|More about Thumb Opposition
and oppose, the tips of all the fingers. Having opposable thumbs is an important environmental
adaptation that has set primates, which includes humans, apart from the rest of the animal
kingdom. It enables us to do things with one or two hands that would be impossible to
accomplish by organisms that don't have thumbs. The thumb is the shortest digit on the hand
yet it is controlled by more muscles than the other digits. It is able to move in more
directions because of the unique joint it has at its base.
Children begin to develop thumb rotation to form a spherical grip between their 1st and 2nd
year of life. The thumb begins to develop a better ability to rotate and oppose the other
fingers. For a variety of reasons, many children lack the thumb stability for sustaining the
thumb in a partially bent position when using writing and drawing tools. They have difficulty
holding implements between the tip of the thumb opposing fingertips. They substitute by
using stronger hand muscles that pull the thumb straight up beside the index finger or wrapped
over other fingers when writing and drawing. This causes hand fatigue and difficulty grading
the amount of pressure for pushing a pencil or crayon. Control is less precise and work may be
would you be able to write with a pencil? Brush your teeth? Open or close the lid on a jar?
How long would it take you to tie your shoelaces if you tried to do it with only your fingers?
Even something as simple as turning a doorknob, tying a knot in a balloon or turning a key.
An important aspect of having a rotating thumb is that it is able to form a "web space"
between it and the index finger when both tips touch and form a circle. Think of the A-ok
sign. It is called a "web space" because of the extra skin at the base of the thumb and index
finger that has the appearance of a web, similar to animals that have webbed toes. An open
web space is important for holding writing and drawing tools correctly. When the space is open
and the writing tool is held with the thumb tip and fingertips, this allow for greater precision
and control. Written work and drawings are more accurate. There is less stress on the joints
of the hand and, thus, less writing fatigue.
Activities to Open the Web Space
Clay, therapy putty, Silly putty, play-doh, Sculpey, bread dough, modeling foam (Crayola Model Magic)
Pocket Full Of Therapy