Have you ever really sat down and thought about your thumbs? Have you thought about their use? Why we have them at all? What would happen if we didn’t have thumbs that moved the way they do?
Most people definitely do not think about this on a daily basis. As a pediatric Occupational Therapist I am constantly looking at the way infants, toddler, kids, even adults use their hands. How are they holding their pen/pencil? Are they opposing their thumbs or just abducting/adducting them? Do they have adequate web space throughout their thenar eminence? So many fancy words, I know.
As my daughter began to develop her fine motor skills I became more interested in the way her little thumbs were moving. Was she picking things up with just her palm and fingers or was she beginning to use her thumbs? And how were her thumbs moving in general? When you look at all of the ‘childhood milestone’ charts, one of the fine motor skills that should develop between 8-12 months is the pincer grasp. What exactly is this and why is it important?
The true pincer grasp occurs when the thumb and index finger coordinate to hold and manipulate an item. As the pincer grasp develops so does the ability to oppose the thumb. This is the action that makes humans different from primates, right? We have opposable thumbs. So what does this really mean: oppose the thumb? Thumb opposition is the ability to turn and rotate the thumb so that the tip of it can touch each fingertip of the same hand. It allows us to operate tools and grasp objects of various shapes and sizes.
So why is thumb opposition important for my child to develop? What happens if they don’t learn to oppose their thumbs? As parents we typically learn that a pincer grasp is important so that a child can learn to feed themselves. But we parents know that a child does not have to have a precise thumb tip to fingertip grip to feed themselves. Often they can pick up an item of food by ‘raking it in’ (using all fingers and scooping the food into the palm of their hand) and then bring their hand to their mouth and just open their hand in front of their mouth…most of the time some food will make it in. And this type of eating is ok when our children are 6-12 months…but by 1 year the more precise pincer grasp should be emerging.
What many parents are not aware of is the importance that the pincer grasp has on future development. We now know that pincer grasp involves thumb opposition. The development of this skill is important for so many things that we do on an everyday basis. With proper thumb opposition we can easily twist dials, eat finger foods, turn a key in a lock, tie our shoes, turn the pages of a book, open and close a zipper, and use crayons or pencils with precision. It also assists with finger isolation which is another important developmental milestone. Think about it…can you hold up 1 finger distinctively without wrapping your thumb around your other digits? How about 2 or 3? Try it.