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A hand tool is a device for performing work on a material or a physical system using only hands. The hand tools can be manually used employing force, or electrically powered, using electrical current. Virtually every type of tool can be a hand tool and many have also been adapted as power tools, which get their motive power from motors or engines rather than from human mechanical action. Some examples of a hand tools are hammers, spanners and chisels.

Where to buy Hand Tools[link]

Hand Tools are commonly purchased from many distributors/suppliers listed below. Home Depot | Grainger | MSC Direct | MRO Items | Lowes

See also[link]

• Category:Hand tools
• Manual labour
• Antique tool
• Cutting tool
• Garden tool
• Surgical instrument

Hand
Palmar and Dorsal aspects of human right hand
X-ray of human hand
Vein	dorsal venous network of hand
Nerve	ulnar nerve, median nerve, radial nerve
MeSH	Hand

A hand (med./lat.: manus, pl. manūs) is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "hand" and fingerprints remarkably similar to human fingerprints) are often described as having either "hands" or "paws" on their front limbs.

Hands are the main structures 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, feet, legs), each hand is dominantly controlled by the opposing brain hemisphere, so that handedness, or the preferred hand choice for single-handed activities such as writing with a pen, reflects individual brain functioning.

Some evolutionary anatomists use the term hand to refer to the appendage of digits on the forelimb more generally — 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]

The human hand has 27 bones, 14 of which are the phalanges (proximal, medial, and distal) of the fingers. The metacarpal is the bone that connects the fingers and the wrist. Each human hand has 5 metacarpals.^[2]

Definitions[link]

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 two hands 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]

Human anatomy[link]

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 opisthenar.

Digits[link]

The digits of the human hand

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:

• index finger, pointer finger, or forefinger
• middle finger or long finger
• ring finger
• little finger, pinky finger, or small finger

The thumb (connected to the trapezium) is located on one of the sides, parallel to the arm. 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[link]

Bones of the human hand

The skeleton of the human hand consists of 27 bones:^[6] the eight short bones of the wrist or carpus organized into a proximal row (scaphoid, lunate, triquetral and pisiform), which articulates with the skeleton of the forearm, and a distal row (trapezium, trapezoid, capitate and hamate), which articulates with the bases of the metacarpal bones (i.e. the bones of the palm or "hand proper"). Together with the fourteen phalanx bones of the fingers these metacarpal bones form five rays or poly-articulated chains.

Because supination and pronation (rotation about the axis of the forearm) are added to the two axes of movements of the wrist, the ulna and radius are sometimes considered part of the skeleton of the hand.

There are numerous sesamoid bones in the hand, small ossified nodes embedded in tendons; the exact number varies between different people:^[7] whereas a pair of sesamoid bones are found at virtually all thumb metacarpophalangeal joints, sesamoid bones are also common at the interphalangeal joint of the thumb (72.9%) and at the metacarpophalangeal joints of the little finger (82.5%) and the index finger (48%). In rare cases, sesamoid bones have been found in all the metacarpophalangeal joints and all distal interphalangeal joints except that of the long finger.

Articulations[link]

The articulations are:

• interphalangeal articulations of hand (the hinge joints between the finger bones)
• metacarpophalangeal joints (where the fingers meet the palm)
• intercarpal articulations (where the palm meets the wrist)
• wrist (may also be viewed as belonging to the forearm.)

Arches[link]

The fixed and mobile parts of the hand adapt to various everyday tasks by forming bony arches: longitudinal arches (the rays formed by the finger bones and their associated metacarpal bones), transverse arches (formed by the carpal bones and distal ends of the metacarpal bones), and oblique arches (between the thumb and four fingers):

Of the longitudinal arches or rays of the hand, that of the thumb is the most mobile (and the least longitudinal). While the ray formed by the little finger and its associated metacarpal bone still offers some mobility, the remaining rays are firmly rigid. The phalangeal joints of the index finger, however, offer some independence to its finger, due to the arrangement of its flexor and extension tendons.^[8]

