Pain Transmission
To understand why we feel pain and how to treat it, it is helpful to know how pain messages travel between the brain and the part of the body that hurts.
Pain signals move across a complex network of nerve fibres that reaches into all areas of the body. This network has three main components:
The peripheral nerves extend from the spinal cord to the skin, muscles, and internal organs. These nerve fibres vary in size and in the rate at which they carry messages.- The peripheral nerves end at the spinal cord, which releases chemicals called neurotransmitters that help pain signals jump from one nerve fibre to the next, allowing the pain message to reach the brain.
- The brain receives the pain signals and sends them to the specialized areas that control physical sensations, emotional feelings, and rational thought. This determines how you react to the pain. For example, you may scream or become anxious about how the injury may affect your life. Sometimes during a crisis, the brain will release natural pain-killing chemicals that keep you from feeling the pain during the emergency so that you can do what needs to be done.
While the nerves are transmitting pain signals from the injury to the spinal cord to the brain and back, there are reactions taking place at the injury site that can cause inflammation, which results in swelling, redness, warmth, and increased pain.
This can lead to a vicious cycle—particularly in cases of chronic pain—in which the pain triggers muscle tension or spasms, which causes more pain, leading to increased tension, and so on until the cycle is broken.
