The answer I heard from a chiropractor trying to solicity my business sounds like a buncha hooey. What’s the real answer?
Think it has to do something with the Referred Pain Phenomenon. Generally the first time a person experiences new pain they get confused as to where it originates.
I would imagine it has to do the position of the heart in the chest cavity. The heart doesn’t sit in the center of the chest. It sort of leans to one side. Also the heart is not symetrical. It has more mass on the left side.
That’s all I can think of for right now.
So far the closest I’ve found to an answer to the specific question is this: The heart “shares” innervation with the chest, arm and jaw. Thus heart pain can be in any of these areas. from here.
Left arm pain is a well-known and well-documented symptom of angina pectoris, which as I understand is a precursor or companion to heart attack. For more info, Google on “angina pectoris” and “left arm”.
I would say that a claim that the association of left arm pain with heart distress could in any way be treated by chiropractic goes beyond hooey to high-grade horsecrap.
I happen to have spent about a year designing equipment for a neurobiologist, many years ago. I picked up a little bit of knowledge while I was there, but one of our resident MDs can probably give more details.
Basically, there’s a lot of what us engineers call “crosstalk” between nerves that are all together within nerve bundles. This means that signals in one nerve get coupled into other nerves. I don’t know exactly how the nerves for the heart are routed, but it’s a safe bet that the nerves for your heart and the nerves for your left arm end up in the same bundle of nerve fibers at some point.
This isn’t unique to your heart either. People with sore throats or bad tonsils often complain about itchy ears, even though there is nothing wrong with their ears. The nerves for their tonsils end up in the same bundle as the nerves for their ears.
That’s intelligently designed, that is.
The internal organs don’t actually have pain nerve endings, so all distress from internal disturbances has to be referred to pain nerves near the surface. Almost always the pain is referred to a point near the affected organ, but not always. The pain from appendicitis, for instance, typically is referred to a point over the right lower abdomen, but on occasion is felt as far away as the right shoulder. Pain from kidney problems often radiates to the groin. And heart attack pain is felt in the left arm, or sometimes the right arm, and sometimes the shoulder. More problematically, heart attack pain can also be referred to the upper abdomen (or lower chest), where it may be mistaken for digestive problems and not be treated right away. This is more common in women, for unknown reasons.
ryobserver-kind of, but not quite. It’s pretty complicated, I’ll try and keep it simple.
The body has two types of nerves that carry sensory information about pain.
Visceral pain is pain is carried by one set of nerves (afferent fibres of the autonomic nervous system). This type of pain is poorly localised, basically because these nerves are designed to tell you that something is seriously wrong, they’re not designed to tell you WHERE. The nerves run into the spinal cord at distinct levels, but there is some variation of these exact levels between individuals.
Somatic pain is carried in a different set of nerves, these are EXACTLY mapped out and there is no variation between people. For example, the skin over EVERYONE’S umbilicus is innervated by nerve fibres coming from the level T10. Somatic pain is thus very well localised-not only do you know you have a problem, you know exactly WHERE it is.
Basically the heart is a visceral organ, so it has the poorly localising type of pain. The heart (innervated approx T1-5) overlaps it’s visceral innervation with the upper limb (approx T2-6) and head and neck (approx T1-3). So pain goes to these places too.
Appendicitis is an example of how the two nerve systems work together.
Early appendicitis is visceral pain from the stretching of the visceral peritoneum overlying the appendix. The pain will be carried in the visceral fibres to T10-11. This causes a periumbilical pain, as the umbilicus is innervated by T10.
If the appendix becomes more inflamed and the peritoneum on the body wall becomes inflamed, the pain will become localised to the Right Iliac Fossa (about 2/3 of the way along a line drawn between your umbilicus and right hip). This is because this outer layer of peritoneum is innervated by somatic nerves, allowing localisation of the pain to the skin overlying the irritated peritoneum.
Now, if the appendix ruptures, pus and blood will track up towards the chest (the person will almost certainly be lying flat from the pain). This gunk will irritate the diaphragm, again causing visceral pain. The innervation of the diaphragm is via the phrenic nerve, which is at the level C3-5, but mostly by nerve fibres from C4.
Now, if you’ve been paying attention I know it won’t come as a shock to learn that the shoulder tip, where pain from the diaphragm is referred, is innervated somatically by fibres from C4.
In short, two pain systems, one good at localising, one not so good. When the second system is the one involved, you can be a bit mixed up about where you feel pain, but there are logical ways to work out why you feel the pains in the odd places you do.