Trivial yet fascinating true facts about the human hand.
Hands are Everywhere
  • A recent search of the the National Library of Medicine for word "hand" retrieved 145978 scientific articles. Click here to see today's tally. 
  • A recent search of the internet for the word "hand" through retrieved 20390195 web pages. Click here to see today's tally. 
  • One third of all acute injuries seen in emergency rooms involve the upper extremities.
  • Two thirds of upper extremity injuries occur to individuals in their working years.
  • The most common disabling work injuries in the United States involve the upper extremities, accounting for over one fourth of all disabling work injuries. One out of six disabling work injuries involve the fingers, most often due to the finger striking or being struck against a hard surface. 
  • One fourth of athletic injuries involve the hand and wrist.
  • Children under the age of six are at the greatest risk for crushing or burning injuries of the hand.
Remote control fingers
We work our fingers by remote control. Of course, in one sense, we work all of our moving body parts by remote control - the control center is our brain. However, the fingers are special, because there are no muscles inside the fingers. The muscles which bend the finger joints are located in the palm and up in the mid forearm, and are connected to the finger bones by tendons, which pull on and move the fingers like the strings of a marionette. 
  • When the hand is kept wet, the skin of the palm wrinkles. Why? The exact mechanism is not known, but it is clearly controlled by nerves. When the nerve which supplies feeling to an area of skin on the palm is cut, that area of skin not only becomes numb, loses its ability to wrinkle when wet. It also loses the the ability to sweat.
    Nerves wrinkle test
  • The wrinkles on the back of the finger knuckles are actually dimples, and mark areas where the skin is attached to the tendon beneath the skin.
  • Finger joints only have wrinkles and creases if the joint moves. If a finger joint stops moving, the creases eventually flatten out.
  • One out of six of congenital anomalies recorded on birth statistics involve the upper extremities.
  • White children are four times more likely than black children to be born with webbed fingers.
  • Black children are ten times more likely than white children to be born with extra fingers.
    syndactyly polydactyly
  • Each hand contains (plus or minus... everyone is different, and everyone counts these things differently...)
    • 29 major and minor bones (many people have a few more).
    • 29 major joints.
    • At least 123 named ligaments.
    • 34 muscles which move the fingers and thumb:
      • 17 in the palm of the hand, and
      • 18 in the forearm.
    • 48 named nerves:
      • 3 major nerves.
      • 24 named sensory branches.
      • 21 named muscular branches.
    • 30 named arteries and nearly as many smaller named branches.
Finger strength
    The muscles which power the fingers are strong - strong enough for some people to climb vertical surfaces supporting their entire weight at times by a few fingertips. The muscles which accomplish this feat are stronger than you might imagine, for the biomechanics of the hand require that the force generated by the muscles which bend the fingertips must be at least four times the pressure which is produced at the fingertips
Thumb movement
  • The thumb is controlled by
  • And moves in such a complex fashion that there are 6 separate descriptive terms just for particular directions of movement of one thumb joint - the basal joint, at the base of the thumb.
    Almost 90 per cent of women and 80 per cent of men in the age group 75-79 years have x-ray evidence of osteoarthritis in their hands <·>.
    Contrary to popular opinion, humans - homo sapiens -  are not the only primates posessing opposable thumbs. Chimanzees and monkees can oppose the thumb to the index digit. What makes the human hand unique in the animal kingdom is the ability of the small and ring fingers to rotate across the palm to meet the thumb, owing to a unique flexibility of the carpometacarpal joints of these fingers, down in the middle of the palm. This is referred to as "ulnar opposition" and adds unparalleled grip, grasp, and torque capability to the human hand. This feature developed  after the time of Lucy, a direct human ancestor, who lived about 3.2 million years ago. 
Fingernail feeling
    Do fingernails have feeling? No, but the fingernail extends deep beneath and behind the skin of the cuticle, and nerves on the back of the finger around the cuticle sense forces transmitted from the tip of the fingernail. The brain integrates the sensations from the nerves of both the fingertip pad and cuticle to give a complex enhanced perception of pressure and shear at the fingertips. Loss of a fingernail changes the feeling on the palm side of the fingertip.
Hand words
Hand and Brain
    About a quarter of the motor cortex in the human brain (the part of the brain which controls all movement in the body) is devoted to the muscles of the hands. This is usually illustrated with a drawing of a human figure draped over the side of the brain, body parts sized proportional to the amount of brain devoted to their movement, referred to as a homunculus - as illustrated in this drawing from Dr. Wilder Penfield's monograph "The Cerebral Cortex of Man.":
Hair and nails
    Structurally, fingernails are modified hairs.
Carpal tunnel syndrome
    In one study, carpal tunnel syndrome was found in 9 percent of women between the ages of 25 and 74.
The skin of the palm
The skin on the palm side of the hand and fingers is unique for these reasons and more: 
  • No hair (the medical term is glabrous).
  • Fingerprints.
  • Usually neither color nor the ability to tan.
  • Tough and durable, yet sensitive. 
  • Anchored down to the bones beneath through an intermediate layer of fascia. This arrangement keeps the skin of the palm from sliding around like a rubber glove when we use our hands to grip and twist. In some people, this layer of fascia shrinks and thickens, leading to Dupuytren's disease.
Overlapping fingers
When one curls the fingers into a fist, the fingertips naturally group together side by side. If the fingertips all bend together, they continue into the palm side by side. However, the natural tendency is for each fingertip to aim for the same point at the base of the thumb, which is obvious when touching each finger down to the base of the palm. For this reason, if a hand problem (stiffness, swelling, etc.) prevents a finger from meeting the side of the adjacent fingertip midway into making a fist, that finger will tend to cross over and overlap the adjacent finger when making a fist.
convergencecrossed fingers
Urban legends
  • "If you can move your finger, it isn't broken" False.
  • "Cold hands, warm heart" Well, it really depends on why ones hands are cold...
  • "Computer use causes carpal tunnel syndrome" Probably false.
  • "Eating gelatin makes your fingernails stronger" False - no evidence to support this.
  • "Cracking your knuckles gives you arthritis" False - no evidence to support this.
Curved fingers
  • Fingers are never perfectly straight. Usually, the index, ring and small finger each curve sideways slightly toward the middle finger, and the middle finger may curve toward either side.
  • The finger bones are straight on the back side, but curved on the palm side. When we bend our fingers into a fist, the finger bones produce a shape similar to a circle in a square,  round on the inside, square on the outside.
  • When we make a fist, the fingertips curve through a spiral, not a circle. This is because the lengths of the finger bones are related in a way seen often in naturally occuring spirals. These spirals in turn relate to a mathematical series of numbers discovered by Fibonacci in 1202. In this series, each number is the sum of the previous two numbers: 0, 1, 1, 2, 3, 5, 8, 13, 21, ...and so on. The lengths of the finger bones approximate the ratio of the Fibonacci numbers 2, 3, 5, and 8. 
Definitions of hand:
  • verb:   place into the hands or custody of
  • noun:   ability
  • noun:   a card player in a game of bridge
  • noun:   a hired laborer on a farm or ranch
  • noun:   a member of the crew of a ship
  • noun:   a position given by its location to the side of an object
  • noun:   a rotating pointer on the face of a timepiece
  • noun:   a round of applause to signify approval
  • noun:   a unit of length equal to 4 inches; used in measuring horses
  • noun:   one of two sides of an issue
  • noun:   physical assistance
  • noun:   something written by hand
  • noun:   terminal part of the forelimb in certain vertebrates (e.g. apes or kangaroos): "the kangaroo's forearms seem undeveloped but the powerful five-fingered hands are skilled at feinting and clouting"- Springfield (Mass.) Union 
  • noun:   the cards held in a card game by a given player at any given time
  • noun:   the (prehensile) extremity of the superior limb
The Practice
Hand Surgery as a recognized surgical specialty did not exist until World War II. At that time, US Army Surgeon General Norman Kirk arranged for military hand injuries to be treated at regional specialty centers. Dr. Sterling Bunnell, a civilian general surgeon who had written a book about the care of the hand, was assigned the task of supervising and training a nucleus of hand surgery specialists. This group became the first generation of surgeons in the modern specialty of hand surgery. 
Thumbs away!
During the Gallic wars, Julius Caesar ordered the thumbs of captured warriers amputated so that when they returned to their country, they would serve as examples and be unable to bear arms again. This practice was later used in a number of wars and in the slave trade.

