Upper Motor Neuron Control of the Brainstem and Spinal Cord

6 important questions on Upper Motor Neuron Control of the Brainstem and Spinal Cord

Where do most upper neurons from the brainstem terminate? From that, what can you tell about their function?

Most upper motor neurons from the brainstem terminate in the medial part of the ventral horn. This suggest that these upper motor neurons are responsible for posture control and balance, since they innervate the muscles associated with.

Where do upper motor neurons from the cortex terminate primarily? What function derives from this fact?

Upper motor neurons from the cortex terminate primarily in the lateral part of the ventral horn. This means that these upper motor neurons are considered with precise and skilled movements.

Why are the superior facial muscles rarely affected by lesions (or stroke)?

Because the superior muscles are innervated by by upper motor neurons arising from the cingulate motor area. So it could be possible that following a stroke the inferior facial muscles are paralyzed because of a lesion in the primary motor cortex, while the superior facial muscles are spared.
The upper motor neurons arising from the cingulate motor cortex also bifurcate bilaterally, so a lesion of one tract does not necessarilly mean that the superior facial muscles are affected (Box 17b)
  • Higher grades + faster learning
  • Never study anything twice
  • 100% sure, 100% understanding
Discover Study Smart

What does the motor map represent? Is it a map consisting of individual muscles or are movement encoded?

The motor map is organised around relevant movements. For example one site of the motor map might bring the arm towards the midline (for inspecting objects) and stimulation of an area more lateral elicits a movement bringing the arm towards the mouth.

What is a possible explanation for hypotonia (decease of muscle tonus)?

Damage to the Ia-afferents, so the afferents no longer give information about the alpha-motor neuron activity

What is a possible explanation for hypertonia (increased muscle tonus)?

Damage of upper motor neurons. The respons of alpha-motor neurons to Ia-afferent information is increased, increased gain.

The question on the page originate from the summary of the following study material:

  • A unique study and practice tool
  • Never study anything twice again
  • Get the grades you hope for
  • 100% sure, 100% understanding
Remember faster, study better. Scientifically proven.
Trustpilot Logo