Each film or "sequence" in the Human Centipede franchise acts as both a standalone project and as a segment in a larger 4.5-hour film, with the trilogy serving as a 'Movie Centipede'. When Tom Six began creating the Human Centipede sequels, he envisioned a trilogy that works as a "movie centipede".
By attaching the three victims from mouth to anus for sharing a single digestive system, where the consumption of food in the first body reaches to the subsequent bodies as excrement or waste, the surgeon creates a human centipede or what he calls a Siamese triplet.