The Thumb Wrap Pencil Grasp
Which is stronger, the thumb or forefinger? I am trying to figure out why the thumb wraps over the forefinger so frequently.
When a child wraps his or her thumb over, the child is attempting to increase stability of the pencil by substituting muscles. Instead of using the muscles for opposition, primarily the Opponens Pollicis and he or she is switching to using the Adductor Pollicis for a type of modified key grip on the pencil. The thumb abductor muscle is stronger, but innervated by the ulnar nerve. Feel the strength this muscle in yourself by putting your index finger in at the base of the thumb to resist adduction of the thumb. It's very strong. This muscle innervation by the ulnar nerve is not designed for speed/dexterity, it is slower firing. So as these children are going for pencil stability and they are sacrificing writing speed in the long run. When I ask adults about the wrapped grip, they relate having a lot of fatigue in the forearm muscles when having done a lot of note taking in college. See Mary Benbow's writing to learn more about the anatomy/neurology.
The thumb wrap prevents the skilled use of the thumb. There isn't the movement of the thumb from moving from flexion to extension of the IP to advance the pencil. Children are doing a lot more of using the forearm muscles to move the pencil A lot of children have learned to hyperextend their thumb to do fine motor due to lax ligaments in the thumb. One has to teach them to flex their thumb to properly use the Flexor Pollicis Longus muscle. A verbal cue I use is, "make a mountain." So children benefit from marking the thumb IP with an small "X" to draw attention to the joint.. Another verbal cue I use is, "Don't let your thumb take a vacation." When I work on the flexion of the thumb though focusing on the child getting flexion of the thumb IP, that improves opposition. The Flexor Pollicis Longus works in conjunction with the Opponens Pollicis, since the OP is right at the base of the thumb, it is activated as long as there is an open webspace. A pickle forks (a.k.a. 3 pt grabber from Pocket Full of Therapy) work beautifully for strengthening these muscles. I try to get the child to be able to be strong enough to pick up 20 - 30 manipulatives with the fork. It's a nice activity also, because data collection on progress is easy to keep.
I've found that one has to work on hand strengthening (mainly extrinsics) to maintain an open webspace (using a pencil grip in the mean time) and also working on strengthening the intrinsics of the hand/thumb.
For modifications see the following article on otexchange.com
Adaptations to Increase Grip on Writing Utensils (Handwriting section)
Do you have any experience in correcting that in middle school age children or 2nd-4th grade?
Yes, I do have experience with changing grasps in 2nd to 4th grade. I worked in the school setting for 10 years. I cowrote the article Adaptations to Increase Grip on Writing Utensils ( Handwriting section on otexhange.com) to put forth an different theory for developing pencil grasps that I have successfully used. The greatest percentage of 2nd to 4th grade children were happy to work on it, if I focused on strengthening issues and pincer grasp (from Activities to Develop an Efficient Grasp), while not being too focused on writing. I provide a pencil grip in the mean time. They really do love doing thumb strengthening with a pickle fork and a metal ice grabber. The ice grabber provides a little more resistance than the pickle fork.
When I want to transition more toward writing, after their hand/thumb strength is better, I start working on pencil control (adjusting or decreasing support from pencil grips, as needed) and having the child do fun visual motor worksheets. We focus on doing these visual motor activities, while practicing maintenance the "O" shape of the thumb/index fingers. It helps to also practice finger excursion or the movement of thumb-index finger together, with the ulnar side of the hand stationary on the table. This can be done by painting a small 2" x 2" picture with small watercolor sets, as found in the party favors section. The watercolor pencils from Crayola are fun. First have the child color in a small picture and then paint it with water. Some children benefit from having a little pad or circle (sand paper or other texture) to rest the ulnar side of their hand on. They use the pad while practicing coloring with the radial fingers, while they keep the base of the hand still or on its pad. Finger excursion can also be practiced with tweezers. Just experiment to get the right heights/positoning of your setup.
Note about Ice Grabbers: They used by be carried by PFOT. Currently, the only source I've found for them is the Total Home Store. These ice grabbers provide more resistance, than the onces that used to be carried by PFOT, which is a bit disappointing. The resistance is probably too great for most children. I'd like to find another source for grabber with less resistance.So if you find a better source, could you share the information with me? In general, the children really love using the ice grabbers. They work well for picking up hedge balls from the Oriental Trading Company.
I wrote in a couple of weeks ago about a student I have with a hyperextended thumb IP joint which was causing him pain when writing. I have had the assistance of another therapist in my district and have set this student up with a figure eight splint, as some of you all suggested. This other therapist also thought it would be a good idea to have him do some thumb exercises. I am wondering though if strengthening the thumb will actually help this. I'm sure it couldn't hurt. What are some exercises I could have him do independently (he's in 5th grade)? I thought I would give him some theraputty. Thanks for any ideas!
My favorite tool to start with is a pickle fork, (cheapest through a kitchen supply, if you can find them there, or as the "Three Point Grabber" available through Pocket Full of Therapy or a "Wire Wizard Picker Upper" from Therapy Shoppe). I work to get the child to to the point of having enough strength to pickup 20 pom poms and dropping them in an Altoids container held by their non-dominant hand.
A child with very lax thumb ligaments may need to wear the figure eight splint splint or kinesio tape to support the MP of the thumb, while doing doing the exercises.(see note below). I haven't had too much luck with Benik splints, due to its hampering of movement. These exercises are compromised, if they are done with hyperextended joints. You might also encourage a child to do activities for gross strengthening of the hand, i.e. take him or her out on the playground and spot him on the bars. Is he grasping with the thumb around the bar or avoiding using his thumb by placing it along side the index finger and just hanging by the 2nd to 5th fingers. Also see: Hand Strengthening Ideas
After the child is able to go 20 pickups with the pickle fork, I move them up to doing 20 pickups with a metal ice cube grabber. Once they hit this point, they can independently hold the pencil properly with some verbal cues for reminders of positioning.
Note: In regards to an unstable thumb MP joint, I have heard that the two things that OTs are using, are either a figure-eight splint or kinesio taping of the MP joint. I haven't had a child lately with an unstable MP joint to try them both, to see which works the best. I'd be happy to hear on any one's experience in successfully helping a child with this difficulty.
PS. the five developmental levels of the hand are listed in my article: "Fine Motor for Preschoolers" at: :http://make-the-grade-ot.com/Fine%20Motor.html