The carpal bones form two transversal rows, each forming an arch concave on the palmar side. Because the proximal arch simultaneously has to adapt to the articular surface of the radius and to the distal carpal row, it is by necessity flexible. In contrast, the capitate, the "keystone" of the distal arch, moves together with the metacarpal bones and the distal arch is therefore rigid. The stability of these arches is more dependent of the ligaments and capsules of the wrist than of the interlocking shapes of the carpal bones, and the wrist is therefore more stable in flexion than in extension.^[8] The distal carpal arch affects the function of the CMC joints and the hands, but not the function of the wrist or the proximal carpal arch. The ligaments that maintain the distal carpal arches are the transverse carpal ligament (part of the flexor retinaculum) and the intercarpal ligaments (also oriented transversally). These ligaments also form the carpal tunnel and contribute to the palmar arches. Several muscle tendons attaching to the TCL and the distal carpals also contribute to maintaining the carpal arch. ^[9]

Compared to the carpal arches, the arch formed by the distal ends of the metacarpal bones is flexible due to the mobility of the peripheral metacarpals (thumb and little finger). As these two metacarpal approach each other, the palmar gutter deepens. The central-most metacarpal (index finger) is the most rigid, and it and its two neighbours are untied to the carpus by the interlocking shapes of the metacrapal bones. The thumb metacarpal only articulates with the trapezium and is therefore completely independent, while the fifth metacarpal (little finger) is semi-independent with the fourth metacarpal (ring finger) forms a transitional element to the fifth metacarpal.^[8]

Together with the thumb, the four ulnar fingers form four oblique arches, of which the arch of the index finger functionally is the most important, especially for precision grip, while the arch of the little finger contribute an important locking mechanism for power grip. The thumb is undoubtedly the "master digit" of the hand, giving value to all the other fingers. Together with the index and middle finger, it forms the dynamic tridactyl configuration responsible for most grips not requiring force. The ring and little fingers are more static, a reserve ready to interact with the palm when great force is needed. ^[8]

Muscles[link]

Muscles and other structures of wrist and palm

The muscles acting on the hand 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.

Intrinsic[link]

The intrinsic muscle groups are the thenar (thumb) and hypothenar (little finger) muscles; the interossei muscles (four dorsally and three volarly) originating between the metacarpal bones; and the lumbrical muscles arising from the deep flexor (and are special because they have no bony origin) to insert on the dorsal extensor hood mechanism.^[10]

Extrinsic[link]

Extensor compartments of wrist (back of hand)

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 brevis 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 first four compartments are located in the grooves present on the dorsum of inferior side of radius while the 5th compartment is in between radius and ulna. The 6th compartment is in the groove on the dorsum of inferior side of ulna.

Sexual dimorphism[link]

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.^[11]

Disorders and diseases[link]

• Polydactyly, more than the usual number of fingers or toes. Having more than the typical number of metacarpal bones may be caused by genetic disorders like Catel-Manzke syndrome.
• Syndactyly, fusion of fingers or toes.
• Hand infection
• Hand surgery
• Carpal tunnel syndrome
• Dupuytren's contracture
• Claw hand, paralysis of intrinsic muscles of hand.

Fractures of the hand include:

• Scaphoid fracture
• Rolando fracture - a comminuted intra-articular fracture through the base of the first metacarpal bone
• Bennett's fracture - a fracture of the base of the first metacarpal bone which extends into the carpometacarpal (CMC) joint.^[12]
• Boxer's fracture - a fracture at the neck of a metacarpal

Evolution[link]

"Hands" of a Javanese tree shrew and a human

The prehensile hands and feet of primates evolved from the mobile hands of semi-arboreal tree shrews that lived about a 100 million years ago. This development has been accompanied by important changes in the brain and the relocation of the eyes to the front of the face, together allowing the muscle control and stereoscopic vision necessary for controlled grasping. This grasping, also known as power grip, is supplemented by the precision grip between the thumb and the distal finger pads made possible by the opposable thumbs. Hominidae (great apes including humans) acquired an erect bipedal posture about 3 million years ago, which freed the hands from the task of locomotion and paved the way for the precision and range of motion in human hands.^[13] Functional analyses of the features unique to the hand of modern humans have shown that they are consistent with the stresses and requirements associated with the effective use of paleolithic stone tools. It is possible that the refinement of the bipedal posture in the earliest hominids evolved to facilitate the use of the trunk as leverage in accelerating the hand.^[14]

