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Muscle and Periph Nerve Path
15.3.07
41
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Not Applicable
03/17/2007

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Term
define descending structure of muscles;
Definition
brachioradialis muscle: bundle of muscle fibers: muscle fiber with motor neuron: nuclei, mitochon of myofibrils: sacromeres: actin and myosin
Term
Key features of normal muscle
Definition
1. all nuclei at periphery
2. internal structure of fibers is regular
3. no appreciable connective tissue (collagen) btwn fibers "endomysium"
Term
STATE 3 different motor neuron types
Definition
Type 1 fibers; type 11A fibers; type IIB fibers
Term
Type I fiber
Definition
low twitch, require O2, sustained muscle control, rich in mitochondria
Term
type IIA
Definition
fast; glycolytic; rich in glycogen
Term
Typew IIB:
Definition
fast glycolytic; oxidative
Term
Are motor neuron types segregated or integrated?
Definition
intergrated
Term
Name histopath changes of muscle finers in muscle diseases. READ
Definition
1. neurogenic atrophy
2. muscle fiber degen (necrosis) and regen
3. cytoarchitect changes and inclusions in MFs
4. atrophy
5. vasculitis
6. end-stage muscle with atrophy, fibrosis, and fatty replacement
7. Neoplasms
Term
How are muscle fibers reinnvervated?
Definition
damage 1 nerve, reiinveration by collateral sprouts from remaining axon which induces regrowth of muscle fibers and alteration in muscle fiber type, leading to fiber type grouping.
Term
what does reinnveration allow for?
Definition
It allos for the type of muscle fiber to be changed--which may lead to different function. This all leads to progressive loss of muscle function
Term
What is the hallmark of initial destructive myopathy?
Definition
Pallor
Term
Order: necrosis, basophilic regenerating fiber, macrophage invasion and regen of myoblasts; fusion of myoblasts.
Definition
necrosis, macrophage invasion and regen of myoblasts; fusion of myoblasts; basophilic regenerating fiber.
Term
what are inflammatory myopathies characterized by?
Definition
muscle fiber degen (necrosis) and regeneration AND inflammation (perivascular, perimysial, and endomysial)
Term
What distinguishes inflamm myopathies from other types of myopathies (such as muscular dystrophies)?
Definition
the presence of perivascular, perimysial, or endomysial inflammation along with the pattern of muscle fiber atrophy
Term
What are 3 major inflammatory myopathies?
Definition
1. polymyositis

2. dermatomyositis

3. inclusion body myositis
Term
Describe who gets polymyositis.
Definition
adult females
Term
what muscles are affected in polymyositis?
Definition
symmetrical, proximal
Term
are serum CK levels depressed in polymyositis?
Definition
No--elevated up to 50X
Term
what is the pathology of polymyositis?
Definition
CD8+ T cell mediated
Term
in polymyositis, where is the inflammation directed?
Definition
at the muscle fibers, with active invasion by inflammatory cells.
Term
In polymyositis, where is the distribution of inflammation?
Definition
perivascular, endomysial, perimysial
Term
What age do you get dermatomyositis?
Definition
any age, but 2 peaks in childhood and in adults
Term
do male or females get dermatomyositis?
Definition
females (2:1)
Term
What is distinguishing feature of dermatomyositis?
Definition
RASH
Term
What type of atrophy in dermatomyositis?
Definition
Perifascicular atrophy
Term
What is the pathogenesis of dermatomyositis?
Definition
B-cell AB mediated vascular disorder
Term
What types of rashes found in dermatomyositis?
Definition
1. rash on extensor surfaces on extremities,
2. Heliotrophic rash,
3. Gottron's nodules on knuckles
Term
Tx for dermatomyositis?
Definition
immunosuppresion (steroids), azathioprine, methotrexate.
Term
What is inflammed in dermatomyositis?
Definition
the capillaries, NOT the myofibers
Term
dermatomyositis is predom what type of disease?
Definition
a vasculitis
Term
Are myofibersl generally affected by dermatomyositis
Definition
no
Term
What gets deposited around capillaries in dermatomyositis?
Definition
Compliment deposition (C5b-9) around capillaries
Term
Who gets Inclusion Body Myositis?
Definition
Old men
Term
Which muscles are affected in Inclusion Body Myositis?
Definition
distal extensor muscles
Term
What are the distinguishing features of Inclusion Body Myositis?
Definition
you get inclusion bodies in muscle fibers that have rimmed vacuoles.
Term
What fills the rimmed vacuoles in Inclusion Body Myositis?
Definition
filamentous material or tubulovescular material
Term
What are 2 pathological finding of Inclusion Body Myositis?
Definition
1. endomysial inflammation
2. focal invasion of muscle fiber by inflammatory cells
Term
Who gets Duchenne muscular dystrophy?
Definition
Young boys
Term
What are the common features of Duchenne muscular dystrophy?
Definition
1. prox. progressive weakness
2. pseudohypertrophy
3. elevated CK levels.
Term
Is there a total absence of dystrophin in Becker's muscular Dystrophy?
Definition
No. Only in Duchenne muscular dystrophy.
Term
What are the 2 path hall mark features of Duchenne muscular dystrophy?
Definition
1. necrotic muscle fibers
2. phagocytosis (and invasion of fibers by macrophages)
3. Fibrosis -->pseudohypertrophy
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