This was possibly my most important lesson about the individual differences in muscle and connective tissue qualities, a lesson that would be reinforced throughout the years as I taught students with far more flexibility - and some far less - than I inherited. I have had students with "spider" hands and some with "Daddy Long-legs" hands. I have also had students who were challenged to open to a sixth - "ant" hands?
It is important to understand the difference between muscle and connective tissue. Muscle moves bones, and it is designed to be able to shape-shift quickly in order to accommodate a wide variety of movements. According to Anatomica, a beautifully illustrated home anatomy book published by Firefly Books, connective tissue is designed to "bind, support or strengthen organs or other tissues". (p. 21) There are various types of connective tissues, but we will be concerned mainly with dense connective tissue as we look at finger movements.
The two types of connective tissue that we deal with most often when learning about movement are tendons and ligaments. Tendons connect muscles to bones, and ligaments connect bones to bones, generally crossing joints. Possibly the most famous of tendons, if fame be so attributed, would be the Achilles tendon. This tendon attaches the calf muscle to the heel and is critical to uprightness and leg movement. Both literally and metaphorically, it is one of our most vulnerable areas.
Likewise there are tendons that connect muscles of the forearm to the fingers. These tendons are long, dense, and responsible for the movements we call flexion and extension. Flexion is the movement fingers make as they bend toward the palm. Extension is the movement fingers make as they open away from the palm. The flexor tendons and muscles are on the under side of the arm, and they provide the range of bending motion for fingers at the MCP joints. This range of motion creates a variety of options for the natural arch that occurs at the MCP joints. The extensors, on the upper side of the arm, can not move fingers far above what looks to be a level position between the metacarpals (in the palm) and the phalanges (the three bones that most people call the fingers).
When I first learned about these long, strong tendons, I was surprised that my fingers were controlled in large part by the muscles of the forearm. I had thought that finger "strength" came from developing finger muscles. However, the insistent pain I had developed in my forearms fit with my new understanding of the relationship between forearm muscles and finger movement. The more forceful I was with my fingers, the more tense I was in my forearms.
There are genetically controlled individual differences in tendon structure that can affect the range of motion of fifth fingers. As you can see from the illustration below, there is some interconnectedness between the finger tendons, a reminder to reconsider the concept of finger independence exercises. Some hands have a strong connection between four and five that decreases the ability of five to flex on its own. You can explore your own hand for this trait by holding fingers two, three and four together, then attempting to flex finger five toward the palm. In my case, it won't go far at all. Some people have one fifth finger which can flex during this experiment while the other one can not.
|Left hand palm side down, showing extensors|
So, if tendons are not "elastic", how was it that Pressler and my arachnid students could do what they did, which appeared to be stretching? Tune in to Part Four....