"When we stood on our back legs that allowed the fore legs to no longer be fore legs and the paw to no longer be a paw. We developed an arm and a hand and that hand manipulates things, it allows us to prepare food, we write, we gesture, we wipe our bottoms; we act in the world on ourselves and on others through the hand. It changed most things that we do in ways that we take for granted and with the development of the hand comes more refined movement than other animals do, movements of finger to finger, caressing of things etc. And when Bell first described the hand as an instrument he immediately said that we needed to evolve with the evolution of the hand an area of the brain that controls the action of the hand. So within the brain there is a large increase in the area called the motor and sensory cortex, which appears to be crucial for coordinated action of the hand, but also the sensation that required to guild action too. So if I put my hand in my pocket to collect coins, I have to manipulate the coins in order to pick them out without seeing them. And requires what is called active touch, an intimate relationship between the sensation that we get and the movement that we make."
The hand at rest, and in movement, is affected very differently in individual peripheral nerve entrapments, (median, ulnar or radial) and in more generalized diseases of the nerves. In some conditions e.g. rheumatoid, scleroderma, osteoarthritis, the hand’s shape changes and can even appear distorted. Patients can be as distressed by the appearance as much as by the reduced function of their hands. For our hands are more than mere instruments; they are their means of acting in the world and of relating to others. A stroke can render the hand paralyzed, and insentient. The sense of loss this engenders can be seen in the way patients’ cradle and hold their hands, visible but inanimate. In spinal cord injury the hands can be weakened and scarcely useful and yet appear graceful and lithe. For hands are not simply tools to use, they are aesthetically rich and convey crucial communications. With loss of hand function, gesture and communication and with them interpersonal skills can change. Some with hand tremors will conceal their affliction, almost out of shame that such a vital part of themselves is so affected.