What term describes the formation when two bifurcations on the same ridge join their branches?

The term that describes the formation when two bifurcations on the same ridge join their branches is "spur." A spur occurs when two points where a ridge splits into two separate paths (bifurcations) combine back into a single ridge. This is an important concept in latent print analysis, as understanding ridge formations helps in the identification and comparison of fingerprints.

In contrast, a bifurcation refers to a single ridge that splits into two. A trifurcation can describe a scenario where a ridge divides into three distinct branches, which is a rarer occurrence. The term "fork" also refers to a point where a single line or ridge diverges into two, but it does not specifically imply the rejoining of branches that characterizes a spur. Therefore, the correct term for this specific formation is spur, as it accurately captures the joining of two bifurcations.