While the human hand has unique anatomical features, including a longer thumb and fingers that can be controlled individually to a higher degree, the hands of other primates are anatomically similar and the dexterity of the human hand can not be explained solely on anatomical factors. The neural machinery underlying hand movements is a major contributing factor; primates have evolved direct connections between neurons in cortical motor areas and spinal motoneurons, giving the cerebral cortex monosynaptic control over the motoneurons of the hand muscles; placing the hands "closer" to the brain.^[15] The recent evolution of the human hand is thus a direct result of the development of the central nervous system, and the hand, therefore, is a direct tool of our consciousness — the main source of differentiated tactile sensations — and a precise working organ enabling gestures — the expressions of our personalities.^[16]

A gorilla, a large primate with small thumbs, and the hand skeleton of Ardipithecus ramidus, a small Pliocene primate with human-like thumbs

There are nevertheless several primitive features left in the human hand, including pentadactyly (having five fingers), the hairless skin of the palm and fingers, and the os centrale found in human embryos, prosimians, and apes. Furthermore, the precursors of the intrinsic muscles of the hand are present in the earliest fishes, reflecting that the hand evolved from the pectoral fin and thus is much older than the arm in evolutionary terms.^[13]

The proportions of the human hand are plesiomorphic (shared by both ancestors and extant primate species); the elongated thumbs and short hands more closely resemble the hand proportions of Miocene apes than those of extant primates.^[17] Humans did not evolve from knuckle-walking apes, ^[18] and chimpanzees and gorillas independently acquired elongated metacarpals as part of their adaptation to their modes of locomotion.^[19] Several of primitive hand features most likely present in the chimpanzee-human last common ancestor (CHLCA) and absent in modern humans are still present in the hands of Australopithecus, Paranthropus, and Homo floresiensis. This suggests that the derived changes in modern humans and Neanderthals did not evolve until 2.5 to 1.5 million years ago or after the appearance of the earliest Acheulian stone tools and that these changes are associated with tool-related tasks beyond those observed in other hominins.^[20] The thumbs of Ardipithecus ramidus, a CHLCA candidate, are robust like in humans, and thus a primitive trait, while the palms of other extant higher primates are elongated to the extent that some of the thumb's original function has been lost (most notably in highly arboreal primates such as the spider monkey). In humans, the big toe is thus more derived than the thumb.^[19]

Additional images[link]

Static adult human physical characteristics of the hand. Static adult human physical characteristics of the hand.   X-ray of a child's hand   Hands clenched in fists. Hands clenched in fists.   Cutaneous innervation of the upper limbs and hands.   Dissection of hand

See also[link]

• Dermatoglyphics
• Hand strength
• Hand walking
• Handanalysis
• Handstand
• Knuckle-walking

References[link]

External links[link]

Find more about Hand on Wikipedia's sister projects:
	Definitions and translations from Wiktionary
	Images and media from Commons
	Learning resources from Wikiversity
	News stories from Wikinews
	Quotations from Wikiquote
	Source texts from Wikisource
	Textbooks from Wikibooks

• Hand anatomy (eMedicine)
• Watch the National Film Board of Canada documentary Faces of the Hand (Requires Adobe Flash)
• American Society for Surgery of the Hand
• The Common Hand article in the May 2012 National Geographic

v t e Human regional anatomy (TA A01.1) Head Forehead · Ear · Jaw · Face (Cheek, Eye, Nose, Mouth, Chin) · Occiput · Scalp · Temple Neck Throat · Adam's apple Trunk Chest (Breast) · Abdomen (Navel) · Back · Pelvis (Sex organs) Limbs Upper limb Shoulder · Axilla · Arm Elbow · Forearm Wrist · Hand · Finger (Thumb · Index · Middle · Ring · Little) Lower limb/ (see also leg) Hip · Buttocks · Thigh Knee · Calf · Crus Ankle · Heel · Foot · Toe (Hallux · Long  • Third  • Fourth  • Fifth) · Sole General anatomy: systems and organs, regional anatomy, planes and lines, superficial axial anatomy, superficial anatomy of limbs

A modern toolbox.

