Lower extremity innervations (peripheral nerve and 2 roots)
Quadriceps
Femoral; L2-L4
Adductor longus
Obturator (L2-L4)
This nerve can cause problems for patients with a large pannus or a tight belt
Lateral femoral cutaneous nerve (L2, L3)
Stim behind medial malleolus; G1 over abductor hallucis
Tibial motor
A motor unit action potential with this many (or more) phases is considered to be abnormal.
5 phases
*Polyphasicity is a measure of synchrony; the extent to which muscle fibers in a single motor unit fire at the same time
Tibialis anterior
Deep fibular nerve; L4-L5
Flexor digitorum longus
Tibial; L5-S1
The tibial and common fibular nerves give off sensory branches that ultimately form this nerve
Sural
Tibial: Medial sural cutaneous
C. Fibular: Lateral sural cutaneous
Stim at the calf just lateral to midline; G1 behind lateral malleolus
Sural (sensory)
Which measure in a NCS is representative of the fastest firing fibers in the nerve being studied?
Onset latency
Posterior tibialis
Tibial; L4-L5
Gluteus Medius (peripheral nerve and 3 nerve roots)
Superior gluteal nerve; L4, L5, S1
AFOs were made because of injuries to this nerve
Fibular (deep fibular also accepted)
G1 over tibialis anterior; G2 over anterior ankle; stim at fibular head
Peroneal motor (TA pickup)
*Better for evaluating foot drop directly
Gluteus maximus innervation (peripheral nerve and 3 roots)
Inferior gluteal nerve (L5, S1, S2)
Fibularis longus
Superficial fibular nerve; L5-S1
Fibularis tertius
Deep peroneal nerve; L5-S1
*Performs dorsiflexion/eversion
This nerve relays sensory information from the dorsum of the foot, but not the 1st web space
Superficial fibular nerve
G1 over anterior lateral ankle between TA tendon and lateral malleolus; stim lateral calf over fibula, 14 cm proximally
Superficial fibular (sensory)
It's considered normal if the drop in CMAP amplitude for a tibial motor study is < __ % from distal to proximal sites
< 50%
Short head biceps femoris (be specific about peripheral nerve; 3 nerve roots total)
Sciatic nerve (fibular division); L5-S2
Iliopsoas (1 peripheral nerve and 3 rami)
Iliacus: femoral nerve (L2-L4)
Psoas major: anterior rami L1-L3
This branch of the tibial nerve innervates most of the deep muscles of the foot as well as the skin on the 4th and 5th toes
Lateral plantar nerve (S1, S2)
G1 over soleus; G2 over Achilles tendon; stim at mid popliteal fossa with cathode pointing proximally
H-reflex
*Assesses the entire S1 reflex arc; can be used when assessing S1 radic
Which leg muscle could you needle to help differentiate an L5 radiculopathy from a common fibular neuropathy?
Posterior tibialis (tibial nerve; L4-L5)
*Only muscle with a large L5 component in the leg that is not common fibular derived.