Nociceptors in the skin and tissues sense stimuli like temperature, pressure, and pH changes, sending signals via nerve fibers.

“And what's going on there in your body is not pain. What's going on is that there are sensors in our skin or soft tissue or deep tissues called nociceptors. And these nociceptors are sensing elements. And they sense different types of stimuli. They can sense temperature, heat, cold. They sense pressure. They can sense pH changes due to, for instance, inflammation that may occur from something going on in your neck or your shoulder.”