Peripheral nerve Anatomy Flashcards
Dorsal scapular nerve target
Rhomboids
Dorsal scapular nerve roots
C4 c5
Long thoracic target
Serratus anterior
Long thoracic roots
C5 c6 C7
Long thoracic action
Stabilize shoulder when pushing
Medial pectoral roots
C8 T1
Lateral pectoral target
Pectoralis major
Lateral pectoral roots
C5 C6
Thoracodorsal target
Latissimus Dorsi
Thoracodorsal nerve roots
C6 C7 C8
Subscapular nerve target
Teres major
Suprascapular nerve target
Supraspinatus and infraspinatus
Subscapular nerve roots
C5, C6,C7
Musculocutaneous nerve targets (4)
Brachialis
Coracobrachialis
Biceps brachii
Lateral antebrachial cutaneous
Axillary nerve targets (3)
Deltoid
Teres minor
Small patch on lateral arm (sargent’s patch)
Radial nerve targets (13)
Triceps Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Supinator Extensor carpi ulnaris Extensor digitorum Extensor digiti minimi Abductor pollicis longus Extensor pollicis longus Extensor pollicis brevis Extensor indicis Superficial radial nerve
“Fat in a frying pan”
Normal spontaneous activity representing end plate spikes
Timing to abnormal spontaneous activity
2-6 weeks after injury
Abnormal spontaneous activity - represents what?
Acute lack of innervation
How long does abnormal spontaneous activity last?
Until re-innervation unless ongoing nerve injury
What causes a fibrillation potential?
AP of a single muscle fiber that loses innervation acutely or ongoing
“Ticking of a clock” represents what EMG finding?
Fibrillation potential (acute denervation)
Neuropathic causes of Fibrillation Potentials
Radiculopathies, plexopathies, peripheral neuropathies
Myopathic causes of fibrillation potentials:
Inflammation, dystrophies
Positive Sharp Waves on EMG
Acute denervation
“Raindrops on a tin roof.”
Fasciculations
What do fasciculations represent?
Random discharging of AP’s for an entire motor unit
Causes of fasciculations
ALS, benign fasciculation syndrome, axonal peripheral neuropathies
“Jackhammer” sound
Complex Repetitive Discharges (MUAP groups), non-specific
“Dive Bomber” sound
Myotonia
“Marching Soldiers”
Myokymia
Causes of myokymia
Radiation, Compression, MS
Increased MUAP Amplitude
Neurogenic - caused by simulatneous firing of fast/slow fibers
Decrease MUAP Amplitude
Myogenic - caused by decreased muscle response to stimulus *
Polyphasic MUAP’s
Neurogenic
What does increased recruitment ratio mean?
Decreased recruitment (higher frequency firing before recruiting new motor units)
What might cause decreased recruitment?
Conduction block or axonal problem
What does EMG look like in poor activation
pattern and frequency normal, few motor units
What does rapid recruitment signify on EMG
Myogenic process
Deltoid - nerve root
C5
Deltoid named nerve
Axillary
Triceps - nerve root
C7
Triceps named nerve
Radial
Biceps - nerve root
C6
Biceps - named nerve
Musculocutaneous
First dorsal interosseous - nerve root
C8
First dorsal interosseous - named nerve
Ulnar
Abductor pollicis brevis - nerve root
T1
Abductor pollicis brevis - named nerve
Median
Iliopsoas - nerve root
L2/3
Iliopsoas named nerve
Partial femoral
Vastus medialis
L4
Vastus medialis - named nerve
Femoral
Tibials anterior - nerve root
L5
Tibilais anterior - named nerve
deep peroneal
Extensor hallucis longus - nerve root
L5
Extensor hallucis longus - named nerve
Deep peroneal
Gastrocnemius - nerve root
S1
Gastrocnemius - named nerve
Tibial
Semitendinosis - nerve root
S1
Semitendinosis- named nerve
Sciatic nerve
Brachioradialis - nerve root
C6
Brachioradialis - named nerve
Radial
Extensor carpi ulnaris - nerve root
C7
Extensor carpi ulnaris - named nerve
Posterior interosseus
Extensor digitorum - nerve root
C7
Extensor digitorum - named nerve
