Motor Control 1

Question 1

Name the Corticospinal tract

Answer 1

SMA/Pre-motor cortex/M1 —> corona radiata —> posterior limb of the internal capsule —> crus cerebri —> basilar pons —> pyramids
Fibers that cross the pyramidal deccusations become the lateral Corticospinal tract
Fibers that do not cross become the anterior Corticospinal tract

Question 2

Tectospinal tract

Answer 2

Superior colliculus —> crosses midline in midbrain —> terminates in cervical spinal cord
Coordination of head, neck, eyes

Question 3

Medial vestibulospinal tract

Answer 3

Medial vestibular nucleus —> descends bilaterally to cervical spine and upper thoracic through medial longitudinal fasiculus —> terminates on interneurons and propriospinal neurons in ventral horn
Head stabilization

Question 4

Lateral vestibulospinal tract

Answer 4

Lateral vestibular nucleus —> descends ipsilaterally through the anterior funiculus —> rostral fibers go to cervical, middle fibers go to thoracic, caudal fibers go to lumbar
Excite motor neurons that innervate paravertebral and proximal limb extensors

Question 5

Reticulospinal tract

Answer 5

Pain modulating and visceromotor roles

Maintenance of posture and modulation of muscle tone

Question 6

Pontine (medial) reticulospinal tract

Answer 6

Descends ipsilaterally to all spinal levels
Terminates on interneurons
Excitatory

Question 7

Medullary (lateral) reticulospinal tract

Answer 7

Depends bilaterally

Inhibitory

Question 8

What is Weber Syndrome?

Answer 8

Hemorrhage of the midbrain that results in contralateral hemiparesis of the arm and leg and deviation of the ipsilateral eye down and laterally due to damage to ipsilateral oculomotor nerve

Question 9

What is superior alternating hemiplegia?

Answer 9

Cranial nerve on one side and Corticospinal signs on the other side

Question 10

What is inferior alternating hemiplegia?

Answer 10

Contralateral hemiparesis (usually with spasticity) and ipsilateral flaccid paralysis of tongue (goes toward side of lesion)
Since medial lemniscus has already crossed, likely loss of two point discrimination and vibratory sense

Question 11

Does the tectospinal tract cross?

Answer 11

Yes, right away in the midbrain

Question 12

Where does the somatomotor role for the reticulospinal tract originate?

Answer 12

Pontine reticular nuclei or the giantocellular reticular nucleus in the medulla

Question 13

Rubrospinal Tract

Answer 13

Neurons in red nucleus (midbrain) give rise to axons —> cross midline in anterior tegmental deccusation —> descend through brainstem to spinal cord anteriorly
Excitatory to motor neurons of proximal limb flexors in UE only

Question 14

What structures does the rubrospinal tract have connections linking?

Answer 14

Cerebellar nuclei, inferior olive, red nucleus

Question 15

Negative signs of lesions in motor structures in CNS

Answer 15

Motor deficits due to loss of function

Weakness, loss of dexterity, fatigue

Question 16

Positive signs of lesions in motor structures in CNS

Answer 16

• excess of neural activity
• something added to a movement that leads to dysfunction, or increased energy expenditure
• hypertonia, hyperreflexia, spasticity, dyskinesias
• PTs can treat

Question 17

Lesions in SMA produce

Answer 17

Apraxia

Question 18

Are flexor or extensor interneurons excitatory?

Answer 18

Flexor: excitatory
Extensors: inhibitory

Question 19

Decerebrate Rigidity

Answer 19

• brainstem transected between superior and inferior colliculus
• leads to unopposed hyperactivity in extensor mm
• all descending cortical systems are disrupted
• reticulospinal projections intact but nonfunctional

Question 20

Decorticate Rigidity

Answer 20

• transection of brainstem at level rostral to superior colliculus
• rubrospinal UE flexion remains intact
• can progress to decerebrate posturing