Hand

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	Hand The hand is a portion of the arm or anterior limb[?] of a human or other primate, at where the appendage[?] terminates. This part of the limb is especially used in grasping and holding. The left hand is the mirror image of the right hand.

What constitutes a hand?

Although many mammals and other animals have grasping appendages[?] similar in form to a hand, these are scientifically not considered to be so, and have other varying names, including paws[?]. Using the term hand is merely a scientific usage of anthropomorphization, to distinguish the terminations of the front paws from the hind ones. The only true hands appear in the mammalian order of primates. Hands must also feature opposable thumbs, as described later in the text.

Structure of the Hand

The hand consists of a broad palm (metacarpus) with five digits, attached to the forearm by a joint called the wrist (carpus).

Digits

The Four Fingers

The four fingers on the hand are located at the outermost edge of the palm. These four digits can be folded over the palm, this allows for the holding of objects, and furthermore the grasping of small objects.

The Thumb

The thumb (connected to the trapezium) is located on one the sides, parallel to the arm. The thumb can be easily rotated 90º, on a perpendicular level compared to the palm, unlike the fingers which can only be rotated approximately 45º. A reliable way of identifying true hands is from the presence of opposable thumbs. Other than opossums (Daubentoniidae), lemurs (Daubentoniidae) and the now extinct dinosaurs, this is a unique feature. Opposable thumbs are identified by the ability to be brought opposite to the fingers.

Bones

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.

Bones of the wrist

The wrist has eight bones, arranged in two rows of four. These bones fit into a shallow socket formed by the bones of the forearm.

Bones of the palm

The palm has 5 bones, one to each of the 5 digits.

Digital bones

Also called phalanges, hands contain 14 of them; 2 in the thumb, and 3 in each of the four fingers.

Muscles and Tendons

The movements of the human hand are accomplished by two sets of each of these tissues.

The Flexors

Located on the underside of the forearm, attached by tendons to the phalanges of the fingers, these allow for the actual bending of the fingers and thumb. The human thumb has to such muscles, moving the thumb in opposition, making grasping possible.

The Extensors

Located on the back of the forearm and a connected similarly to the flexors. Unlike flexors, they are used to straighten out the digits. The thumb has two extensors in the forearm; the tendons of these form the anatomical snuff box.

Articulation

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.

Common uses in English language

I know it like the back of my hand - English phrase used to say that the subject knows the matter perfectly, as if it was part of their body, or that they were born with the knowledge. Related: Second hand.

Second hand - Similar to "I know it like the back of my hand," in that it is definitely known by the subject. Similar to something being described as second nature. Not to be confused with second-hand goods[?], which have already been used before, and are being resold.

A man may also describe somebody as his right hand man, which means that he relies heavily on this person.

A hand is also:

A measurement of length, primarily used for the height of horses, see hand (unit of length).
Something that is like a human hand, such as the rotating pointer on the face of a clock with analog display[?] or on a gauge or dial (hand (mechanisms)[?]).
A hand (language)[?] used in print materials, which is used to call attention to a particular paragraph or point; a lateral direction, (for example, "there is a button malfunctioning on the right hand side of the remote control."), hand (direction)[?].

Oh may.html">may.html">may we soon behold the day when vengeance we shall take!" The next.html">next.html">next day in the morning they fettled them to ride. With every sort of solace e'en to Riodamor. Minaya and the ladies rode forward.html">forward on the track. They have come o'er the river in the place called Vadorrey, The next day in the morning set forth the cavalcade. From Medína to Molína on the next day were they brought. Forth with good.html">good.html">good will he issued to give them welcome high, Thence on unto Valencia they have departed straight. Swiftly he got on horseback, and forth to greet them went. My lord.html">lord.html">lord the Cid came forward his daughters to embrace. "Are ye then come my daughters? 'Gainst ill.html">ill God succor you. May the Creator grant.html">grant it, who dwelleth in the skies, God! on my sons of Carrión grant me avenged to be. And under arms they hastened and came into the town. And he who in good hour was born, he tarried not nor stayed, To King Alfonso of Castile those tidings shall they take. "Where art thou, Muño Gustióz, vassal of fair report To King Alfonso in Castile these tidings do thou take. I am known for his vassal, he for my lord is known-- Shall the good King be troubled in his soul and in his heart. Since my girls they have deserted with great dishonor thus, The great part and the little, my lord's is all the scorn. This and the other insult well may make me ill content. So that I may have justice on the heirs of Carrión, To wait upon his pleasure two horsemen with him rode, They departed from Valencia as fast as they could spur, And the King don Alfonso he found at Sahagún. .

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