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

The hands (med./lat.: manus, pl. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. In the Circulatory system, a vein is a Blood vessel that carries Blood back toward the Heart (as opposed to Artery, a blood vessel The dorsal venous network of the hand is a network of veins formed by the Dorsal metacarpal veins. A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. In Human anatomy, the ulnar nerve is a nerve which runs near the Ulna bone The median nerve is a Nerve that runs down the Arm and Forearm. The radial nerve is a Nerve in the human body that supplies the Triceps brachii muscle of the arm as well as all 12 muscles in the Posterior osteofascial compartment Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. manūs) are the two intricate, prehensile, multi-fingered body parts normally located at the end of each arm of a human or other primate. A finger is a type of digit, an organ of manipulation and sensation found in the Hands of Humans and other Primates Normally humans have five digits Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus A primate is a member of the biological order Primates ( Latin: "prime first rank" the group that contains Lemurs the Aye-aye They are the chief organs for physically manipulating the environment, using anywhere from the roughest motor skills (wielding a club) to the finest (threading a needle), and since the fingertips contain some of the densest areas of nerve endings on the human body, they are also the richest source of tactile feedback so that sense of touch is intimately associated with human 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. Handedness is an attribute of human beings defined by their unequal distribution of Fine motor skill between the left and right Hands.

Contents 1 What constitutes a hand? 2 Anatomy of the human hand 2.1 Digits 2.2 Bones 2.3 Articulations 2.4 Muscles and tendons 2.5 Variation 3 Additional images 4 See also 5 References 6 External links

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 hands. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands paw is the soft Foot of a Mammal, generally a Quadruped, that has Claws or nails A claw is a curved pointed appendage found at the end of a toe or finger in most Mammals, Birds, and some Reptiles. The scientific use of the term hand to distinguish the terminations of the front paws from the hind ones is an example of anthropomorphism. Anthropomorphism is the attribution of uniquely Human characteristics to non-human creatures and beings natural and supernatural phenomena material states and objects The only true hands appear in the mammalian order of primates. A primate is a member of the biological order Primates ( Latin: "prime first rank" the group that contains Lemurs the Aye-aye Hands must also have opposable thumbs, as described later in the text. The thumb is the medial -most digit of the hand The English adjective for thumb is pollical

Humans have only two hands (except in cases of polymelia),^[1] which are attached to the arms. Polymelia (from Greek πολυ- = "many" plus μέλος (plural μέλεα = "limb" is a Birth defect involving limbs (a type of Dysmelia) 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. A monkey is any member of either the New World monkeys or Old World monkeys two of the three groupings of Simian Primates the third group being The hallux, commonly referred to as the big toe (also as great toe or thumb toe) even though it's not actually the biggest toe on the foot of some The thumb is the medial -most digit of the hand The English adjective for thumb is pollical Also, some apes have toes that are longer than human fingers[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). ^[2][3] 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. A finger is a type of digit, an organ of manipulation and sensation found in the Hands of Humans and other Primates Normally humans have five digits Each finger, starting with the one closest to the thumb, has a colloquial name to distinguish it from the others:

• index finger (med./lat.:digitus secundus manus), pointer finger, or forefinger
• middle finger (med./lat.:digitus me´dius)
• ring finger (med./lat.:digitus annula´ris)
• little finger (med./lat.:digitus mi´nimus ma´nus) or 'pinky'

The thumb (connected to the trapezium) is located on one of the sides, parallel to the arm. The second Digit of a human Hand is also referred to as the index finger, pointer finger, forefinger, trigger finger, digitus Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. The middle finger (or the long finger) is the third digit of the human Hand and usually the longest Finger, located between the Index finger Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. The ring finger is the fourth digit of the human Hand, and the second most Ulnar Finger, located between the Middle finger and the Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. The little finger, often called the pinky in American English and pinkie in Scottish English (from the Dutch word pink Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. The thumb is the medial -most digit of the hand The English adjective for thumb is pollical The trapezium bone ( greater multangular bone) is a carpal bone in what is commonly referred to as the Wrist. 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°. A reliable way of identifying true hands is from the presence of opposable thumbs. The thumb is the medial -most digit of the hand The English adjective for thumb is pollical Opposable thumbs are identified by the ability to be brought opposite to the fingers, a muscle action known as opposition. The movement of body structures is accomplished by the contraction of Muscles Muscles may move parts of the skeleton relatively to each other or may move parts of internal organs relatively

