Compartment Syndrome

The compartment in this case is our apartment, where we are trapped by Hurricane Irene.

Think about the action of grabbing a piece of food and putting it in your mouth.  This is actually a pretty complicated motion, and two months ago Elliot could perform none of the necessary components (which is how he ended up chopsticking his food.  For an in-depth explanation of chop-sticking, go here.)

In general, he is no longer chopsticking (except to explore intriguing places, like the inside of my nostrils, and the Mummy Ring page of Pat the Bunny).  He can grab a piece of food using what pediatricians call the Pincer Grasp.  But when he does this, something often goes wrong during the food's journey to his mouth.  He can't keep the morsel in that delicate spot between finger and thumb, and it ends up deep in his fist.

For a while this mystified me.  He had pincer-grab perfected, so why the problem?  Then I realized that pincer-grasping a piece of food is just the first step.  Moving it from table to mouth involves more than simply bending the elbow.  To eat a french fry, the hand starts facing down, grabbing the fry, but ends facing up, delivering it to the mouth.  It's the rotation that's the problem.

We don't think of it as challenging to keep one set of muscles still--- in this case, the ones that hold the food--- while flexing another set --- the ones that rotate the wrist toward the mouth.  But of course it's quite challenging if you've never done it before.

The muscles that keep the finger and thumb pinched together, and the muscles that rotate the wrist, are both located in the anterior compartment of the forearm.  (Don't worry, I had to look it up to remind myself.)

So the muscles you're contracting and the ones you are relaxing are literally on top of each other.

It would make sense that it takes an infant a while to learn how to do this.  So I'm trying to go easy on him when he rotates his wrist, all the muscles in his hand go wonky, and his neat pincer-grab turns into a hard-to-eat fistful of Cheerio.

P.S. Yes I will continue to plunder my medical knowledge to justify Elliot's stage of motor development.

P.P.S. Please order me up another hurricane if you are interested in more nerdy posts like this one.