Bodily Oddities

Referred pain

Also called: Reflective pain

Pain from an internal organ often shows up somewhere else, like the left arm during a heart attack or the shoulder from a gallbladder. The nerves from the organ and from that patch of skin share a line into the spinal cord.

Nerves Reflex Reflex

How common

Everyone Universal · ~100% The wiring is the same in all people. Whether you feel it depends on what is wrong inside.

Does this happen to you?

These are answers from visitors, not a study.

How it works

Your skin is mapped in detail in the brain. Touch your fingertip and you know exactly where it is. Your internal organs are not mapped that way. Few nerves come from them, and those nerves enter the spinal cord at the same places as nerves from the skin1.

The leading explanation is called convergence-projection. Pain fibres from an organ and from a patch of skin often end on the same neuron in the spinal cord. That neuron sends one signal up to the brain. The brain has learned, over a lifetime of scratches and bumps, that this neuron means “skin”. So when the organ fires it, the brain places the pain on the skin1. The patch of skin is set by which segment of the spinal cord the organ connects to, and that is the same in almost everyone.

How common it is

The classic patterns are1:

  • Heart attack: left arm, jaw, shoulder, neck, or upper back4.
  • Gallbladder: right shoulder and shoulder blade.
  • Appendicitis: first around the navel, then the lower right belly.
  • Kidney stones: pain travelling from the flank down to the groin.
  • Irritated diaphragm: the tip of the shoulder. This is Kehr’s sign2.
  • Brain freeze: the forehead, from cold on the roof of the mouth3.

The diaphragm and the shoulder are linked because the phrenic nerve, which serves the diaphragm, enters the spinal cord in the neck, next to the nerves for the shoulder2.

Is it a problem?

Referred pain is a normal feature of the nervous system. It matters because it can hide the true source. Doctors are trained to ask about the shoulder when they suspect the gallbladder.

The heart pattern is the one to know. If chest pressure spreads to the arm, jaw, or back, and comes with sweating, shortness of breath, or nausea, call emergency services. Do not wait to see if it passes.

Sources and further material

  1. Encyclopedia Referred pain
  2. Encyclopedia Kehr's sign Shoulder-tip pain from irritation of the diaphragm.
  3. Encyclopedia Cold-stimulus headache Brain freeze is referred pain from the roof of the mouth to the forehead.
  4. Encyclopedia Myocardial infarction Describes the classic spread of heart attack pain to the arm and jaw.
Nerves Involuntary

Brain freeze

A short, sharp headache in the forehead a few seconds after cold food or drink touches the roof of the mouth. It passes in under a minute.

About 30–40% of people
Nerves Involuntary

Precordial catch syndrome

A sudden, sharp, stabbing pain near the heart that lasts seconds to a few minutes and gets worse when you breathe in. It is the most common cause of chest pain in children and teenagers, and it is harmless.

Most chest pain in ages 6–20
Nerves Involuntary

Pins and needles

The prickling, buzzing feeling in a limb after you sit on it or lean on it. It happens when pressure comes off a nerve and the nerve fibres restart at different speeds.

Everyone
Brain Involuntary

Phantom phone vibrations

You feel your phone buzz in your pocket, check it, and nothing happened. Most phone users get this. It is a normal learning effect in the brain, not a fault.

68–89% of phone users