Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
|
What does a motor unit consist of?
|
LMN (anterior horn or cranial nerve nucleus)
Axon Innervated muscle fibers |
|
|
What is the role of Schwann cells?
|
Provide myelin for the PNS - myelin composed of 2 layers of fused Schwann cell membrane
Death of axon results in myelin breakdown but Schwann cell remains viable (if myelin is lost axon is not disrupted) |
|
|
What is the epineurium?
|
Loose connective tissue binding fascicles into single nerve trunk, contains majority of vascular supply
|
|
|
What is the perineurium?
|
Connective tissue that is circularly arranged around each fascicle & contains tight junctions restricting entry of foreign material into endoneurium - blood nerve barrier
|
|
|
What is the endoneurium?
|
Interstitial connective tissue w/in fascicles & outside the axon-Schwann cell units
|
|
|
What kind of technique should be used to identify axonal degeneration vs. sedmental demyelination in long lengths of nerve fibers?
|
Teased fiber preparation
|
|
|
What is a neuronopathy or axonopathy?
|
Generalized abnormality affecting neuronal cell body or axon which manifests as dying back of distal portion of axon (example: motor neuron disease)
|
|
|
What is chromatolysis?
|
Swelling of neuron cell body w/ peripheral displacement of nucleus & Nissl substance
Occurs with direct axonal injury close to neuron |
|
|
What is Wallerian degeneration?
|
Results when axonal injury occurs because of a focal lesion such as trauma (commonly transection)
Distal portion of fiber (axon & myelin) undergoes degeneration |
|
|
What are myelin ovoids or digestion chambers?
|
Occur in either Wallerian degeneraton or a neuronopathy/axonopathy
Axon & myelin break down, Schwann cells proliferate & catabolize myelin |
|
|
What is segmental demyelination?
|
Occurs with primary dysfunction/damage of Schwann cells or primary damage to myelin sheath, but NO primary abnormality of axon
Causes conduction block or marked slowing but NO chromatolysis Schwann cells replaced & axons remyelinated |
|
|
What are the consequences of segmental demyelination over time?
|
With sequential demyelination & remyelination Schwann cell processes accumulate & form concentric circles of cytoplasm & basement membrane known as onion bulbs
|
|
|
følge (fulgte, fulgt)
|
follow
|
|
|
What is the clinical presentation of Guillan-Barre syndrome?
|
Progression over hours to days of symmetric weakness & areflexia
May extend to involve face, bulbar, respiratory muscle Most often presents as ascending paralysis, prominent sensory loss is rare |
|
|
What is chronic demyelinating polyneuritis?
|
Resembles GBS but has less acute presentation & recovery & recurs frequently
|
|
|
What is the clinical pattern of vasculitic neuropathy?
|
May see distal symmetric sensorimotor polyneuritis (common pattern for lupus) or mononeuropathy multiplex (common pattern for polyarteritis nodosa)
|
|
|
What is the most common treatable neuropathy in the world?
|
Leprosy
|
|
|
What are some peripheral neuropathies accompanying inherited metabolic disorders?
|
Adrenoleukodystrophy
Familial amyloid polyneuropathies Porphyria Refsum disease |
|
|
What is the most common hereditary peripheral neuropathy?
|
Hereditary motor & sensory neuropathy I (Charcot-Marie-Tooth, hypertrophic form or Peroneal Muscular Atrophy)
|
|
|
What is the most common sarcoma of adulthood?
|
Liposarcoma
|
