Finally! I’ve been able to put my anatomy lectures to good practical use in figuring out how to map pain. The context was my giving blood today and getting the back of the vein savaged by an incompetent RN. When everything goes well during a donation, I merely feel tired, but when things go poorly, I always wind up with nausea and pain shooting up the bicep into the neck. It turns out that the path of the pain through the bicep and neck run right along the C5 dermatome (ie, the area innervated by the 5th cervical or neck nerve). What has that to do with nausea, you ask? Why, I asked the same, and remembered that adult nervous networks are the same as embryonic ones despite the migration of viscera. This means that the diaphragm is innervated by C3-C5. Moreover, the brain isn’t terribly adept at distinguishing visceral sensory input from dermatome input, so it’s little surprise that damage to one can result in pain from the other. I double checked my anatomy notes and a text or two, and this appears to be the case. Now we know, and knowing is half the battle!

Now the only question is whether I’ll be well enough to run that 5k on Saturday.