What is the anatomy and physiology of muscle pain?
The relatively few pain receptors that reside in the muscles are not freely accessible to their surroundings. They are protected by a hard capsule inside small anatomical sites called muscle spindles. These are about the size of a grain of rice. These spindles, randomly dispersed throughout all skeletal muscle, but more concentrated at the back of the neck, are filled with liquid and contain even tinier muscles called intrafusal fibers. The muscle spindles contain most of your pain, pressure, and stretch receptors. The surrounding capsule protects those receptors from the constant movement of adjacent muscles. It saves you from feeling pain during normal movement. Those receptors can eventually become irritated. They have recently been shown to become irritated when people are overloaded, intense, focused, overworked, hyper-vigilant, worried, and/or overwhelmed. That begins to explain why you often hurt more when you have more things going on in your life. Itís especially true at work
