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59-423: The English word finger has two senses , even in the context of appendages of a single typical human hand: 1) Any of the five terminal members of the hand. 2) Any of the four terminal members of the hand, other than the thumb. Linguistically, it appears that the original sense was the first of these two: * penkwe-ros (also rendered as * penqrós ) was, in the inferred Proto-Indo-European language ,

118-417: A guy , is a tensioned cable designed to add stability to a freestanding structure. They are used commonly for ship masts , radio masts , wind turbines , utility poles , and tents . A thin vertical mast supported by guy wires is called a guyed mast . Structures that support antennas are frequently of a lattice construction and are called " towers ". One end of the guy is attached to the structure, and

177-402: A dead man. This type consists of a rod with wide screw blades on the end and an eyelet on the other for the guy wire. It is screwed deep into the ground, at the same angle as the guy, by a truck-mounted drill machine. These are commonly used as guy anchors for utility poles since they are quick to install with a truck mounted hydraulic powered auger drive. A rod with a pivoted blade on the end

236-472: A flagpole; tension from these muscular guy-wires must be provided in all directions to maintain stability in the articulated column formed by the bones of the thumb. Because this stability is actively maintained by muscles rather than by articular constraints, most muscles attached to the thumb tend to be active during most thumb motions. The muscles acting on the thumb can be divided into two groups: The extrinsic hand muscles, with their muscle bellies located in

295-523: A forerunner of Homo sapiens . This, however, is the suggested result of evolution from Homo erectus (around 1 mya ) via a series of intermediate anthropoid stages, and is therefore a much more complicated link. Modern humans are unique in the musculature of their forearm and hand. Yet, they remain autapomorphic, meaning each muscle is found in one or more non-human primates. The extensor pollicis brevis and flexor pollicis longus allow modern humans to have great manipulative skills and strong flexion in

354-539: A long straight section of wire line ends, or angles off in another direction. To protect the public against faults that might allow utility guy cables to become electrified, they usually have a ceramic strain insulator ("Johnny ball") or a fiberglass strain insulator inserted near the top, to keep dangerous voltages away from the lower end. The length near the ground is often encased in a yellow plastic reflector to make it more visible, so that people or vehicles do not run into it. In urban areas with pedestrian traffic around

413-496: A mast collapse. Egg insulators have the porcelain in compression and if it fails, the end loops of the guy wires are still intertwined. AM radio broadcast towers are often fitted with insulators at the mast base and the RF energy is fed at that point. Some are also insulated at the center for feeding the RF energy at that point. Wire rope guys are frequently used and segmented with insulators at several points. Extensive lightning protection

472-406: A medical context, or in a musical context when referring to keyboard instruments. The fourth finger refers to the ring finger (or fourth digit) in a medical context, or in a musical context when referring to keyboard instruments. The fifth finger refers to the pinky finger (or fifth digit) in a medical context, or in a musical context when referring to keyboard instruments. Here, in

531-439: A rotary movement is referred to as circumduction . Primatologists and hand research pioneers John and Prudence Napier defined opposition as: "A movement by which the pulp surface of the thumb is placed squarely in contact with – or diametrically opposite to – the terminal pads of one or all of the remaining fingers." For this true , pulp-to-pulp opposition to be possible, the thumb must rotate about its long axis (at

590-411: A sailboat mast are called "standing rigging" and in modern boats are stainless steel wire rope. Guys are rigged to the bow and stern, usually as a single guy. Lateral guys attach to "chain plates" port and starboard attached to the hull. Multiple guys are usually installed with spreaders to help keep the mast straight ("in column"). Temporary guys are also used. A fore-guy is a line ( rope ) pulling on

649-454: A suffixed form of * penkwe (or * penqe ), which has given rise to many Indo-European -family words (tens of them defined in English dictionaries) that involve, or stem from, concepts of fiveness. The thumb shares the following with each of the other four fingers: The thumb contrasts with each of the other four fingers by being the only one that: and hence the etymology of

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708-424: A terrestrial lifestyle has led to reduced finger length and thus hand proportions similar to those of humans. Consequently, these primates have dexterous hands and are able to grasp objects using a pad-to-pad grip. It can thus be difficult to identify hand adaptations to manipulation-related tasks based solely on thumb proportions. The evolution of the fully opposable thumb is usually associated with Homo habilis ,

