[thedoc (OP)]

Jarryd Dunn  asked the Naked Scientists:
   Dr Smith.
 
I would like to know if there are no pain recepters inside our brain why when you get a head ache does it feel like the pain is actually in side your brain. Could you please explain how it is that it feels like the pain is in your brain.

Many thanks.

Jarryd Dunn

What do you think?

[chris]

Hi Jarryd

This is known as "referred pain"; although the brain itself is full of neurones (about 100 billion, in fact), as you say it contains no pain transducers of its own, so insults to the brain are said to be painless. Indeed, people undergoing brain surgery under local anaesthesia who have consented to brain investigations for research purposes, such as placing electrodes into the brain to record activity or deliver stimulation, report no additional discomfort when their brain is manipulated in this way.

But the tissue layers that invest the brain, called the meninges, are richly endowed with sensory nerve endings that respond to physical and chemical cues. Therefore, irritation to the meninges, by physical (traumatic), chemical (dehydration, bleeding), electrical (as in migraine) or infective (meningitis) processes will stimulate these nerves and be experienced as pain. And because the meninges are in close apposition to the brain surface, the pain is experienced as coming from deep inside the head.

Chris