A tool is any item that can be used to achieve a goal, especially one that is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tools that are used in particular fields or activities may have different designations such as Instrument, Utensil, Implement, Machine, or Apparatus. The set of tools needed to achieve a goal is equipment. The knowledge of constructing, obtaining and using tools is technology.

Tool use by humans dates back millions of years, and other animals are also known to employ simple tools.

History[link]

Prehistoric stone tools over 10,000 years old, found in Les Combarelles cave, France

Carpentry tools recovered from the wreck of a 16th century sailing ship, the Mary Rose.

Stone and metal knives

An upholstery regulator

Anthropologists believe that the use of tools was an important step in the evolution of mankind.^[1] Humans evolved an opposable thumb — useful in holding tools — and increased dramatically in intelligence, which aided in the use of tools.^[2] Because tools are used extensively by both humans and wild chimpanzees, it is widely assumed that the first routine use of tools took place prior to the divergence between the two species.^[3] These early tools, however, were likely made of perishable materials such as sticks, or consisted of unmodified stones that cannot be distinguished from other stones as tools. The beginning of the Stone Age marks the era when hominins first began manufacturing stone tools, and evidence of these tools dates back at least 2.6 million years in Ethiopia.^[4] One of the earliest distinguishable stone tool forms is the hand axe.

Tools are the most important items that the ancient humans used to climb to the top of the food chain; by inventing tools, they were able to accomplish tasks that human bodies could not, such as using a spear or bow and arrow to kill prey, since their teeth were not sharp enough to pierce many animals' skins.

The transition from stone to metal tools roughly coincided with the development of agriculture around the 4th millennium BC. Mechanical devices experienced a major expansion in their use in the Middle Ages with the systematic employment of new energy sources: water (waterwheels) and wind (windmills).

Machine tools occasioned a surge in producing new tools in the industrial revolution. Advocates of nanotechnology expect a similar surge as tools become microscopic in size.^[5][6]

Functions[link]

One can classify tools according to their basic functions:

• Cutting tools, such as the knife, scythe or sickle, are wedge-shaped implements that produce a shearing force along a narrow face. Ideally, the edge of the tool needs to be harder than the material being cut or else the blade will become dulled with repeated use. But even resilient tools will require periodic sharpening, which is the process of removing deformation wear from the edge. Other examples of cutting tools include gouges and drill bits.
• Moving tools move huge and tiny things. For example, concentrating-force tools: the hammer moves a nail, the maul moves a stake, or a whip moves flesh on a horse. These operate by applying physical compression to a surface. In the case of the screwdriver, the force is rotational and called torque. Writing implements deliver a fluid to a surface via compression to activate the ink cartridge. Also grabbing and twisting nuts and bolts with pliers, a glove, a wrench, etc. All these tools move items by some kind of force. Also trucks, rockets and airplanes move larger items and particle accelerators move very small items.
• Tools that enact chemical changes, including temperature and ignition, such as lighters and blowtorches.
• Guiding, measuring and perception tools include the ruler, glasses, set square, sensors, straightedge, theodolite, microscope, monitor, clock, phone, printer
• Shaping tools, such as molds, jigs, trowels.
• Fastening tools, such as welders, rivet guns, nail guns, or glue guns.
• Information and data manipulation tools, such as computers, middleware, IDE, spreadsheets

Some tools may be combinations of other tools. An alarm-clock is for example a combination of a measuring tool (the clock) and a perception tool (the alarm). This enables the alarm-clock to be a tool that falls outside of all the categories mentioned above.

There is some debate on whether to consider protective gear items as tools, because they do not directly help perform work, just protect the worker like ordinary clothing. They do meet the general definition of tools and in many cases are necessary for the completion of the work. Personal protective equipment includes such items as gloves, safety glasses, ear defenders and biohazard suits.

