Lecture 10

Question 1

Lower motor neuron lesions AND acute CNS lesions can cause ___________

Answer 1

Hypotonia/flaccidity

Question 2

Chronic upper motor neuron lesions will cause…

Answer 2

Hypertonia/spasticity

Question 3

The lack of inhibition of which tracts causes hypertonicity (spacticity), when impacted by an upper motor neuron lesion?

Answer 3

Reticulospinal and corticospinal

Question 4

Normal muscle rigidity : Resistance to passive mvmt is ____________ no matter how fast/slow you try to move the body part

Answer 4

Resistance to passive mvmt is constant no matter how fast/slow you try to move the body part

Question 5

Some basal ganglia disorders can cause cogwheel rigidity, which is….

Answer 5

When passive movements of a muscle trigger start-stop ratchet-like rigidity

Question 6

Gegenhalten

Answer 6

Resistance to passive stretch that remains constant no matter how fast/slow you move it

Question 7

Identify

Answer 7

Decerebrate

Remember more “E”s in the word for extension

Damage between brainstem and the midbrain/pons

Question 8

Identify

Answer 8

Decorticate

Damage to superior midbrain or severe B lesions of cortex

Question 9

Spasticity definition

Answer 9

intermittent or sustained involuntary hyperactivity of a skeletal muscle associated with an upper motor neuron lesion

Question 10

Normal progression of UMN lesion:

Answer 10

Spinal Shock (flaccidity) -> spasticity

Question 11

What are the 2 hallmarks of spasticity?

Answer 11

Increased velocity dependent muscle tone

Tendon jerk (deep tendon reflex - DTR) hyperreflexia

Question 12

Clonus definition

Answer 12

Repetitive reflex contraction of single muscle
Can be sustained or unsustained

Question 13

What is the clasp-knife phenomenon

Answer 13

an initial resistance when attempting passive movement of the extremities, followed by a rapid decrease in resistance. Indicates UMN lesion

Question 14

Biomechanical factors of spasticity

Answer 14

Changing viscoelasticity of muscle

Muscles and tendons become stiff

Reduced # of sarcomeres in proportion to reduced length in chronic stages

HIGH risk of contractures

PROM and/or AROM may still remain normal if no fixed shortening or contracture

Question 15

Weak ________ binding can contribute to spasticity

Answer 15

Actin-Myosin

Question 16

Benefits of spasticity

Answer 16

Maintain postural
Maintain muscle mass
Maintain bone mineralization
Reduce dependent edema
Prevent deep vein thromboses

Question 17

Spasticity arises when pyramidal tract is interrupted at: _____ , ______ , _______

Answer 17

Cortex
Corona radiata
Internal capsule

Question 18

What tract is inhibitory for spasticity?

Answer 18

Dorsal Reticulospinal

Question 19

What tracts are excitatory for spasticity?

Answer 19

medial reticulospinal and vestibulospinal

Note: Dorsal reticulospinal is inhibitory

Question 20

True or false: Lesions of primary motor cortex alone will produce spasticity

Answer 20

false

Question 21

Lesions must include the ____________ cortex to produce spasticity

Answer 21

pre-motor cortex

Question 22

Why do lesions of the anterior limb of the internal capsule produce spasticity?

Answer 22

Because fibers of supplementary motor cortex pass through here

Question 23

Where in the internal capsule is the corticobulbar tract found?

Answer 23

Genu

Question 24

Describe the contents of the posterior limb of the internal capsule

Answer 24

Has the Corticospinal tract inside

With the UE in the anterior portion

Trunk in the middle portion

and LE in the most posterior portion

Question 25

Where does the cortico-reticular tract arise?

Answer 25

premotor and supplementary motor areas

Question 26

Reticulospinal tract projects to __________ in SC

Answer 26

Motor neurons and interneurons

Question 27

ventromedial reticular formation is this formation excitatory or inhibitory?

Answer 27

Inhibitory

Question 28

What inhibits the spinal stretch reflex (DTR)

Answer 28

ventromedial reticular formation

Question 29

Excitatory system – diffuse/extensive areas in midbrain, pons, and bulbar medullary reticular formation These systems facilitate ______ and ___________ but they inhibit __________

Answer 29

Facilitate: Extensors (anti-gravity muscles) + DTR Inhibit: Flexors

Question 30

The lateral coritcospinal tract inhibits the __________

Answer 30

reticulospinal tract

Question 31

Excessive reticulospinal drive (lack of lateral corticospinal) can cause

Answer 31

Contracture, spasticity

Question 32

Cell bodies of gamma motor neurons are located where?

Answer 32

Ventral horn

Question 33

Increased fusiform drive from reticular formation -> hyperactivity of _______ -> Increased muscle spindle sensitivity

Answer 33

Gamma Motor Neurons

Question 34

True or false: During spinal shock you will have exxagerated Deep tendon reflexes

Answer 34

False, they will be absent

Question 35

What are examples of enhanced cutaneous reflexes due to lack of supraspinal inhibition?

Answer 35

Babinski sign Flexor Withdrawal reflex

Question 36

True or false: Spasticity can be triggered by both non-nociceptive and nociceptive input

Answer 36

True

Question 37

What will a nerve conduction velocity test show when you have spasticity?

Answer 37

Nothing because spasticity is a CNS problem but NCV tests the PNS -Bryan Yu, SPT 2024