Gazzerro - Skeletomotor system

Question 1

Name at least two ways that voluntary movement differs from reflexes.

Answer 1

• voluntary mvmt is governed by conscious planning
• it is organized around performance of a specific task
• task performance becomes more efficient w experience
• voluntary mvmt can be initiated internally w/o a sensory stimulus trigger
• sensory stimuli do not dictate the resulting mvmt, although they guide the specified task

Question 2

The motor system follows a hierarchical processing. What pathway is this called?

Answer 2

The descending lateral corticospinal pathway.

Question 3

What brain areas are involved in the planning of movement?

Answer 3

Associative cortex and the limbic system

Question 4

What is motor equivalence and what is an example?

Answer 4

-the ability to use different movements, produced by either the same or different parts of the body, to perform a task under different conditions

For example, a persons handwriting is a similar style regardless of the limb used to write. (even arm, teeth, foot, style is somewhat conserved)

Question 5

What is included in the term ‘kinematic information’?

Answer 5

-includes the position, velocity, and acceleration of the hand, joint angles and muscle length without reference to the force (muscle spindles)

Question 6

What is the primary motor cortex (M1) area 4 involved in?

Answer 6

Direction, force, and velocity of mvmt.

Question 7

What brain area is involved in the planning and anticipation of a specific motor act?

Answer 7

premotor area

Question 8

What brain area is involved in the programming of motor sequences?

Answer 8

supplementary motor area (SMA)

Question 9

The lateral corticospinal tract is involved in…

A. mostly limb control
B. proximal muscle control, mostly upper body
C. trunk control

Answer 9

A. mostly limb control

Question 10

The ventral corticospinal tract is involved in…

A. mostly limb control
B. proximal muscle control, mostly upper body
C. trunk control

Answer 10

B. proximal muscle control, mostly upper body

Question 11

The medial cortial motor path is involved in…

A. mostly limb control
B. proximal muscle control, mostly upper body
C. trunk control

Answer 11

C. trunk control

-innervation of the trunk and proximal muscles of the upper arms

Question 12

Grey and white matter development begins

A. from 20 weeks gestation
B. from birth
C. from 1 year
D. from 20 years

Answer 12

A. from 20 weeks gestation

Question 13

Cortical thickness and surface area of the brain begins to develop

A. from 20 weeks gestation
B. from birth
C. from 1 year
D. from 20 years

Answer 13

B. from birth

Question 14

Grey and white matter expansion of the brain begin postnatally.

A. true
B. false

Answer 14

A. true

Question 15

Myelin development begins prenatally.

A. true
B. false

Answer 15

B. false

-at 3 months there are very immature myelin structures
-around 3 years myelin reaches final stage
(very slow development)

Question 16

What are the 4 types of motoneurons based on functional classification?

Answer 16

alpha-FF –> fast twitch fatiguable (Type II6/x)
alpha FR –> fast twitch fatigue resistant (Type IIa)
alpha S –> slow twitch (Type I)
gamma –> intrafusal

Question 17

What are the alpha motor neurons responsible for?

Answer 17

the contraction of the muscle

Question 18

What are the gamma motor neurons responsible for?

Answer 18

the activation of the muscle spindle

Question 19

How can you differentiate between an upper and a lower motorneuron disease?

Answer 19

Upper MN: Lower MN:

• hypertonia -hypotonia
• hyperreflexia -hyporeflexia
• clonus
• atrophy -atrophy
• babinsky sign + -babinsky sign -

Question 20

What is a Babinsky sign?

Answer 20

• a reflex occurs after the sole of the foot has been firmly stroked. The big toe then moves upward or toward the top surface of the foot.
• a positive Babinski sign happens when the big toe bends up and back to the top of the foot and the other toes fan out –> may indicate damage to the CNS
• it is not normal to have a reflex stronger on one side than the other

Question 21

What are the signs of an upper motor lesion and what are some examples of conditions that involve upper motor lesions?

Answer 21

-an increase in responsiveness, no inhibitory control of motor neurons –> muscle contractions

Examples:

• ischemic or hemorragic stroke (acute presentation)
• HTLV-1 assoc Myelopathy (spastic tropical paraparesis)
• prion disease
• familiar spastic paraplegia (increased tone)
• ALS (high degree of impairment of upper MN but also an impairment of the lower MN)

Question 22

What are the signs of a lower motor lesion and what are some examples of conditions that involve upper motor lesions?

Answer 22

-decreases in tone, reflexes, and muscle mass

Examples:

• poliomyelitis and post-polio syndrome
• motor Guillain Barre syndrome
• multifocal motor neuropathy
• myopathies
• spinal muscular atrophy
• Kennedy syndrome

Question 23

Select all that are correct.
Spinal Muscular Atrophy…

A. is a disease of the upper motor neurons
B. is a disease of the lower motor neurons
C. is characterized by irreversible loss of the anterior horn cells in the spinal cord and the brain stem nuclei
D. may be caused by autosomal dominant inheritance
E. linked to autosomal recessive inheritance of 5q13.2

Answer 23

B. is a disease of the lower motor neurons
C. is characterized by irreversible loss of the anterior horn cells in the spinal cord and the brain stem nuclei
E. linked to autosomal recessive inheritance of 5q13.2

Question 24

Why does SMN1 more often lead to a functional SMN protein than SMN2?

Answer 24

• the presence of ‘c’ is critical for the splicing events of exon 7
• in SMN2 there is no ‘c’ –> instability of the splicing system. 85% of the transcript loses exon 7, leading to a non functional, truncated SMN protein. 15% remains to become a functional SMN protein

Question 25

What dictates the severity of disease in Spinal Muscular Atrophy?

Answer 25

• the level of SMN2
• additional copies are preserving muscle function
• 2 copies of SMN1 = safe
• 0 SMN1 but + 3 or 4 SMN2 = less severe disease
• 0 SMN1 + few copies of SMN2 = severe type of disease

Question 26

What are the types of mutations in SMA?

Answer 26

• deletion
• gene conversion
• point mutations (very rare)

Question 27

What is Nusinersen and what is its action in Spinal Muscular Atrophy?

Answer 27

• a drug that has been approved for spinal muscular atrophy, has been successful in treating children w the disorder (slows down the disease) –> longer life expectancy
• acts on SMN2 –> inhibits exon 7 skipping, promotes exon 7 inclusion. Leads to SMN proteins that are highly stable and functional
• must be injected into the spine

Question 28

What is Risdiplam and what is its action in Spinal Muscular Atrophy?

Answer 28

• a small molecule that modulates SMN2 alternative splicing and increases level of SMN protein
• not yet approved
• keeping the exon 7 in SMN2
• given orally

Question 29

What is Zolgensma and what is its action in Spinal Muscular Atrophy?

Answer 29

• replaces missing SMN1
• SMN gene inserted into viral vector, encapsulated in scAAV9 virus
• is injected intravenously
• has been approved for treatment of children under 2 years
• problem - may require a follow up injection over time, creates a unitary response

Question 30

What brain area is involved in the intentional control of movement?

Answer 30

the cingulate area

Question 31

What is ‘kinetic’ information?

Answer 31

is in regards to force generated (golgi tendons and mechanoreceptors in the skin)