FIGURE 2.

(A) Composite image of 4 separate median nerves from the wrists of 4 different participants in the study, cropped and aligned to display the most common variations of bifid median nerves and persistent median arteries. (B) Negative image of these structures, labeled to show the different types of splitting seen with bifid median nerves. In the upper left image, the 2 branches of the nerve (N) are divided by a thick fibrous tissue barrier; in the upper right image, this barrier is much narrower; in some cases the barrier is a very thin partitioning membrane. In the lower left image, the barrier contains a persistent median artery (A). In the lower right image, the artery flanks the nerve, which is not bifid, but the artery (A) is accompanied by 2 smaller veins (V). Although a flanking artery is a common finding with persistent median arteries, it is rare to see persistent median veins.