767-418: Is a push-brace pole , a diagonal pole with one end set in the ground and the other butting up against the vertica pole, opposite to where a guy cable would attach. Electromagnetic fields from the antennas complicate the design of guys that support mast antennas . Conductive metal guy-wires whose lengths are near to quarter wavelength multiples of the transmitted frequency can distort the radiation pattern of

826-544: Is a human characteristic. Darwinius masillae , an Eocene primate transitional fossil between prosimian and simian , had hands and feet with highly flexible digits featuring opposable thumbs and halluces. Additionally, in many polydactyl cats , both the innermost toe and outermost toe ( pinky ) may become opposable, allowing the cat to perform more complex tasks. In addition to these, some other dinosaurs may have had partially or completely opposed toes in order to manipulate food and/or grasp prey. The skeleton of

885-435: Is driven into the earth. When the guy wire is attached and tensioned, its force pulls the blade open, "setting" it into the soil. These are often used by the military for rapid mast installations. These are used in both soil and rock. A hole is drilled at the angle of the guy. A steel anchor rod with an eye is inserted, and the hole around it is filled with a liquid grout consisting of concrete and an expansion agent or

944-440: Is often possible to use a grounded mast. The power to the guys is fed via wires running from a tuning unit to the feed point on the guys. When operating a crane , guy wires, known as tag lines, may be connected to unwieldy payloads, allowing ground crew to control rotation and swaying while maintaining a safe distance. Guys can be used to raise an extension ladder in a technique called a church raise. In ground-anchored guys,

1003-408: Is required for insulated towers. On antennas for long-wave and VLF, the guys may serve an electrical function, either for capacitive lengthening of the mast or for feeding the mast with the radiation power. In these cases, the guys are fixed without an insulator on the mast, but there is at least one insulator in the guy if necessary. If guys are used for feeding the mast with high frequency power it

1062-463: The ankle or foot that allow humans to walk on two legs". Evidence to date shows that of the 110,000 gene enhancer sequences identified in the human genome , HACNS1 has undergone the most change during the human evolution since the chimpanzee–human last common ancestor . Finger numbering The first finger is an ambiguous term in the English language due to two competing finger numbering systems that can be used. It might refer to either

1121-405: The bi-modality seen in other recessive genetic traits. Other variations of the thumb include brachydactyly type D (which is a thumb with a congenitally short distal phalanx), a triphalangeal thumb (which is a thumb which has 3 phalanges instead of the usual two), and polysyndactyly (which is a combination of radial polydactyly and syndactyly). One of the earlier significant contributors to

1180-413: The carpometacarpal joint ). Arguably, this definition was chosen to underline what is unique to the human thumb. The spider monkey compensates for being virtually thumbless by using the hairless part of its long, prehensile tail for grabbing objects. In apes and Old World monkeys , the thumb can be rotated around its axis, but the extensive area of contact between the pulps of the thumb and index finger

1239-404: The deep branch of the radial nerve (C7-T1). The tendons of the extensor pollicis longus and extensor pollicis brevis form what is known as the anatomical snuff box (an indentation on the lateral aspect of the thumb at its base) The radial artery can be palpated anteriorly at the wrist (not in the snuffbox). There are three thenar muscles : The abductor pollicis brevis (APB) originates on

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1298-401: The four-finger system , as well as in common English, the first finger refers to the index finger (the finger next to the thumb ). This designation carries over in a musical context when referencing the playing of stringed instruments (such as the guitar), woodwind instruments (such as flutes, pipes, or piccolos), and brass instruments (such as horns). The second finger refers to

1357-414: The scaphoid tubercle and the flexor retinaculum . It inserts to the radial sesamoid bone and the proximal phalanx of the thumb. It is innervated by the median nerve (C8-T1). The flexor pollicis brevis (FPB) has two heads. The superficial head arises on the flexor retinaculum, while the deep head originates on three carpal bones: the trapezium , trapezoid , and capitate . The muscle is inserted onto

1416-439: The thumb or the index finger , depending on the context. The second finger is another ambiguous term in English. It might refer to either the index finger or the middle finger , also dependent on context. The same can be said for the third finger (referring to either the middle finger or the ring finger ); and the fourth finger (referencing either the ring finger or the pinky ). The fifth finger will exclusively refer to

