Get a grip! I can handle this. That child is a handful. Did you grasp my meaning? Let’s keep our fingers crossed that everything goes well. This is a hands-on job. This comes handy. I am groping in the dark here.
Language tells us how important the hand is for us humans in many ways. We craft, build, dig, pat, tap, pluck, clap, wave, vow, sign, clasp, clean, eat, feel with our hands. Combining together bio-mechanics and morphological analysis with archaeological and paleontological research – especially of fossils – gives evidence that already in the far-off dawn of human evolution, our distant cousins, Pre-Homo hominins, were tool-users (Kivell 2015)
After joining Nokia Tech, one of the first things I noticed was the white boards and marker pens. As a welcome present I was given a The Dream Catcher –notebook. Rare are the meetings where somebody doesn’t jump up and go to the white board and either draw or write something. Sketching is the thing at Nokia for stretching the mind and why not also the legs and back. Moving around in front of the white board helps many of us to think. When words fail, I and many others draw.
A baby is really fascinated with his/her own hands. Babies spend hours just looking at their hands. Very soon a baby learns how to grasp and to point. Humans are also called pointers. It is claimed that only humans point at things to direct the attention of another person to something. I just heard from a neurologist colleague that the ability of a brain stroke patient to lift the index finger in order to point is one of the best predictors of speed and extent of recovery.
We also like to touch and feel objects. A pat on the shoulder can say more than words. We also have universal hand signs like thumbs up or down, victory with index and middle finger. Showing the middle finger can stir up volatile emotions. Forming a heart with both hands’ thumbs and index fingers is also well understood around the world. The social media is full of hand-related “stickers”.
Tapping one’s fingers can signal boredom, nervousness, eagerness to be on the go. Or one is immersed deep in thought and doesn’t even notice that the finger tips are skipping. When music plays in one’s head some of us just have to let it flow through the fingers – tap tap musicality. Other people can often interpret from the nuances of finger tapping the mood of the tapper.
Many enjoy using their hands. Finger painting, drawing in the sand, making snow balls, waves in the water. I once met a young man at the cashier in a supermarket who did cool finger-tricks with credit cards. I watched with awe how the plastic card moved between his fingers. With a flick of his fingers the card did a somersault and then landed on the palm of same hand. Then he switched hands! I asked him, if he was training for some competition. “No”, he answered, “This is just my way to use the pauses in this work to develop my hand skills”.
During the last year I have spotted people knitting and crocheting in trams, trains, buses, at lectures and even meetings. Swiping and tapping a mobile device is just too boring for our hands and I claim – for our minds and creativity. Research shows that use of hands is important for abstract thinking, problem solving, planning, making sense out of things, cooperation. Thus in terms of human evolution, we are still very much tool users, crafters. We have handling minds that need hands to grasp both literally and metaphorically. Our hand is a tool always with us.
The versatile interplay of arm, as well as the small hand muscles give the human hand its multifaceted and beautifully nuanced functionality. Several different sensory nerves (ranging from fast mini neural routes to multi-lane neural highways) start from the finger tips and run all the way to the sensory cortex of the brain. Their counterpart, motor nerves, start from the motor cortex of the brain and run all the way to the finger tips. These nerves drive hand motor function. The fine tuning and coordination of movement are directed and lead by several other brain area networks and neural circuits located in the frontal lobes, the brain stem (situated deep in the mid-brain), as well as the cerebellum (“little brain”).
Hands on health – shaking hands
A doctor can figure out several things from hands. In this blog I will focus on a few selected examples of medical detective work. First: the hand shake. Is the skin of a person’s palm rough, thick and calloused or smooth? This might give some hints on a person’s profession or hobbies. Is the skin sweaty or dry? If sweaty, the patient might be anxious or have elevated thyroid hormone in the blood. If dry, there might be a lack of thyroxine or the patient might be a too eager washer of hands and have some neurosis related to dirt and being clean. Or the person has sensitive, easily irritable, atopic skin that reacts to dry air, different types of allergens in food or the environment.
A knowledgeable doctor asks after shaking hands with the person seeking consultation: Do you feel like you have an invisible pair of gloves on your hands?” If the answer is yes, sensation of the hands is decreased and the diagnosis of polyneuropathy can be made at the spot. The underlying cause needs further investigation: Is it perhaps diabetes, vitamin B deficiency, excessive use of alcohol, what about drugs?
Grip strength and the way a person grasps your hand give information on muscle strength and hand-arm co-ordination. We doctors want to do right and left-hand handshakes at the same time in order to examine symmetry of function. If weakness is found on one side, a doctor’s mind kicks into further detective mode: Is weakness perhaps due to a damage to the peripheral median nerve in the carpal tunnel located on the palm side of the wrist? This tunnel is surrounded by several arm-muscle tendons. Over-strained stiff muscles cause inflammation and swelling in the tendons – tendinitis. This results in narrowing of the carpal tunnel and the median nerve is in a pinch.
If tapping the palm side of the wrist causes pins and needles –type of pain in the area and/or tingling of 2-4 fingers, the doctor asks: “Do you spend your day using a (computer) mouse? Do you ride a bike to work with a tight grip on the bike handlebars?” So, my readers if you experience these symptoms, you might have a mouse or biker’s hand. And let’s all pay attention to use of our hands. Monotonous hand gripping is often unconscious.
Tremor of the shaking hand(s) can be caused by nervousness, excessive use of alcohol or drugs, too much thyroid hormone in the body, lack of food and sleep – or a problem in the cerebellum (“small brain”). Or the clinical finding can be due to harmless essential tremor that often runs in the patient’s family. Medical detective work continues with further questions to the patient like: “Do you have family members who with age developed trembling hands or a ‘no no’ type of movement of the head?”
The involuntary shaking of the resting hand with thumb tremor brings into mind Parkinson’s disease. Now medical detective work continues with asking the patient: “Could you, please, write your name on this paper”. A typical sign of Parkinsonism is micrographia in which the handwriting is abnormally small. As some people have naturally small penmanship, it is important to compare the writing to something the patient has written earlier. In Parkinson’s disease handwriting becomes progressively and often imperceptibly smaller
After handshakes a doctor asks the patient to do some finger tapping, pointing, clapping, flexing, copying signs with fingers. These hand tasks give a lot of information on the relationships between human cognition, the social brain and the handling mind and health. More complex motor functions of the hands can be quite demanding cognitively.
Feeling the pulse with a finger while examining the patient’s wrist for carpal tunnel syndrome tells the doctor some more: If the pulse is high or the beat erratic and bumpy, thyroid hormone might be the culprit. A fast pulse can also be caused by white coat fright. Just being with a doctor makes some people nervous with shaky hands.
By the way: Why are some people right-handed and some left? Does hand dominance mean that the brains are differently wired? Well, that’s a topic for another Health Bytes blog. Stay tuned. Its sure to come as, being myself a lefty, this is one of my favorite topics.
Kivell TL. Evidence in hand: recent discoveries and the early evolution of human manual manipulation. Philos Trans R Soc Lond B Biol Sci. 2015 Nov 19;370(1682). pii: 20150105. doi: 10.1098/rstb.2015.0105.