Peripheral Nerves and Skeletal Muscles Flashcards
what do afferent nerves do
relaying sensation away from the body towards the CNS
what do efferent nerves do
send out commands from the CNS to the body
what does the epineurium do
enclose the entire nerve
what does the perineurium do
groups subsets of axons into fascicles
what does the endoneurium do
surrounds individual nerve fibers
what do Schwann cells do
produce myelin sheath
what are nodes of Ranvier
unmyelinated gaps
what is Wallerian degeneration
when axons degenerate over time - leads to a slow onset and reduces signal strength
what is a traumatic neuroma
pseudo tumor produced when stumps of a severed nerve begin to proliferate
which two things can cause a neuronopathy (destruction of neurons)
infections
toxins
what is Guillain-Barré syndrome
demyelinating of the peripheral nerves caused by some kind of virus
leads to ascending paralysis which can affect the respiratory system
what is the most common chronic acquired inflammatory peripheral neuropathy
chronic inflammatory demyelinating polyradiculoneuropathy
what is chronic inflammatory demyelinating polyradiculoneuropathy
condition that affects nerves and their roots
is not caused by a virus
responds to steroids
in which condition would you see an “onion bulb”
chronic inflammatory demyelinating polyradiculoneuropathy
what is an “onion bulb”
area of demyelination and remyelination seen in chronic inflammatory demyelinating polyradiculoneuropathy
what is vasculitis
noninfectious inflammation of blood vessels that can damage peripheral nerves
what is the other name for Leprosy
Hansen disease
how are nerves affected in Lyme disease
facial nerve palsies
which type of nerve is most affected in those with HIV/AIDS
peripheral
what is the Varicella-Zoster Virus (shingles)
activation of latent chickenpox virus
causes degeneration of the axons of the peripheral nerves
which two nerves are most commonly involved in the Varicella-Zoster Virus (shingles)
1.) thoracic
2.) trigeminal
what is the most common cause of peripheral neuropathy
diabetes
what are the two most common factors of diabetic peripheral neuropathy
1.) atherosclerosis of vessels
2.) destruction of peripheral nerves
20-40% of those with diabetic peripheral neuropathy can also have which four conditions of the autonomic nervous system
1.) postural hypotension
2.) difficulty emptying bladder
3.) sexual dysfunction
4.) lumbosacral radiculoplexus neuropathy
what is Myasthenia gravis
autoimmune disease associated with autoantibodies against acetylcholine receptors
causes double vision and affects the respiratory system
which gender is more affect by Myasthenia gravis
females 2:1
what additional condition is associated with Myasthenia gravis
thymic abnormalities (enlarged)
what is Lambert-Eaton Myasthenic Syndrome
autoimmune disorder where antibodies block acetylcholine release by inhibiting a presynaptic calcium channel
50% of those with Lamber-Eaton Myasthenic Syndrome also have what
an underlying malignancy like small cell neuroendocrine tumor of the lung
what is Botulism
disease caused by exposure to Botox
blocks release of acetylcholine
which disease can young children get from ingesting honey
Botulism
what is the organization of the skeletal muscle from largest to smallest
muscle
fascicle
fiber
sarcolemma
myofibrils
what is a myofibril
contractile unit of muscle
what is myosin
creates thick filament contractile proteins
what is actin
creates thin filament contractile proteins
which type of muscle fiber is a slow twitch
type 1
which type of muscle fiber is a fast twitch
type 2
what is a neurogenic injury
injury that causes disruption of muscle innervation
leads to fiber atrophy, giving them a flattened, angular shape
what are the three morphologic changes of a myopathic injury
1.) segmental myofiber degeneration and regeneration
2.) myofiber hypertrophy
3.) cytoplasmic inclusions
what is dermatomyositis
autoimmune inflammatory myopathy that affects the skin and skeletal muscles
leads to discoloration of the skin, nail folds, eyelids, and gums
what is seen histologically in dermatomyositis
myofiber atrophy at the edges of the fascicles (perifascicular atrophy)
what is seen histologically in inclusion body myositis
rimmed vacuoles
what is the most common inflammatory myopathy in patients over 65 years of age
inclusion body myostitis
what is seen histologically in polymyositis
necrotic, regenerating, and atrophic myofibers in a patchy distribution
what are the three main types of inflammatory myopathies
1.) dermatomyositis
2.) inclusion body myositis
3.) polymyositis
what is the most common cause of a drug myopathy
cholesterol lowering drugs like statins
which type of toxic myopathy is seen with corticosteroid therapy
ICU myopathy (myosin deficient myopathy)
the most common muscular dystrophies are _____
X-linked
what is the most common type of muscular dystrophy
Duchenne muscular dystrophy
what is the main cause of muscular dystrophy
lack of the structural protein dystrophin
what is the second most common type of muscular dystrophy
Becker muscular dystrophy
what is myotonic dystrophy
multi system genetic disorder associated with muscle weakness, cataracts, and cardiomyopathy
where do peripheral nerve sheath tumors come from
Schwann cells
what is a schwannoma
benign tumor of the Schwann cells of the peripheral nerves
what are the three histologic hallmarks of a schwannoma
1.) Antoni A
2.) verocay bodies
3.) Antoni B
what is an Antoni A
dense eosinophilic area within a schwannoma
what is a verocay body
nuclear-free zones within a schwannoma
what is an Antoni B
hypocellular area with myxoid extracellular matrix seen in a schwannoma
schwannomas of the cranium (acoustic neuroma) most commonly affects which nerve
vestibular branch of the eighth nerve
what is a schwannoma of the cranium called
acoustic neuroma
what is a superficial cutaneous neurofibroma
small unencapsulated nodules that arise in the dermis and fat
what are diffuse neurofibromas
large, plaque like lesions of the skin
what are plexiform neurofibromas
associated with nerve roots or large nerves
resemble a bag of worms as they grow and entrap axons
what is most commonly seen histologically in a malignant peripheral nerve sheath tumor (MPNST)
arrangement of spindle cells
neurofibromatosis type 1 is caused by a genetic alteration of which chromosome
17
neurofibromatosis type 2 is caused by a genetic alteration of which chromosome
22
which three conditions are associated with neurofibromatosis type 1
1.) cafe au lait spots
2.) cutaneous neurofibromas
3.) Lisch nodules
what is a lisch nodule
melanocytic hamartoma projecting from the surface of the iris
lisch nodules are seen in which condition
neurofibromatosis type 1
which two conditions are often associated with neurofibromatosis type 2
1.) acoustic neuromas
2.) vestibular schwannomas
