracts that arises from the pons and the medulla oblongata.
fibers from the pons facilitates the voluntary movements and increase muscles tone.
fibers form the medulla oblongata inhibits the voluntary movements and reduces the muscles tone.

Rubrospinal tracts

These are the fibers which arises form the red nuclei of the midbrain and crosses to other side of the body in case of the emergency and are responsible for the fine movements of the hands.

Tectospinal tracts

Tectospinal tracts arises from the superior colliculus of the midbrain.
These fibers have the functions in controlling the movement of the head while with the vision stimuli.


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