|MadSci Network: Anatomy|
Hi Ben -
The 'pain' in your side probably reflects "referred visceral pain" from your gut. I'll describe what this means below.
You can think of your gut - stomach, small intestine and colon/large intestine - as a long muscular tube with a special lining on the inside. This tube has its own "nervous system" (the enteric nervous system) which includes pain fibers. These fibers primarily respond to two kinds of stimuli:
Why does your side hurt instead of a site more related to the internal location of your stomach?
The pain fibers from your gut enter the spinal cord and travel to the brain. You may know that your "backbone" consists of many bones called vertebrae. Nerves from the spinal cord exit between two vertebrae. Furthermore, these nerves also supply sensation (touch, holt/cold, pain) and innervation (control over muscles) to specific regions of the body. It just so happens that the pain fibers coming from your stomach enter the spinal cord in the same areas as the fibers that detect pain over the left side of your abdomen. For reasons that we don't fully understand, the brain's perception of visceral pain can be referred to the location of the "peripheral" pain fibers that go to areas of skin supplied by nerves coming from the same region of the spinal cord. Weird huh?
You may also find it interesting to know that people suffering a heart attack often feel pain in places as far away as their arm or shoulder. The pain fibers of the heart enter the spinal cord at the same level as fibers supplying sensation to the arms, thus the "referred pain" to these areas.
-L. Bry, MadSci Admin
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