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115 Cards in this Set
- Front
- Back
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What is a near-field volume conducted potential?
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A near-field volume conducted potential is recorded close to the action potential source and depends on the distance from the source to the electrical source (stimulus). Far-field potentials occur instantaneously and widely (stimulus artifact)
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What does a CMAP amplitude measure?
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the number of muscle fibers
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What does CMAP area measure?
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the number of muscle fibers
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What does CMAP duration measure?
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synchrony
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Why is it that peak latency cannot be used to calculate the conduction velocity?
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The population of fibers leading to peak latency is unknown, unlike onset latency which is the fastest conducting fibers
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What is an example of a mixed nerve conduction study and why is it advantageous over routine motor or ulnar studies?
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Mixed NCS are able the caputre the largest, fastest fibers, Ia fibers that supply the muscle spindle
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What would be the physiology of NCS for metachromatic leukodystrophy?
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demyelinating
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What is the physiology of NCS for Krabbe disease?
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demyelinating
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What is the physiology for neuropathy for adrenoleukodystrophY?
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demyelinating
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What is the physiology for cockayne syndrome?
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demyelinating
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What is the physiology for niemann-pick disease?
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demyelinating
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What is the physiology for cerebrotendi9nous xanthomatosis?
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demyelinating
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What toxins can cause a demyelinating neuropathy?
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arsenic, amiodarone, perhexiline, glue sniffing, buckthorn shrub poisoning
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What infection characteristically causes a demyelinating neuropathy
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Diphtheria
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What is the etiology of the axon reflex?
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The axon reflex occurs because terminal nerve division occurs more proximally then it should after nerve injury (demyelination or reinnervation). This leads to a response that travels a shorter distance than the F-wave and looks the same each time. See 4-15 p. 58 preston and shapiro
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Why is it important to wait several seconds between successive stimulations for the R2?
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The R2 habituates and you need to make sure there is electrical silence.
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What is maximal firing frequency for a motor unit?
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30 to 50 HZ
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Why is temperature so important in repetitive nerve stimulation?
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Acetylcholinesterase function decreases at cold temperature
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How long should rapid RNS be performed for?
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5- 10 seconds to see maximal increment, although some increment should be seen in the first 5 stimuli.
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Why do cool temperatures cause so many changes to NCS in the EMG lab?
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cooler temperatures result in delayed inactivation of sodium channels, prolonging depolarization time
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How much does distal latency prolong for each drop 1 degrees Celsius in temperature?
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0.2 ms per degree
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What is the action of the lumbricals?
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Extend the MCP and Flex the PIP (think of claw hand)
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What is the ligament of struthers?
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tendinous band between a humerus spur and the medial epicondyle
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What is the lacertus fibrosus?
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thick band from medial biceps tendon to proximal forearm
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Where is the anterior interosseous nerve given?
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5-8 cm distal to the medial epicondyle
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What is the sublimis bridge?
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FDS proximal aponeurotic edge
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Which pronator is most important for elbow in extension?
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pronator teres, pronator quadratus for elbow in flexion
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What is the cubital tunnel?
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it is a fibrous band that occurs between 2 heads of the FCU
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What is the conduction velocity of the C fibers (unmyelinated fibers?
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1-2 m/sec
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What is the site of entrapment that could lead to pure infraspinatus muscle weakness?
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spinoglenoid notch
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What is the waveform of EPP?
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monophasic negative spikes
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What is the usual amplitude of a fibrillation potential at 2 months?
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generally they are less than 1 mv, usually around 600 microvolts
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What is the innervation of the inferior calcaneal nerve?
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pure motor branch to ADQ minimi pedis
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What would decreasing the low frequency cutoff do to a waveform? (For example, LFF of 20 HZ to 10 HZ)?
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increase the amplitude and duration, prolong the peak latency
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What would a change to the amplifier gain (increasing or decreasing) do to a waveform?
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Increasing gain shortens the osnet latency duration, Decreasing gain prolongs the onset latency duration
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What is the fastest conduction velocity?
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alpha motor neurons at 50-120 m/sec
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What is the physiology behind pseudofacilitation?
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Better synchrony of muscle fibers without recruitment of additional fibers
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What is the anterior tarsal tunnel syndrome?
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it affects the deep peroneal nerve
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What is the arcade of frohse?
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supinator muscle site of entrapment for AIN
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What is the arcade of struthers?
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aponeurotic band from triceps to intermuscular septum, can compress the ulnar nerve
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What is the most important parameter in selecting motor units for quantitative EMG?
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rise time
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When does the biggest change happen in NCS velocity for children?
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Birth- 50%
1- 75% 3-5- 100% Biggest change is in the first 12 months |
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What are the roots for trapezius?
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spinal accessory nerve, C3-4
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What is the action of coracobrachialis?
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elevates arm with elbow flexed
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What is the action of tensor fascia lata?
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internal rotation of leg, posterior division of the sacral plexus
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What is N9 for an SSEP?
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brachial plexus
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What is N11?
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if absent, may not be abnormal.
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What is N13?
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cervical cord/dorsal columns
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What is N18?
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medial lemniscus
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What is N20?
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sensory cortex
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What is the nromal latency for a sympathetic skin response?
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1.5 seconds
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What is the insertion site for the brachioradialis?
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Midway between the biceps tendon and lateral epicondyle along flexor crease
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What is the insertion site of the pectoralis major?
