Other Motor Pathway 2

Question 1

Describe the pontine ( medial) reticulospinal tract

Answer 1

• Arise from the pontine reticular nucleus and receives bilateral cortical input through the corticoreticular fibers.
• Descends to the ipsilateral side of the spinal cord

•They also receive projections through the
spinoreticular tract

• Principal effect on axial and limb extensor muscles
• Communicates with the gamma motor neurons in the spinal cord.

Question 2

What is the route and function of the spinoreticular tract?

Answer 2

Route:
This sensory pathway is formed by collateral branches from axons running in the anterolateral system. These collaterals end in the reticular nuclei in pons and medulla.

Functions:
This tract relays sensory information to reticular nuclei about pain, temperature and crude touch in the trunk and limbs on the contralateral side. It exerts an excitatory influence predominantly on the pontine reticular nuclei responsible for facilitating contraction of the extensor muscles of the limb and trunk.

Question 3

What is the lateral vestibulospinal tract?

Answer 3

• Arise from the lateral vestibular nucleus
• Input form the inner ear and cerebellum
• Descends uncrossed to all levels of the spinal cord
• Synapse with the alpha motor neurons of the axial and limb extensor (anti-gravity muscles) thus regulating balance -related muscular responses.

Question 4

Describe the medial vestibulospinal tract

Answer 4

• Arises from the medial vestibular nucleus. •Input form the inner ear and cerebellum
• Axons descend ipsilaterally in the spinal cord as the caudal extension of the MLF
• Synapses on alpha motor neurons in the cervical and upper thoracic levels
• Muscular contraction of neck in coordination with eye movement.