Re: Why do heart attack symptoms usually involve the left arm and shoulder ?

Often a painful area of the body is not site of the reason for that pain. This is called referred pain. Referred pain is very common. It's defined as pain perceived in another area, often far from the origin. Pain down the inside of the left arm and forearm when a person suffers a heart attack is a common example. Other examples of referred pain include:

Although related to messages sent by the nervous system telling the brain what area hurts, the reasons for referred pain are not completely known. What's important is the fact that when there's pain in these (and other) areas, it may indicate a hidden problem in some other part of the body.