Figure 23. Guyon tunnel syndrome: ganglion. Photograph (bottom) shows the area scanned. A 30-year-old woman complained of a palpable nodule in the ulnar aspect of the wrist, with numbness of the fifth finger. Transverse US scans of the wrist show an anechoic ganglion (G) compressing the ulnar nerve (arrowheads) at wrist level. The ulnar nerve is located between the ulnar artery and ganglion.