Tool substitution[link]

Often, by design or coincidence, a tool may share key functional attributes with one or more other tools. In this case, some tools can substitute for other tools, either as a makeshift solution or as a matter of practical efficiency. "One tool does it all" is a motto of some importance for workers who cannot practically carry every specialized tool to the location of every work task; such as a carpenter who does not necessarily work in a shop all day and needs to do jobs in a customer's house. Tool substitution may be divided broadly into two classes: substitution "by-design", or "multi-purpose" use, and substitution as makeshift. Substitution "by-design" would be tools that are designed specifically to accomplish multiple tasks using only that one tool. Substitution as makeshift is when human ingenuity comes into play and a tool is used for its unintended purpose such as a mechanic using a long screw driver to separate a cars control arm from a ball joint instead of using a tuning fork. In many cases, the designed secondary functions of tools are not widely known. As an example of the former, many wood-cutting hand saws integrate a carpenter's square by incorporating a specially shaped handle that allows 90° and 45° angles to be marked by aligning the appropriate part of the handle with an edge and scribing along the back edge of the saw. The latter is illustrated by the saying "All tools can be used as hammers." Nearly all tools can be used to function as a hammer, even though very few tools are intentionally designed for it and even fewer work as well as the original.

Tools are also often used to substitute for many mechanical apparatuses, especially in older mechanical devices. In many cases a cheap tool could be used to occupy the place of a missing mechanical part. A window roller in a car could easily be replaced with a pair of vice grips or regular pliers. A transmission shifter or ignition switch would be able to be replaced with a screw-driver. Again, these would be considered tools that are being used for their unintended purposes, substitution as makeshift. Tools such as a Dremel would be considered the substitution "by-design", or "multi-purpose". This class of tools allows the use of one tool that has at least two different capabilities. "Multi-purpose" tools are basically multiple tools in one device/tool. Tools such as this are often power tools that come with many different attachments like a Dremel does, so you could say that a power drill is a "multi-purpose" tool because you can do more than just one thing with a power drill.

Multi-use tools[link]

Bicycle multi-tool

A Multi-tool is a hand tool that incorporates several tools into a single, portable device; the Swiss army knife represents one of the earliest examples. Other tools have a primary purpose but also incorporate other functionality - for example, lineman's pliers incorporate a gripper and cutter, and are often used as a hammer; and some hand saws incorporate a carpenter's square in the right-angle between the blade's dull edge and the saw's handle. This would also be the category in which the "multi-purpose" tools since they are also multiple tools in one (multi-use and multi-purpose can be used interchangeably). These types of tools were specifically made to catch the eye of many different craftsman who traveled to do their work. To these workers these types of tools were revolutionary because they were one tool or one device that could do several different things. With this knew revolution of tools the traveling craftsman would not have to carry so many tools with them to job sites, being that their space would be limited to the vehicle they were driving. The problem of having to deal with so many different tools was solved with the overtaking of multi-use tools.

Tool metaphors[link]

A telephone is a communication tool that interfaces between two people engaged in conversation at one level. And between each user and the communication network at another. It is in the domain of media and communications technology that a counter-intuitive aspect of our relationships with our tools first began to gain popular recognition. Marshall McLuhan famously said "We shape our tools. And then our tools shape us." McLuhan was referring to the fact that our social practices co-evolve with our use of new tools and the refinements we make to existing tools.

In North American colloquialism, the word "tool" may be loosely used to describe an individual of low mental capacity (essentially, an "idiot") or someone who fails to realise that they are being taken advantage of by others.^[7] This metaphor is drawn from the understanding that tools (as understood by most of society) are objects that are used for specific tasks.

Use by animals[link]

Observation has confirmed that multiple species can use tools including monkeys, apes, several birds, and sea otters. Philosophers originally thought that only humans had the ability to make tools, until zoologists observed birds^[8] and monkeys^[9][10][11] making tools. Now the unique relationship of humans with tools is considered to be that we are the only species that uses tools to make other tools.^[12]

See also[link]

• Device paradigm
• List of tool-lending libraries
• Toolbank
• Toolmaker

References[link]

Look up tool in Wiktionary, the free dictionary.

Wikimedia Commons has media related to: Tools