G1 active recording electrode
G1: APB motor point
Place G1 over the motor point of the abductor pollicis brevis.
Table 2 · p.373 ↗
Motor study
Upper limb
Median motor nerve conduction study
Place G1 over the APB motor point and stimulate at the wrist between the FCR and PL tendons.
01 · Placement
G1, G2, stimulation and ground landmarks
G2 reference electrode
G2: distal to the first MCP joint
Place G2 distal to the first metacarpophalangeal joint.
Table 2 · p.373 ↗Stimulation site
Wrist stimulation: between FCR and PL tendons
Stimulate at the wrist between the flexor carpi radialis and palmaris longus tendons, 8 cm from G1.
Table 2 · p.373 ↗Stimulation site
Elbow stimulation: medial to the brachial artery pulse
Stimulate at the elbow medial to the brachial artery pulse.
Table 2 · p.373 ↗Ground region
Ground electrode region
AANEM places the ground between the stimulating and recording electrodes. The model shows a usable volar forearm region, not a single mandatory point.
Table 2 · p.373 ↗02 · Reference values
Adult normal limits
| Measure | Reference limit | Basis |
|---|---|---|
| Distal CMAP amplitude | ≥4.1 mV | 3rd percentile lower limit |
| Conduction velocity | ≥49 m/s | 3rd percentile lower limit |
| Distal motor latency | ≤4.5 ms | 97th percentile upper limit |
03 · Technique
Acquisition conditions
Fixed distance
G1 to wrist stimulation: 8 cm
Sensitivity
5 mV/div
Sweep
2 ms/div
Filter
2–3 Hz–10 kHz
Temperature
Maintain dorsal hand skin temperature >32°C
Ground
Place the ground between the stimulating and recording electrodes
Primary evidence
Method-matched AANEM reference data
Adult median motor reference values; see the source table for age- and sex-stratified limits.