A 34-year-old previously healthy male presents to the emergency department with a 6-hour history of severe pain and swelling in his left leg following a minor puncture wound sustained while gardening. On examination, there is only mild erythema and edema over the medial calf, yet the patient reports excruciating pain that he describes as "unbearable" and far worse than the skin findings would suggest. The feature marked **A** in the diagram represents the earliest and most critical clinical clue to necrotizing fasciitis. Which of the following best explains why this disproportionate pain is the cardinal early warning sign of necrotizing fasciitis?