Saturday, May 28, 2005

So now we know...

An email friend who is also an MD solves the mystery of the tinny taste I've been getting when scritching my left ear:

There is a very good explanation for the funny taste you get while probing your ear: it goes back to our fishy ancestry when we all had gills.

The three bones in the middle ear cavity were originally part of a bony arch reinforcing one of the gill-slits, just as the mandible and upper jaw formed part of another gill-arch. Associated with each of these arches was a nerve, still in existence but now serving a slightly different purpose. Several of these nerves connected with the tongue, carrying taste-messages.

When the architecture of hearing and chewing was rearranged, as it is in mammals including us, one tiny taste nerve, the Chorda tympani, was left stranded so that it had to pass across the eardrum, pass out through a hole in the temporal bone and into the tongue, where it mediates taste along the edge of the tongue. So when you poke your ear, it irritates the chorda tympani, sending a false signal to your brain.

Don't tell the Creationists about this though.

aj


Shhh. I won't if you don't.

But if you're up for more explanation, why a metallic taste? And why two months after the implant?

Any theories?

Waiting with bated (or, perhaps, baited) breath,

ronnie

4 Comments:

Anonymous Anonymous said...

The metallic taste probably belongs to that group of sensory experiences known as phantom sensations: these sensations have no real-world origin, but occur as a result of nerve impulses being triggered somewhere along the course of the nerve, or within the brain itself.
Metallic tastes are known to occur when gustatory (taste) nerves are damaged or temporarily inactivated, as can happen during injection of local anesthetic in dental anesthesia. Btw, which side is your CI-- is it on the same side as the metallic taste?
aj

9:08 p.m.  
Blogger ronnie said...

Yes - the CI is on the left - the same side where I'm getting the metallic taste. No similar effect on the right side.

Thanks much for the info. Seems to be a delayed reaction to the surgery, then. Or a side-effect of the healing.

Whatever it is, it's an oddity and not a problem - particularly considering that one of the potential side-effects I was told about was a temporary or permanent change in taste on that side. This is more a... personal party-trick :)

ronnie

10:22 p.m.  
Anonymous Anonymous said...

On the subject of senses, if you want to read a sumptuous celebration of these faculties, read Diane Ackerman's 'Natural History of the Senses', also, her book 'Cultivating Delight', on the joys of gardening.
aj

5:00 p.m.  
Anonymous Sister said...

The metallic taste is probably the fact that you are in a sense, tasting your own spit. (Ewwww). The body's natural fluids (as opposed to UN-Natural fluids? O_o I won't go there.) have a high metallic content in them anyway. Just look at your blood. It's common for people when they have bad breath to have a tinny taste because they're experiencing their own saliva taste. Or it could just be that your own tastebuds are predisposed towards metal. Do you find you can taste salt easily, sis?

5:34 p.m.  

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