Bones

Main article: phalanx 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, your fingers and thumb. In Tetrapods the carpus is the sole cluster of the Bones in the Wrist between the radius and Ulna and the Metacarpus The metacarpus is the intermediate part of the Hand Skeleton that is located between the Phalanges (bones of the fingers Distally and the 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 scaphoid bone (hand navicular of the Wrist is found on the Thumb side of the hand within the Anatomical snuffbox. The lunate bone ( semilunar bone) is a Carpal bone (wrist bone in the Human Hand that may be distinguished by its deep concavity and crescentic The triquetral bone (also called triquetrum bone, cuneiform bone, pyramidal bone, cubital bone, three-cornered bone, and triangular The pisiform bone (also called pisiform or lentiform bone) is a small knobbly pea-shaped Wrist bone

The bones of the distal row are (from lateral to medial): trapezium, trapezoid, capitate and hamate. The trapezium bone ( greater multangular bone) is a carpal bone in what is commonly referred to as the Wrist. The trapezoid bone ( lesser multangular bone) is a carpal bone in Tetrapods including humans The capitate bone is a Bone in the Human Hand. The capitate bone is the largest of the Carpal bones and occupies the center of the wrist The hamate bone ( unciform bone) is a Bone in the Human Hand that may be readily distinguished by its wedge-shaped form and the hook-like process The palm has 5 bones (metacarpals), one to each of the 5 digits. The metacarpus is the intermediate part of the Hand Skeleton that is located between the Phalanges (bones of the fingers Distally and the These metacarpals have a head and a shaft.

Human hands contain 14 digital bones, also called 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. In Anatomy, a sesamoid bone is a Bone embedded within a Tendon. Ossification is the process of Bone formation in which connective tissues such as Cartilage are turned to bone or bone-like 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. A gesture is a form of Non-verbal communication made with a part of the body used instead of or in combination with verbal communication.

The articulations are:

• interphalangeal articulations of hand
• metacarpophalangeal joints
• intercarpal articulations
• wrist (may also be viewed as belonging to the forearm. The interphalangeal articulations of hand are Hinge-joints of the Phalanges of the hand. The metacarpophalangeal joints (MCP are of the Condyloid kind formed by the reception of the rounded heads of the Metacarpal bones into shallow cavities on the The intercarpal articulations ( articulations of the Carpus) can be subdivided into three sets of articulations Those of the proximal row of carpal bones those of In Human anatomy, the wrist is the flexible and narrower connection between the Forearm and the palm. The forearm is the structure on the Upper limb, between the elbow and the Wrist. )

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. The thenar eminence is the body of Muscle on the palm of the human Hand just beneath the Thumb. Hypothenar refers to a group of three muscles of the palm that control the motion of the Little finger. The dorsal interossei of the hand are muscles that occupy the space between the Metacarpals. The palmar interossei ( interossei volares) are small muscles in the hand that lie on the anterior aspect of the Metacarpals. The lumbrical muscles are intrinsic Muscles in the Fingers that allow flexion at the Metacarpophalangeal joints while maintaining extension at the interphalangeal These muscles arise from the deep flexor (and are special because they have no bony origin) and insert on the dorsal extensor hood mechanism. In Human anatomy, the flexor digitorum profundus is a Muscle in the Forearm that flexes the Fingers It is considered to be an Extrinsic

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. Abduction, in functional anatomy is a movement which draws a limb away from the median ( Sagittal) plane of the body

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. The anatomical snuffbox, or radial fossa, (in Latin Foveola radialis) is a triangular deepening on the radial, dorsal aspect of the hand - at 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

Some people have more than the usual number of fingers or toes, a condition called polydactyly. Polydactyly or polydactylism (from Ancient Greek πολύς (polus "many" + δάκτυλος (daktulos ^[4] Others may have more than the typical number of metacarpal bones, a condition often caused by genetic disorders like Catel-Manzke syndrome. Catel-Manzke syndrome is a rare Genetic disorder characterized by distinctive abnormalities of the index fingers the classic features of Pierre Robin syndrome; occasionally The average length of an adult male hand is 189 mm, while the average length of an adult female hand is 172 mm. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to The average hand breadth for adult males and females is 84 and 74 mm respectively. ^[5]

Additional images

See also

• Hand strength
• Dermatoglyphics
• Digit ratio
• Handanalysis
• Hand fetishism
• Handstand
• Hand walking
• Pentadactyl limb
• Reflexology
• Handedness

References

External links

• Hand injuries and diseases (Handuniversity.com)
• Hand anatomy (eMedicine)
• Interesting facts about the hands

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