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insert to the anterior axillary fold
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What is the insertion site of the serratus anterior?
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lateral to the inferior angle of the scapula
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What is the insertion site of rhomboid minor?
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one FB medial to vertebral end of scapular spine
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What is the insertion site of the latissimus dorsi?
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3 FB distal and along posterior axillary fold
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What is the action of latissimus dorsi?
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internally rotate, adduct and extend arm
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What is the insertion site of the teres major?
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3 FB above the inferior angle of the scapula
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What is the insertion site of teres minor?
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insert 1/3 of the way between the acromion and inferior angle of scpula lateral border
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What is the insertion site of biceps femoris long head?
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electrode at midpoint between fibula head and ischial tuberosity
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What is the action of gracilis?
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adduct thigh and flex the knee
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What is palmaris brevis sign?
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preserved hypothenar skin wrinkling during 5th digit abduction during a second degree ulnar neuropathy at the wrist
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What is the flick sign?
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during CTS, awakening to shake out the hand
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What are the roots/innervation for anconeus?
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C7/8 radial nerve
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What is latissimus dorsi innervation?
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C7-8, thoracodorsal nerve
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What is type 3 guyons canal?
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superficial sensory branch only
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What is the innervation of abductor hallucis?
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medial plantar branch of tibial nerve
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What is the root of FCU?
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c8-T1
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What is the generator of neuromyotonia?
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motor neuron
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What is the generator of myotonia?
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muscle fiber
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What is the action of gracilis?
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adduct thigh with knee flexed
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What is the innervation of gracilis?
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obturator nerve L2-4
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What is the insertion site of gracilis?
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half the distance from the pubic tubercle to the medial edge of the patella, superficial (1/2 inch deep)
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What is the action of biceps femoris long head?
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Flex the knee
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What is the innervation/roots of BF LH?
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Sciatic N. L5-S1
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What is the insertion site of BF LH?
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1/2 between the iscial tuberosity and fibular head
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What is the action of brachialis?
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Flex the elbow with the arm pronated
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What is the innervation of brachialis?
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mostly musculocutaneous C5-6 with some radial
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What is the insertion site of brachialis?
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Feel the biceps tendone, go 2 FB above the crease and lateral
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What is the action of coracobrachialis?
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Elevates the arm with the elbow flexed 90 degrees
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What is the innervation of coracobrachialis?
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C6-7, msuculocutaneous nerve
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What is the insertion site of coracobrachialis?
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4 FB distal to coracoid process, insert to bone and pull out
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What is the action of extensor digotrum longus?
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extend toes
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What is the innervation of extensor digitorum longus?
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peroneal nerve (common/deep) L4-5
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What is the insertion site of EDL?
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4 FB distal to TT and 2 FB lateral tibial creast through tibialis anterior
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What is the insertion site of latissimus doris?
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along posterior axillary fld, 3 FB proximal and lateral to the inferior angle of the scapula
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What is the action of latissimus dorsi?
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internally rotate and adduct the arm
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What is the innervation of latissimus dorsi?
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thoracodorsal nerve, C7-8
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What is the action of pectoralis major?
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adduct the arms
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What is the innervation of pectoralis major?
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medial and lateral pectoral nerve, medial and lateral cords, UML trunks, C5-T1
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What is the insertion site of pectoralis major?
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anterior axillary fold
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What diameter sensory axons contribute to SNAP?
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only large diameter sensory axons
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What is the innervation of hte inferior calcaneal n?
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It is a pure motor nerve that goes to ADQ pedis
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What is the aciton of rectus femoris?
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Flexes the hip and extends the knee
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What is the innervation of rectus femoris?
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femoral nerve, L2-3-4
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What is the insertion site of rectus femoris
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halfway between ASIS and superior border of patella
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What is the action of rhomboid major?
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push the palm up from small of back
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Where is the insertion site of rhomboid major?
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middle scapular spine 1 FB medial
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What is the innervatin of rhomboid major?
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dorsal scapular nerve C5
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What is the innervation of rhomboid minor?
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dorsal scapular nerve, C5
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What is the insertion iste of rhomboid minor
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vertebral scapular spine end upper 1/3, 1 FB medial
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What is the insertion site of sartorius?
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ASIS 4 FB distal along line to medial epicondyle of femoral bone
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What is the action of sartorius?
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flex hip/thigh, external rotation of thigh
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What is the innervation of sartorius?
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femoral nerve L2-3-4
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What is the action of semitendonosus?
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flex knee and internal rotation of the tibia
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What is the insertion site of semitendonosus?
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1/2 way between ischial tuberosity and medial epicondyle of patella
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What is the innervation of semitenonsus?
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sciatic nerve L5-S1-S2
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What is the action of serratus anterior?
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protract the scpular, extend arm/raise limb and push
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What is the insertion site of serratus anterior?
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lateral to inferior angle of scpula
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What i shte action of teres major?
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internally rotate humerus
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What is the innervation of teres major?
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subscapular nerve, C5-6 roots
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What is the insertion site of teres major?
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3 FB prox/lat to IA scapula
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What is the insertion site of teres minor?
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proximal 1/3 of distance between acromion and inferior angle of scapula
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What is the innervation of teres minor?
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axillary nerve, C5-6
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What is the action of teres minor?
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external rotation of humerus
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