1475-585: The anatomical basis of hand movement. Napier proposed two primary prehensile grips: the precision grip and the power grip . The precision and power grip are defined by the position of the thumb and fingers where: Opposability of the thumb should not be confused with a precision grip as some animals possess semi-opposable thumbs yet are known to have extensive precision grips ( Tufted Capuchins for example). Nevertheless, precision grips are usually only found in higher apes, and only in degrees significantly more restricted than in humans. The pad-to-pad pinch between

1534-460: The antenna. This also applies to guy wires of neighboring masts or nearby metal structures. To prevent this, each guy wire is divided by strain insulators into multiple sections, each segment non-resonant at the transmitted wavelength. Cylindrical or egg-shaped porcelain "Johnny ball" insulators (also called "egg insulators") are usually used. Non-conductive guys of Kevlar fiber (Phillystran) or extruded fiberglass rod are frequently used to not disturb

1593-440: The base of the distal phalanx of the thumb. It is innervated by the anterior interosseus branch of the median nerve (C7-C8) It is a persistence of one of the former contrahentes muscles that pulled the fingers or toes together. Three dorsal forearm muscles act on the thumb: The abductor pollicis longus (APL) originates on the dorsal sides of both the ulna and the radius, and from the interosseous membrane. Passing through

1652-445: The dorsal side of the ulna and the interosseous membrane. Passing through the third tendon compartment, it is inserted onto the base of the distal phalanx of the thumb. It uses the dorsal tubercle on the lower extremity of the radius as a fulcrum to extend the thumb and also dorsiflexes and abducts the hand at the wrist. It is innervated by the deep branch of the radial nerve (C7-C8). The extensor pollicis brevis (EPB) originates on

1711-402: The electrical wires at a spot where the wires change direction. Conductive guy cables for radio antenna masts can catch and deflect radiation in unintended directions, so their electrical characteristics must be included in the design. Often the guy wire is divided by strain insulators into isolated sections whose lengths are not resonant with the transmission frequencies. The guys supporting

1770-432: The first and second (proximal and distal) phalanges varies between 0° and almost 90° when the thumb is in a thumbs-up gesture. It has been suggested that the variation is an autosomal recessive trait , called a hitchhiker's thumb , with homozygous carriers having an angle close to 90°. However this theory has been disputed, since the variation in thumb angle is known to fall on a continuum and shows little evidence of

1829-399: The first metacarpal. It opposes the thumb and assists in adduction. It is innervated by the median nerve . Other muscles involved are: The adductor pollicis also has two heads. The transversal head originates along the entire third metacarpal bone, while the oblique head originates on the carpal bones proximal to the third metacarpal. The muscle is inserted onto the ulnar sesamoid bone of

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1888-443: The first tendon compartment, it inserts to the base of the first metacarpal bone . A part of the tendon reaches the trapezium, while another fuses with the tendons of the extensor pollicis brevis and the abductor pollicis brevis. Except for abducting the hand, it flexes the hand towards the palm and abducts it radially. It is innervated by the deep branch of the radial nerve (C7-C8). The extensor pollicis longus (EPL) originates on

1947-446: The forearm, and the intrinsic hand muscles, with their muscle bellies located in the hand proper. A ventral forearm muscle, the flexor pollicis longus (FPL) originates on the anterior side of the radius distal to the radial tuberosity and from the interosseous membrane . It passes through the carpal tunnel in a separate tendon sheath , after which it lies between the heads of the flexor pollicis brevis. It finally attaches onto

2006-476: The free end of a spar . On a modern sloop -rigged sailboat with a symmetric spinnaker , the spinnaker pole is the spar most commonly controlled by one or more guys. Utility poles are buried in the ground and have sufficient strength to stand on their own; guys are needed on some poles only to support unbalanced lateral loads from the utility wires attached to them, or to resist ground movement. Guys are particularly needed on dead-end ( anchor ) poles, where

2065-421: The grasping hand, the distal pads can therefore conform to uneven surfaces while pressure is distributed more evenly in the finger tips. The distal pad of the human thumb is divided into a proximal and a distal compartment, the former more deformable than the latter, which allows the thumb pad to mold around an object. In robotics, almost all robotic hands have a long and strong opposable thumb. Like human hands,

