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Hand
Human right hand
Latin manus
Vein dorsal venous network of hand
Nerve ulnar nerve, median nerve, radial nerve
MeSH Hand

The hands (med./lat.: manus, pl. manūs) are the two intricate, prehensile, multi-fingered body parts normally located at the end of each arm of a human or other primate. They are the chief organs for physically manipulating the environment, used for both gross motor skills (such as grasping a large object) and fine motor skills (such as picking up a small pebble). The fingertips contain some of the densest areas of nerve endings on the body, are the richest source of tactile feedback, and have the greatest positioning capability of the body; thus the sense of touch is intimately associated with hands. Like other paired organs (eyes, ears, legs), each hand is dominantly controlled by the opposing brain hemisphere, and thus handedness, or preferred hand choice for single-handed activities such as writing with a pen, reflects a significant individual trait.

Some evolutionary anatomists use hand to refer more generally to the appendage of digits on the forelimb, for example, in the context of whether the three digits of the bird hand involved the same homologous loss of two digits as in the dinosaur hand.[1]

Contents

What constitutes a hand?

Many mammals and other animals have grasping appendages similar in form to a hand such as paws, claws, and talons, but these are not scientifically considered to be grasping hands. The scientific use of the term hand in this sense to distinguish the terminations of the front paws from the hind ones is an example of anthropomorphism. The only true grasping hands appear in the mammalian order of primates. Hands must also have opposable thumbs, as described later in the text.

Humans have only two hands (except in cases of polymelia),[2] each of which is normally located at the distal end of each arm. Apes and monkeys are sometimes described as having four hands, because the toes are long and the hallux is opposable and looks more like a thumb, thus enabling the feet to be used as hands. Also, some apes have toes that are longer than human fingers.[3]

The word "hand" is sometimes used by evolutionary anatomists to refer to the appendage of digits on the forelimb such as when researching the homology between the three digits of the bird hand and the dinosaur hand.[1]

Anatomy of the human hand

The human hand consists of a broad palm (metacarpus) with 5 digits, attached to the forearm by a joint called the wrist (carpus).[4][5] The back of the hand is formally called the dorsum of the hand.

Digits

The four fingers on the hand are used for the outermost performance; these four digits can be folded over the palm which allows the grasping of objects. Each finger, starting with the one closest to the thumb, has a colloquial name to distinguish it from the others:

The thumb (connected to the trapezium) is located on one of the sides, parallel to the arm. The thumb can be easily rotated 90°, on a level perpendicular to the palm, unlike the other fingers which can only be rotated approximately 45°Template:Fact. A reliable way of identifying true hands is from the presence of opposable thumbs. Opposable thumbs are identified by the ability to be brought opposite to the fingers, a muscle action known as opposition.

Bones

showing the bones of the human hand.]]

The human hand has 27 bones: the carpus or wrist account for 8; the metacarpus or palm contains 5; the remaining 14 are digital bones; fingers and thumb. The eight bones of the wrist are arranged in two rows of four. These bones fit into a shallow socket formed by the bones of the forearm. The bones of proximal row are (from lateral to medial): scaphoid, lunate, triquetral and pisiform.

The bones of the distal row are (from lateral to medial): trapezium, trapezoid, capitate and hamate. The palm has 5 bones (metacarpals), one to each of the 5 digits. These metacarpals have a head and a shaft.

Human hands contain 14 digital bones, also called phalanges, or phalanx bones: 2 in the thumb (the thumb has no middle phalanx) and 3 in each of the four fingers. These are:

  • the distal phalanx, carrying the nail,
  • the middle phalanx and
  • the proximal phalanx.

Sesamoid bones are small ossified nodes embedded in the tendons to provide extra leverage and reduce pressure on the underlying tissue. Many exist around the palm at the bases of the digits; the exact number varies between different people.

Articulations

Also of note is that the articulation of the human hand is more complex and delicate than that of comparable organs in any other animals. Without this extra articulation, we would not be able to operate a wide variety of tools and devices. The hand can also form a fist, for example in combat, or as a gesture.

The articulations are:

Muscles and tendons

The movements of the human hand are accomplished by two sets of each of these tissues. They can be subdivided into two groups: the extrinsic and intrinsic muscle groups. The extrinsic muscle groups are the long flexors and extensors. They are called extrinsic because the muscle belly is located on the forearm.

The intrinsic muscle groups are the thenar and hypothenar muscles (thenar referring to the thumb, hypothenar to the small finger), the interosseus muscles (between the metacarpal bones, four dorsally and three volarly) and the lumbrical muscles. These muscles arise from the deep flexor (and are special because they have no bony origin) and insert on the dorsal extensor hood mechanism.