Posterior interosseus
Abductor pollicis longus - nerve root
C7 C8
Abductor pollicis longus - named nerve
Posterior interosseus
Extensor pollicis longus - nerve root
C7
Extensor pollicis longus - named nerve
Posterior interosseus
Extensor pollicis brevis - root
C7 (C8)
Extensor pollicis brevis - named nerve
Posterior interosseus
Median nerve targets (12)
Pronator teres Flexor carpi radialis Palmaris longus Flexor digitorium superficialis Pronator quadratus Abductor pollicis brevis Flexor pollicis brevis Opponens pollicis Lumbricals 1-2 Flexor digitorium profundus 1-2 Flexor pollicis longus Sensory to anterior hand 1-3
Anterior interosseus targets
Flexor digitorum profundus (1-2)
Flexor pollicis longus
Abductor pollicis brevis - nerve root
T1
Abductor pollicis brevis - named nerve
Median
Flexor pollicis longus - nerve root
C8
Flexor pollicis longus - named nerve
Anterior interosseus
Axillary nerve roots
C5
Musculocutaneous roots
C5, C6
Radial nerve roots
C5-C8
Posterior interosseous targets
supinator extensor carpi ulnaris Extensor digitorum Abductor pollicis longus Extensor pollicis longus Extensor pollicis brevis Extensor indicis
Posterior interosseus roots
C7 (some C6 and C8)
Median nerve roots
C6-T1
Ulnar nerve roots
C8, T1
Anterior interosseus roots
C7-C8
Ulnar nerve targets
Flexor digitorum profundus (3-4) Flexor carpi ulnaris Flexor pollicis brevis Hypothenar muscles Adductor pollicis Palmar interossei Dorsal interossei Lumbricals 3-4
Femoral nerve roots
L1-L4
Obdurator nerve roots
L2-L4
Superior gluteal nerve roots
L4-S1
Inferior gluteal nerve roots
L5-S2
Sciatic nerve roots
L4-S2
Common peroneal
L5-S1 (Small L4, tib ant)
Shoulder abduction root
C5
Elbow flexion root
C5,6
Elbow extension root
C7
Radial wrist flexion root
C6
Finger extension root
C7
Finger flexion - root
C8
Finger abduction - root
T1
Hip flexion root
L1/L2
Hip adduction root
L2/L3
Hip extension root
L5,S1
Knee flexion root
S1
Knee extension root
L3/4
Ankle dorsiflexion root
L4
Ankle plantar flexion root
S1
Ankle eversion
L5/S1
Shoulder abduction - named nerve
Axillary
Elbow flexion - named nerve
Musculocutaneous
Elbow extension - named nerve
Radial
Finger extension - named nerve
Posterior interosseus
Finger flexion - named nerve
Anterior interosseus (median and ulnar help)
Finger abduction - named nerve
Ulnar nerve (some median)
Hip adduction - named nerve
Obdurator
Hip extension - named nerve
Sciatic
Knee flexion - named nerve
Sciatic
Knee extension - named nerve
Femoral
Ankle dorsiflexion - named nerve
Deep peroneal
Ankle plantar flexion - named nerve
Tibial
Ankle eversion - named nerve
Superficial peroneal
Big toe extension - named nerve
Deep peroneal
Roots responsible for lateral arm and thumb sensation
C5/C6
Roots responsible for medial arm and pinky sensation
C8,T1
Medial forearm innervation - named nerve
Musculocutaneous nerve
Anterior and lateral hand innervation - named nerve
Median
Medial hand sensory innervation - named nerve
Ulnar
Medial forearm sensory innervation - named nerve
Medial antebrachial cutaneous
Anterior lateral thigh sensory innervation - named nerve
Lateral femoral cutaneous
Anterior medial thigh, knee and medial shin innervation - named nerve
Femoral nerve
Inner thigh innervation - named nerve
Obdurator
Posterior thigh innervation - named nerve
posterior cutaneous nerve
Lateral shin and foot innervation (including webspace)- named nerve
Common peroneal
Lateral shin and foot innervation(spares webspace) - named nerve
Superficial peroneal
1-2 Toe webspace sensory - named nerve
Deep Peroneal
Lateral foot sensory - named nerve
sural nerve
Bottom of foot sensory innervation (including tips of toes)- named nerve
Tibial