Fig. 3

Level two extrinsic compression of the deep branch in a 61-year-old man reporting impairment in performing fine movements with the right hand. a, b Consecutive short-axis 18–5-MHz US images and c Transverse turbo Spin Echo T2-weighted MRI scan with fat saturation demonstrate a ganglion cyst (asterisk) that squeezes the deep branch (arrowhead) against the pisohamate ligament (PHL) and the hamate hook (HH). Note mild edematous changes with nerve swelling in b. The superficial branch (outlined arrowhead) is unaffected by the cyst. FT, flexor tendons; thin arrow, flexor retinaculum