2124-408: The metacarpophalangeal joint. It adducts the thumb, and assists in opposition and flexion. It is innervated by the deep branch of the ulnar nerve (C8-T1). The first dorsal interosseous , one of the central muscles of the hand, extends from the base of the thumb metacarpal to the radial side of the proximal phalanx of the index finger. There is a variation of the human thumb where the angle between

2183-520: The middle finger in common English, or when playing string, brass, or woodwind instruments in music. The third finger refers to the ring finger in common English, or in a musical context when referring to string, brass, or woodwind instruments. The fourth finger refers to the pinky (or little) finger in common English, or in a musical context when referring to string, brass, or woodwind instruments. Guy-wire A guy-wire , guy-line , guy-rope , down guy , or stay , also called simply

2242-445: The motor sequencing of the thumb. A primitive autonomization of the first carpometacarpal joint (CMC) may have occurred in dinosaurs. A real differentiation appeared an estimated 70 mya in early primates, while the shape of the human thumb CMC finally appears about 5 mya. The result of this evolutionary process is a human CMC joint positioned at 80° of pronation, 40 of abduction, and 50° of flexion in relation to an axis passing through

2301-404: The other is anchored to the ground at some distance from the mast or tower base. The tension in the diagonal guy-wire, combined with the compression and buckling strength of the structure, allows the structure to withstand lateral loads such as wind or the weight of cantilevered structures. They are installed radially , usually at equal angles about the structure, in trios and quads. As

2360-461: The pinky, (also called the little finger). The ordinal numbers of the fingers of the human hand are numbered ambiguously in the English language. This is due to two competing finger numbering systems that can be used. For instance, the first finger might refer to either the thumb or the index finger, depending on the context. In the Five-finger system , the first finger usually refers to

2419-408: The plate anchor, in which the guy is attached to a rod with an eyelet extending from the center of a steel plate buried diagonally, perpendicular to the angle of the guy. In the concrete anchor, a diagonal rod with an eyelet extending in the guy direction is cemented into a hole filled with steel reinforced concrete. A sufficiently massive concrete block on the surface of the ground can also be used as

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2478-420: The pole, a variation called a sidewalk guy is often used: the guy line extends diagonally from the top of the pole to a spar brace extending out from the middle of the pole, then continues vertically to the ground. Thus, the bottom length of the guy is vertical and does not obstruct headroom, so a sidewalk can pass between the pole and the guy. An alternative to guy-wires sometimes used on dead-end utility poles

2537-412: The radial sesamoid bone of the metacarpophalangeal joint. It acts to flex, adduct, and abduct the thumb, and is therefore also able to oppose the thumb. The superficial head is innervated by the median nerve , while the deep head is innervated by the ulnar nerve (C8-T1). The opponens pollicis originates on the tubercle of the trapezium and the flexor retinaculum. It is inserted onto the radial side of

2596-462: The radiation pattern of the antennas. The strength and low stretch properties of Kevlar fiber approaches that of steel. However, Kevlar is very susceptible to ultraviolet degradation, so it is enclosed in a UV resistant plastic sheath. The individual sections of conductive guys can develop large charges of static electricity , especially on very tall masts. The voltage caused by this static electricity can be several times larger than that generated by

2655-432: The second and third CMC joints. Opposable thumbs are shared by some primates , including most catarrhines . The climbing and suspensory behaviour in orthograde apes, such as chimpanzees , has resulted in elongated hands while the thumb has remained short. As a result, these primates are unable to perform the pad-to-pad grip associated with opposability. However, in pronograde monkeys such as baboons , an adaptation to

2714-431: The soil to resist the forces from all of the guys attached to it. Several types of anchor are used: In this type, a hole is excavated and an object with a large surface area is placed in it with the guy wire attached, and the hole is backfilled with earth or concrete. In the historical form of dead man anchor, a log is buried horizontally in a trench with the guy attached perpendicularly to its center. Modern forms are

2773-426: The structure which attaches the guy-wire to the ground is called an anchor . The anchor must be adequate to resist the maximum tensile load of the guy wires; both the dead load of the tension of the wire and the maximum possible live load due to wind. Since the guy wire exerts its force at an angle, the anchor has both vertical and lateral (horizontal) forces on it. The anchor relies on the lateral shear strength of