The fingers have two long flexors, located on the underside of the forearm. They insert by tendons to the phalanges of the fingers. The deep flexor attaches to the distal phalanx, and the superficial flexor attaches to the middle phalanx. The flexors allow for the actual bending of the fingers. The thumb has one long flexor and a short flexor in the thenar muscle group. The human thumb also has other muscles in the thenar group (opponens- and abductor muscle), moving the thumb in opposition, making grasping possible.

The extensors are located on the back of the forearm and are connected in a more complex way than the flexors to the dorsum of the fingers. The tendons unite with the interosseous and lumbrical muscles to form the extensorhood mechanism. The primary function of the extensors is to straighten out the digits. The thumb has two extensors in the forearm; the tendons of these form the anatomical snuff box. Also, the index finger and the little finger have an extra extensor, used for instance for pointing. The extensors are situated within 6 separate compartments. The 1st compartment contains abductor pollicis longus and extensor pollicis brevis. The 2nd compartment contains extensors carpi radialis longus and brevis. The 3rd compartment contains extensor pollicis longus. The extensor digitorum indicis and extensor digititorum communis are within the 4th compartment. Extensor digiti minimi is in the fifth, and extensor carpi ulnaris is in the 6th.

Variation

File:Female
Female hands

Some people have more than the usual number of fingers or toes, a condition called polydactyly.[6] Others may have more than the typical number of metacarpal bones, a condition often caused by genetic disorders like Catel-Manzke syndrome. The average length of an adult male hand is 189 mm, while the average length of an adult female hand is 172 mm. The average hand breadth for adult males and females is 84 and 74 mm respectively.[7]

Additional images

See also

References

  1. 1.0 1.1 Xing Xu et al.(2009). A Jurassic ceratosaur from China helps clarify avian digital homologies. Nature 459: 940-944 doi:10.1038/nature08124
  2. "Three-armed boy to have surgery". BBC News. 2006-05-31. http://news.bbc.co.uk/1/hi/health/5032906.stm. Retrieved on 2007-12-24. 
  3. http://www.ufovideo.net/
  4. "Nature Bulletin No. 611". Division of Educational Programs, Argonne National Laboratory. 1960-10-01. http://www.newton.dep.anl.gov/natbltn/600-699/nb611.htm. Retrieved on 2007-12-24. 
  5. "hand". Oxford English Dictionary. Oxford University Press. 2nd ed. 1989.
  6. "Polydactyly and Syndactyly". Milton S. Hershey Medical Center, Pennsylvania State University. http://www.hmc.psu.edu/healthinfo/pq/poly.htm. Retrieved on 2007-12-24. 
  7. Agnihotri, A. K.; B. Purwar, N. Jeebun, S. Agnihotri (2006). Determination Of Sex By Hand Dimensions. 1. The Internet Journal of Forensic Science. http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijfs/vol1n2/hand.xml. Retrieved on 2007-12-24. 

External links

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Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

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A human hand.
See also Hand

Contents

English

Most common English words: though « get « eyes « #151: hand » young » place » give
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Etymology

From Old English hand, from Proto-Germanic *handu, from Proto-Indo-European *g̑ʰer- (to grasp).

  • Cognate with Dutch hand, German Hand, Swedish hand.

Pronunciation

Noun

Singular
hand

Plural
hands

hand (plural hands)

  1. That part of the fore limb below the forearm or wrist in a human, and the corresponding part in many other animals; manus; paw. See manus.
  2. That which resembles, or to some extent performs the office of, a human hand; as,
    (a) A limb of certain animals, as the foot of a hawk, or any one of the four extremities of a monkey.
    (b) An index or pointer on a dial; such as the hour or minute hand of a clock
  3. In long measure, two different lengths:
    • (obsolete) Three inches, not to be confused with; and,
    • Four inches, a hand’s breadth, used in measuring the height of horses.
  4. A side; part, camp; direction, either right or left.
    • On this hand and that hand, were hangings. — Exodus 38:15
    • The Protestants were then on the winning handJohn Milton
  5. Power of performance; means of execution; ability; skill; dexterity.
    • He had a great mind to try his hand at a Spectator. — Joseph Addison
  6. (archaic) Actual performance; deed; act; workmanship; agency; hence, manner of performance.
    • To change the hand in carrying on the war. — Edward Hyde Clarendon
    • Gideon said unto God, If thou wilt save Israel by my hand. — Judges 6:36
  7. An agent; a servant, or manual laborer, especially in compounds; a workman, trained or competent for special service or duty; a performer more or less skillful; as,
    an old hand at speaking.
    • A dictionary containing a natural history requires too many hands, as well as too much time, ever to be hoped for. — John Locke
    • I was always reckoned a lively hand at a simile. — William Hazlitt
  8. An instance of helping.
    Bob gave Alice a hand to move the furniture.
  9. Handwriting; style of penmanship; as,
    A good, bad or running hand. Hence, a signature.
    • I say she never did invent this letter; This is a man’s invention and his hand — Shakespeare, As You Like It, IV-iii
    • Some writs require a judge’s hand — Burril
    • 1883, Robert Louis Stevenson, Treasure Island
      I found written on the other side, in a very good, clear hand, this short message...
  10. Personal possession; ownership; hence, control; direction; management; — usually in the plural.
    • Receiving in hand one year’s tribute. — Knolles
    • John Milton, Albinus
      ...found means to keep in his hands the government of Britain.
  11. That which is, or may be, held in a hand at once; as
    (a) (gaming, chiefly card games): The set of cards held by a player.
    (b) (Tobacco Manufacturing): A bundle of tobacco leaves tied together.
  12. Applause.
    Give him a hand.
  13. Agency in transmission from one person to another; as,
    to buy at first hand, that is, from the producer, or when new; at second hand, that is, when no longer in the producer’s hand, or when not new.
  14. (obsolete) Rate; price.
    • Business is bought at a dear hand, where there is small dispatch. — Francis Bacon
  15. Each of the pointers on the face of an analog clock, which are used to indicate the time of day.
  16. (firearms) The small part of a gunstock near the lock, which is grasped by the hand in taking aim.
  17. The collective noun for a bunch of bananas.

