Motor Systems Flashcards

1
Q

What are the pathways descending from the brain?

A

Corticobulbar and corticospinal

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2
Q

What are the clinical features of an injury to corticospinal fibers in the internal capsule?

A

corticospinal = posterior limb of internal capsule

Contralateral hemiparesis
Various CN signs

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3
Q

What is the main clinical feature of an injury to corticospinal fibers rostral to the decussation of pyramids?

A

Contralateral hemiplegia

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4
Q

What is the main clinical feature of an injury to corticospinal fibers in the decussation of pyramids with a lesion in the rostral pons?

A

Bilateral paresis of upper limbs

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5
Q

What is the main clinical feature of an injury to corticospinal fibers in the decussation of pyramids with a lesion in the caudal pons?

A

Bilateral paresis of lower limbs

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6
Q

What are the clinical features of a unilateral cervical spinal cord injury to corticospinal fibers?

A

Ipsilateral hemiplegia of upper and lower extremities

Features of UMN lesion

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7
Q

What is the clinical feature of bilateral damage to the cervical spinal cord above C4 or C5?

A

Quadriplegia

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8
Q

What is the clinical feature of unilateral injury to the thoracic spinal cord to corticospinal fibers?

A

Ipsilateral monoplegia of lower extremity

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9
Q

What is the clinical feature of bilateral injury to the thoracic spinal cord to corticospinal fibers?

A

Paraplegia

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10
Q

What do corticobulbar fibers control?

Where do they originate?

A
Cranial nerve motor nuclei
Frontal eye fields (A6 & 8) - caudal anterior limb of internal capsule
Precentral gyrus (A4) - genu of internal capsule
Postcentral gyrus (A3, 1, 2) - rostral posterior limb of internal capsule
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11
Q

What cranial nerves are not innervated bilaterally by corticobulbar fibers?
How are they innervated?

A

CN VII - contralateral for lower quadrants of face
Motor nucleus of CN XII - contralateral to tongue
CN XI - ipsilateral for SCM and trapezius

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12
Q

How would an UMN lesion to CN XII present?

A

Tongue deviated away from affected side

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13
Q

How would an UMN lesion to CN XI present?

A

Inability to turn head away from affected side or raise shoulder on affected side

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14
Q

How would an UMN lesion to CN X present?

A

Uvula deviated towards affected side

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15
Q

How would an UMN lesion to CN VII present?

A

Supranuclear palsy

Loss of voluntary control to lower half of opposite side of face (compensation for upper half)

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16
Q
Tectospinal Tract:
What is the origin?
Where is the decussation?
Where is the termination?
What is the function?
A

Superior colliculus
Dorsal tegmental decussation
Cervical spinal cord - laminae VI, VII (VIII)
Unknown, maybe posture

17
Q
Medial Reticulospinal Tract:
What is the origin?
Where is the decussation?
Where is the termination?
What is the function?
A

Pons - nucleus reticularis pontis oralis and caudalis
None
All levels of spinal cord - laminae VIII (VII, IX)
Facilitate voluntary or cortically-induced movements - increase muscle tone and action on gamma motor neurons

18
Q
Lateral Reticulospinal Tract:
What is the origin?
Where is the decussation?
Where is the termination?
What is the function?
A

Medulla - nucleus reticluaris gigantocellularis
Medulla - partial decussation
All levels of spinal cord - laminae VII (VI, VIII, IX)
Inhibit voluntary or cortically-induced movements - decrease muscle tone and action on gamma motor neurons

19
Q
Rubrospinal Tract:
What is the origin?
Where is the decussation?
Where is the termination?
What is the function?
A

Caudal magnicellular part of red nucleus
Midbrain - ventral tegmental decussation
Cervical cord - laminae V to VIII
Facilitate motor neurons innervating flexor muscles

20
Q
Lateral Vestibulospinal Tract:
What is the origin?
Where is the decussation?
Where is the termination?
What is the function?
A

Lateral vestibular nucleus of medulla
None
All levels of spinal cord - laminae VII, VIII
Facilitate alpha and gamma motor neurons innervating extensor muscles
Posture - action of vestibular apparatus or cerebellum

21
Q
Decerebrate Rigidity:
Where is the damage?
What is damaged?
What is intact?
What are the symptoms?
A

Brain and midbrain areas - cortical control of medial reticulospinal and vestibulospinal tracts
Medial reticulospinal and lateral vestibulospinal tracts
Extensor posturing (all limbs extended), jaws clenched, neck retracted

22
Q
Decorticate Rigidity:
Where is the damage?
What is damaged?
What is intact?
What are the symptoms?
A

Brain above midbrain - cortical control of rubrospinal tract
Flexor posturing (arms flexed and adducted)
Legs extended