Major superficial veins of the upper limb begin in the hand from a dorsal venous network (Fig. 7.123B), which overlies the metacarpals. The basilic vein originates from the medial side of the network and the cephalic vein originates from the lateral side.
Position of the flexor retinaculum and the recurrent branch of the median nerve
The proximal margin of the flexor retinaculum can be determined using two bony landmarks.