Usage notes

Hand is used figuratively for a large variety of acts or things, in the doing, or making, or use of which the hand is in some way employed or concerned; also, as a symbol to denote various qualities or conditions, as,

(a) Activity; operation; work; — in distinction from the head, which implies thought, and the heart, which implies affection.
His hand will be against every man. — Genesis 16:12
(b) Power; might; supremacy; — often in the Scriptures.
With a mighty hand . . . will I rule over you. — Ezekiel 20:33.
(c) Fraternal feeling; as, to give, or take, the hand; to give the right hand
(d) Contract; — commonly of marriage; as, to ask the hand; to pledge the hand.

Quotations

  • 1611King James Version of the Bible, Luke 1:1
    Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us...

Meronyms

Derived terms

Translations

The translations below need to be checked and inserted above into the appropriate translation tables, removing any numbers. Numbers do not necessarily match those in definitions. See instructions at Help:How to check translations.

See also

Appendix: Collective nouns

Verb

Infinitive
to hand

Third person singular
hands

Simple past
handed

Past participle
handed

Present participle
handing

to hand (third-person singular simple present hands, present participle handing, simple past and past participle handed)

  1. (transitive) To give, pass, or transmit with the hand; as
    he handed them the letter.
  2. (transitive) To lead, guide, or assist with the hand; to conduct
    to hand a lady into a carriage.
  3. (transitive) (obsolete) To manage; as, I hand my oar. — Matthew Prior
  4. (transitive) (obsolete) To seize; to lay hands on. — Shakespeare
  5. (transitive) (rare) To pledge by the hand; to handfast.
  6. (transitive) (nautical) To furl; — said of a sail. — Totten
  7. (intransitive) (obsolete) To cooperate. — Massinger

Derived terms

Translations

The translations below need to be checked and inserted above into the appropriate translation tables, removing any numbers. Numbers do not necessarily match those in definitions. See instructions at Help:How to check translations.

References

  • hand in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913

Anagrams

  • Anagrams of adhn
  • NADH

Dutch

Pronunciation

Noun

hand f. (plural handen, diminutive handje, diminutive plural handjes)

  1. (anatomy) hand of a human or other simian

Derived terms


French

Pronunciation

Noun

hand m.

  1. (slang) handball
    On va jouer au hand, tu veux venir?
    We're going to play handball, you want to come?

Synonyms


Old English

Etymology

Proto-Germanic *handuz

Noun

hand f.

  1. hand

Swedish

Pronunciation

Noun

Inflection for hand Singular Plural
common Indefinite Definite Indefinite Definite
Base form hand handen händer händerna
Possessive form hands handens händers händernas
  1. (anatomy) hand; the body part
    Han tjatade jämt om att hon måste tvätta händerna.
    He was always nagging on her to wash her hands.
  2. (card games) hand; the set of cards held by a player
    Hon fick en bra hand, och satsade högt.
    She was dealt a good set of cards, and placed a high bet.

Simple English

[[File:|thumb|200px|A human hand usually has four fingers and a thumb.]]

A hand is the body part at the end of an arm. Most humans have two hands each, usually with four fingers and a thumb. On the inside of the hand is the palm. When the fingers are all bent tightly the hand forms a fist. The joints that are the hardest part of the fist are called knuckles. Many other animals have hands as well, mostly other primates.

The word "hand" is also used in card games. A "hand of cards" is a group of cards that one player can see but others cannot.

Hands are good at grabbing things.

They are also good for hitting things, such as people. Most people use the palm of their hand for this activity.

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