1. The extrapyramidal tracts are descending motor pathways in the brain and spinal cord other than the corticospinal tract. They include the rubrospinal, tectospinal, reticulospinal, vestibulospinal, and olivospinal tracts. 2. The rubrospinal tract originates in the red nucleus of the midbrain and controls flexors and extensors through interneurons and motor neurons. The tectospinal tract originates in the superior colliculus and controls head and neck movements in response to visual stimuli. The reticulospinal tract has pontine and medullary components and controls extensors and flexors. 3. The

1. Descending Motor Pathways
Extra-Pyramidal or
Extra-Corticospinal Tract
Made by
Mehreen roohi

2. • All the descending tracts other than the corticospinal are included in
it.
• 1) Rubrospinal Tract:
• It arises from the red nucleus which is located in the tegmentum of
the mid-brain.
• The fibers cross over to the opposite side and than descend through
the Pons, medulla oblongata to enter the lateral white column of the
spinal cord.
• The tract fibres terminate first into the inter-neurons, which in-turn
synapse with the alpha and gamma motor neurons.

3. • Red nucleus receives fibres from the cerebral
cortex and also from the cerebellum.
• Rubrospinal tract is an accessary or alternate
pathway through which the cerebral cortex and
the cerebellum control the activity of the motor
neurons in the spinal cord.
• Rubrospinal tract is the facilitatory for the flexors
and inhibitory for the anti-gravity muscles
(extensors).

4. 2) Tectospinal Tract
• Location:
• The tract fibers arise from the superior colliculus located
in the tectum of the mid-brain.
• The tract fibers descend without crossing over and
descent through the Pons, medulla oblongata and enter
the anterior white column of the spinal cord.
• The tract fibers synapse and terminate through
interneuron onto the motor neurons in the ventral horn of
the upper cervical segments of the spinal cord.

5. • This tract controls the reflex movements of
the head and neck in response to visual
stimuli.
• For example; something shines behind the
head, so you turns your head back
through the Tectospinal tract.

7. 3) Reticulospinal Tract
• The tract arises from the reticular formation.
• Reticular formation is groups of scattered
neurons along with nerve fibers and it is present
in the mid-brain, Pons and medulla oblongata.
• Superiorly, reticular formation is connected to
cerebral cortex and inferiorly it is connected to
spinal cord.

8. Components of Reticulospinal tract
• A) Pontine component
• B) Medullary component
• Pontine Reticulospinal Tract:
• Fibres arise from the nuclei of the reticular formation of the Pons.
• These fibres remain un-crossed.
• These fibres descend to enter the anterior white column of the spinal cord.
• The tract terminate onto the motor neurons in the ventral horn of the spinal
cord, first synapse with the interneuron, which inturn synapse with the motor
neurons.
• The tract is facilitatory for the extensors and inhibitory for the flexors.

10. • B) Medullary Reticulospinal Tract:
• The tract fibres arise from the nuclei of the
reticular formation of the medulla oblongata.
• The fibres cross-over to the opposite side.
• The tract descends to enter the lateral white
column of the spinal cord.

11. • The tract fibres terminate onto the motor
neurons of the ventral horn of the spinal
cord.
• It first synapse with the interneuron which
inturn synapse with the motor neurons.
• This tract is inhibitory to the extensors.

13. 4) Vestibulospinal Tract
• Tract fibres arise from the vestibular nuclei in the
lower Pons and Medulla Oblongata.
• The tract fibres arise from the vestibular nuclei in
the lower Pons and Medulla-oblongata.
• The tract fibres after their origin mostly remain
un-crossed and than these fibres enter the
anterior white column of the spinal cord and
terminate onto the alpha and gamma motor
neurons through interneurons.

14. • This consists of two components:
• 1) Major component
• (Lateral Vestibulospinal tract)
• 2) Minor component
• (Medial Vestibulospinal tract)
• From the Lateral Vestibulospinal nuclei, there will be lateral component.
• And from the Medial Vestibulospinal nuclei, there is medial component.
• This tract is facilitatory for extensors.
• Vestibular nuclei receive fibres from cerebellum and internal ear (vestibular
apparatus).

15. 5) Olivospinal Tract
• Tract Fibres arises from the inferior olivary
nucleus located in the medulla oblongata.
• Fibres cross-over to the opposite side and than
descends into the lateral white column of the
spinal cord.
• The tract fibres terminate through interneurons
onto motor neurons of the ventral horn.

16. • This tract control the activity of the motor
neurons in the spinal cord.
• Inferior olivary nucleus receives fibres
from the cerebral cortex, corpus striatum,
reticular formation and spinal cord.