7/27/2019 Robbins Ch. 27 Peripheral Nerve and Skeletal Muscle Review Questions

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1. Motor unit consists of what 3 parts? lower motor

neuron, axon,

muscle fiber

2. 3 major connective tissue components

of peripheral nerve are what?

epineurium,

perineurium,

endoneurium

(KNOW

THESE!)

3. What happens in segmental

demyelination?

disease affecting

Schwann cells

leading to loss of

myelin

4. What happens in axonal

degeneration?

destruction of

axon with

secondary

disintegration of

myelin sheath

5. When does denervation atrophyoccur?

skeletal muscleatrophy

6. Primary abnormality of the muscle

fiber itself is what?

myopathy

7. What is Wallerian degeneration? axonal injury

occurring as a

result of focal

lesion affecting

distal portion

8. What determines the type of muscle

(fast/slow)?

motor neuron

9. When do you see type 2 atrophy? associated with

inactivity or

disuse or during

therapy with

steroids

10. Disease characterized by weakness

beginning in distal limbs, which

advanced to proximal muscle

function?

Guillain-Barre

Syndrome

11.What cells are involved in leprosy? Schwann cells

12.What types of fibers are involved in

Leprosy?

pain fibers

13. In Charcot-Marie-Tooth disease

(HMSN I), demyelinating type, usually

presents in childhood or early

adulthood. Where is muscle weakness

seen?

below the knee

14. Type III HMSN, what parts of the body

are effected?

trunk and limb

muscles

15. The most common peripheral

neuropathy in type II diabetes

involves what types of nerves?

distal sensory

and motor nerves

16. Thiamine

deficiency is

associated

with axonal

neuropathy. A

clinical

conditiontermed what?

neuropathic beriberi

17.Axonal

neuropathies

also occur with

deficiencies of

what vitamins?

Vitamins B12, B6, & E

18.When do

avulsions

occur?

when tension is applied to peripheral nerve

19.All forms of

spinalmuscular

atrophy are

associated

with mutations

affecting what?

survival motor neuron I

20. This feature

distinguishes

dystrophies

from

myopathies?

Histologically, in advanced cases

muscle fibers undergo degeneration

and are replaced by fibrofatty tissue

and collagen.

21.What happens

in a dystrophy?

muscle fibers undergo degeneration

and are replaced by fibro-fatty tissueand collagen

22. DIFFERENCE

BETWEEN

DYSTROPHIES

AND

MYOPATHIES

- Muscular dystrophies: are a

heterogeneous group of inherited disorders

of muscle, often beginning in childhood,

that lead to progressive weakness and

muscle wasting. Histologically, in

advanced cases muscle fibers undergo

degeneration and are replaced by fibrofatty

tissue and collagen.

- Myopathies: are pathologic processes

seen in skeletal muscle due to a primary

abnormality of the muscle fiber itself.

23. 2 most

common forms

of muscular

dystrophy?

- Duchenne's Muscular Dystrophy (DMD)

- Becker's Muscular Dystrophy (BMD)

24.What is the

protein

effected in

muscular

dystrophies?

dsytrophin

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7/27/2019 Robbins Ch. 27 Peripheral Nerve and Skeletal Muscle Review Questions

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25.What does

dystrophin do?

forms interface between intracellular

contractile apparatus and extracellular

connective tissue matrix; l inks outside the

cell to inside the cell

26.What happens

clinically in

myotonic

dystrophy?

stiffness, difficulty releasing grip,;

myotonia (sustained involuntary

contraction)

27. Lipid

Myopathies:

Abnormalities of carnitine transport or

deficiencies of the mitochondrial

dehydrogenase enzyme systems can lead

to blocks in fatty acid oxidation and

accumulation of lipid droplets within

muscle (lipid myopathies). Patients with

these disorders develop muscle pain,

tightness, and myoglobinuria following

prolonged exercise or exercise during

fasting states. Fatty acids provide energy

for muscle contraction, especially when

glycogen stores are depleted (as in

fasting). With a metabolic block in fatty

acid oxidation, the required energy is not

available, resulting in symptoms.

Concomitant cardiomyopathies and fatty

liver may also occur.

28.What are the 3

subgroups of

inflammatory

muscle disease?

infectious, non-infectious, and systemic

29. Grotton lesions

are associated

with whatdisease?

>> What are

Grotton lesions?

dermatomyositis

>> scaling erythematous eruption or

dusky red patches over the knuckles,elbows, and knees

30. >> What is

dermatomyositis?

an inflammatory disorder of the skin as

well as skeletal muscle. It is characterized

by a distinctive skin rash that may

accompany or precede the onset of muscle

disease. The classic rash takes the form of

a lilac or heliotrope discoloration of the

upper eyelids associated with periorbital

edema (Fig. 27-13A). It is often

accompanied by Grotton lesions. Muscle

weakness is slow in onset, bilaterally

symmetric, and often accompanied by

myalgias. It typically affects the proximal

muscles first.

31. Muscle disease in which there is

immune mediated loss of acetylcholine

receptor?

Myasthenia

gravis

32.What cancer is typically associated with

Lambert-Eaton myasthenic syndrome?

small cell

carcinoma of

the lung