2832-411: The study of hand grips was orthopedic primatologist and paleoanthropologist John Napier , who proposed organizing the movements of the hand by their anatomical basis as opposed to work done earlier that had only used arbitrary classification. Most of this early work on hand grips had a pragmatic basis as it was intended to narrowly define compensable injuries to the hand, which required an understanding of

2891-415: The thumb (or first digit) in a medical context, or in a musical context when referring to playing keyboard instruments , such as the piano or accordion. The second finger under this system will refer to the index finger (or second digit) in medicine, or in a musical context when referencing the playing of keyboard instruments. The third finger usually refers to the middle finger (or third digit) in

2950-416: The thumb and index finger is made possible because of the human ability to passively hyperextend the distal phalanx of the index finger. Most non-human primates have to flex their long fingers in order for the small thumb to reach them. In humans, the distal pads are wider than in other primates because the soft tissues of the finger tip are attached to a horseshoe-shaped edge on the underlying bone, and, in

3009-443: The thumb consists of the first metacarpal bone which articulates proximally with the carpus at the carpometacarpal joint and distally with the proximal phalanx at the metacarpophalangeal joint . This latter bone articulates with the distal phalanx at the interphalangeal joint . Additionally, there are two sesamoid bones at the metacarpophalangeal joint. The muscles of the thumb can be compared to guy-wires supporting

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3068-467: The thumb of a robotic hand also plays a key role in gripping an object. One inspiring approach of robotic grip planning is to mimic human thumb placement. In a sense, human thumb placement indicates which surface or part of the object is good for grip. Then the robot places its thumb to the same location and plans the other fingers based on the thumb placement. The function of the thumb declines physiologically with aging. This can be demonstrated by assessing

3127-465: The thumb. However, a more likely scenario may be that the specialized precision gripping hand (equipped with opposable thumb) of Homo habilis preceded walking, with the specialized adaptation of the spine, pelvis, and lower extremities preceding a more advanced hand. And, it is logical that a conservative, highly functional adaptation be followed by a series of more complex ones that complement it. With Homo habilis , an advanced grasping-capable hand

3186-399: The tower leans a bit due to the wind force, the increased guy tension is resolved into a compression force in the tower or mast and a lateral force that resists the wind load. For example, antenna masts are often held up by three guy-wires at 120° angles. Structures with predictable lateral loads, such as electrical utility poles, may require only a single guy-wire to offset the lateral pull of

3245-403: The transition between flexion-abduction and extension-adduction; the side of the distal thumb phalanx thus approximated to the palm or the hand's radial side (side of index finger) during apposition and the pulp or "palmar" side of the distal thumb phalanx approximated to either the palm or other fingers during opposition . Moving a limb back to its neutral position is called reposition and

3304-476: The transmitter. In order to avoid dangerous and unpredictable discharges, the insulators must be designed to withstand this high voltage, which on tall masts results in over-dimensioned backstage insulators. At each backstage insulator, a lightning arrestor in the form of an arc gap is required for the purpose of over-voltage protection in case of lightning strikes. The insulators and arrestors must be maintained carefully, because an insulator failure can result in

3363-399: The ulna distal to the abductor pollicis longus, from the interosseus membrane, and from the dorsal side of the radius. Passing through the first tendon compartment together with the abductor pollicis longus, it is attached to the base of the proximal phalanx of the thumb. It extends the thumb and, because of its close relationship to the long abductor, also abducts the thumb. It is innervated by

3422-686: The word: * tum is Proto-Indo-European for 'swelling' (cf 'tumor' and 'thigh') since the thumb is the stoutest of the fingers. Anatomists and other researchers focused on human anatomy have hundreds of definitions of opposition . Some anatomists restrict opposition to when the thumb is approximated to the fifth finger (little finger) and refer to other approximations between the thumb and other fingers as apposition . To anatomists, this makes sense as two intrinsic hand muscles are named for this specific movement (the opponens pollicis and opponens digiti minimi respectively). Other researchers use another definition, referring to opposition-apposition as

3481-464: Was accompanied by facultative bipedalism , possibly implying, assuming a co-opted evolutionary relationship exists, that the latter resulted from the former as obligate bipedalism was yet to follow. Walking may have been a by-product of busy hands and not vice versa. HACNS1 (also known as Human Accelerated Region 2) is a gene enhancer "that may have contributed to the evolution of the uniquely opposable human thumb, and possibly also modifications in

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