In the absence of any other proof, the thumb alone would convince me of God's existence.
Sir Isaac Newton

We can land men on the moon, but, for all our mechanical and electronic wizardry, we cannot reproduce an artificial fore-finger that can feel as well as beckon.
John Napier

The hand is the cutting edge of the mind.
Jacob Bronowski
You can't shake hands with a clenched fist.

Indira Gandhi 
The fragrance always remains in the hand that gives the rose.

Heda Bejar
Hold a true friend with both hands.

Nigerian Proverb
Nor do not saw the air too much with your hand, thus, but use all gently.

William Shakespeare, 'The Tragedy of Hamlet, Prince of Denmark,'Act III, scene ii
The preservation of the sacred fire of liberty and the destiny of the republican model of government are justly considered... deeply,...finally, staked on the experiment entrusted to the hands of the American people.

George Washington, First Inaugural Address, Apr. 30, 1789
May the road rise to meet you. May the wind always be at your back. May the sun shine warm upon your face, the rains fall soft upon your fields and, until we meet again, may God hold you in the palm of his hand.

Irish Blessing
Do not withhold good from those to whom it is due, when it is in the power of your hand to do so.

Proverbs 3:27
The impersonal hand of government can never replace the helping hand of a neighbor.

Hubert H. Humphrey
The upper limb is the lightning rod to the soul.

Robert Markison

The art of life is to show your hand.
E. V. Lucas
The best helping hand that you will ever receive is the one at the end of your own arm.

Fred Dehner
Children are the hands by which we take hold of heaven.

Henry Ward Beecher

A child's hand in yours -- what tenderness and power it arouses. You are instantly the very touchstone of wisdom and strength.
Marjorie Holmes
The ultimate test of a relationship is to disagree but hold hands.

Alexander Penney
Criminals do not die by the hands of the law. They die by the hands of other men.

George Bernard Shaw
Ignorant men don't know what good they hold in their hands until they've flung it away.

PALMISTRY, n. The 947th method (according to Mimbleshaw's classification) of obtaining money by false pretences. It consists in "reading character" in the wrinkles made by closing the hand. The pretence is not altogether false; character can really be read very accurately in this way, for the wrinkles in every hand submitted plainly spell the word "dupe." The imposture consists in not reading it aloud.

Ambrose Bierce
Infinite striving to be the best is man's duty, it is it's own reward. Everything else is in God's hands.

Mahatma Gandhi
To make a man happy, fill his hands with work.

Frederick E. Crane
How did I develop an interest in hand surgery? Click here for the story.