Medial Descending

Question 1

Upper motor neuron is?

Answer 1

A neuron originating in a higher center (brain or brainstem) that alters activity of interneurons and lower motor neurons in the spinal cord or brainstem

-Completely within the CNS

Question 2

Medial descending pathways - Gross motor

Answer 2

Controls muscles of the trunk, shoulder and pelvic girdles and proximal limbs

• Posture and balance
• Most receive input from cortical motor areas

Question 3

What are the 5 tracts of the medial activating system?

Answer 3

• Tectospinal tract
• Anterior/medial corticospinal tract
• Medial vestibulospinal tract
• Lateral vestibulospinal tract
• Medial reticulospinal tract

Question 4

The medial activity system tracts location is?

Answer 4

Anteromedial in the spinal cord

Question 5

What is the tectospinal tract is?

Answer 5

• Originates in the superior colliculus of the midbrain tectum and ends in the upper cervical spinal cord
• Primarily influences the eyes, and muscles of the neck and shoulder girdle
• Involved in reflexive orientation of the eyes and headto an auditory or visual stimulus

Question 6

What is the anterior/medial corticospinal tract?

Answer 6

Cerebral cortex to spinal cortex
-Does not cross in the brainstem, but many neurons cross in the spinal cord or have bilateral collaterals

-This bilateral activation reduces the impact of pyramidal tract injury on trunk voluntary control

Question 7

The anterior/medial corticospinal tract assist in control of?

Answer 7

The axial and proximal limb muscles, mostly neck, shoulder and trunk

-Gross movement and preparation of postural systems for intended movement.

Question 8

What is the medial and lateral vestibulospinal tract?

Answer 8

Start in the brainstem in the vestibular nuclei
Function is balance and posture
-Maintains center of gravity over base of support

Question 9

What is the medial reticulospinal tract?

Answer 9

Receives input from many sources
Function = posture, gross limb movement, and rhythmical patterns of activity
-May activate central pattern generator especially for gait

Question 10

Nonspecific upper motor neurons

Answer 10

Brainstem to spinal cord

• Very important in control of nociception
• Modulates activity of lower motor neurons for both voluntary and autonomic functions
• Activity increases with strong emotions (ex: anxiety)