Short Axis (SAX) proximal to the radiocarpal joint and pronator quadratus muscle, with a  measured cross-sectional area of the nerve.

carpal tunnel at radial carpal joint
Figure 11. Probe Position for axial scanning of the median nerve at the radial carpal joint and corresponding ultrasound image showing measured cross-section of the median nerve.

SAX at the level of the lunate.  Measuring the cross-sectional area of the nerve at this location.

median nerve at the level of the lunate
Figure 12. Probe position for axial scanning of the median nerve at the carpal tunnel at the level of the lunate and corresponding ultrasound image showing crosssection of normal and abnormal median nerve.

Long-axis imaging of the median nerve through the carpal tunnel.  This imaging should continue into the palm of the hand, showing the location of the nerve in relation to the palmar arch.

long axis imaging of carpal tunnel
Figure 13. Probe Position for long-axis scanning of the median nerve at the carpal tunnel and corresponding ultrasound image showing transition of normal and abnormal median nerve.