Anatomical structure of the hand. Hand: structural features and functions. Ligaments and muscles

The bones of the arms and hands perform important functions of supporting the upper limbs and providing attachment for the muscles that move the upper limbs. These bones form joints that allow a wide range of motion and the flexibility needed to dexterously manipulate objects using arm strength. They also provide strength to withstand the extreme stresses placed on the shoulders and arms during sports, training and heavy labor... [Read below]

Shoulder joint
Brachial bone
Elbow joint
Radius
Elbow bone
Hand bones

[Start at the top] ... Consisting of the collarbones and shoulder blades, the shoulder girdle forms the point of attachment between the arms and the rib cage. The collarbone, which gets its name from the Latin word clavicula, is a long bone that connects the shoulder blade to the sternum (breastbone) of the chest. It is located under the skin in the chest area between the shoulder and the base of the neck. The collarbone is slightly curved, like the letter S, and is about fifteen centimeters in length. Two joints formed by the clavicle - in the sternoclavicular joint with the sternum, and in the acromioclavicular joint with the acromion of the scapula. The collarbones allow the shoulder joint to move in a circle while remaining attached to the bones of the rib cage.

Posterior to the collarbone is the scapula, a triangular-shaped, flat bone located lateral to the thoracic spine in the dorsal region of the body. The shoulder blades form joints in two places: the acromioclavicular joint - the clavicle and shoulder joint, and the clavicle with the humerus. The glenoid cavity is located on the lateral end of the scapula and forms a socket for the shoulder joint. Many muscles attach to the scapula to move the shoulder, including the trapezius, deltoid, rhomboid, and rotator cuff muscles.

Humerus

- these are only the bones of the upper arm. Long, large bones that extend from the shoulder blade to the ulna and radius bones in the forearm. The proximal end of the humerus is a circular structure that forms the ball for the shoulder joint. At the distal end, the humerus forms a broad, cylindrical structure that forms the internal hinge of the elbow joint from the ulna and radius. The pectoralis, deltoids, latissimus dorsi, and rotator cuff muscles attach to the humerus to rotate, raise, and lower the arm at the shoulder joint.

The forearms contain two long, parallel bones: the ulna and the radius. The ulna is the longer and larger of the two bones, located on the medial (little finger side) side of the forearm.
The widest area is at its proximal end and significantly narrowed at the distal end. At the proximal end of the ulna there is a hinge of the elbow joint with the humerus. The end of the ulna, known as the olecranon, extends onto the humerus and forms the bony tip of the elbow. At its distal end, the ulna forms the radiocarpal joint with the radial and carpal joints.

Compared to the ulna, the radius is slightly shorter, thinner, and located on the lateral side of the forearm. The radius is narrowest at the elbow and widens towards the wrist. At its proximal end, the rounded heads of the radius form the rotating portion of the elbow joint, which allows rotation of the forearm and hand. At the distal end, it is much wider than the ulna and forms the bulk of the wrist joint and with the ulna forms the carpal joint. The distal end of the radius also rotates around the ulna when the arm and forearm rotate.

Despite their small size, the arms contain twenty-seven small bones and many flexible joints.

The carpal joints are a group of eight cuboid bones. They form the wrist joint with the ulna and radius bones of the forearm, and also form the wrist joints in the palm. The wrist joints form many small joints, sliding together to give additional flexibility to the wrist and hand.

Five long, cylindrical metacarpal bones support the shape of the palm. Each metacarpal bone forms a joint with the wrist and another joint with the proximal phalanx of the finger. The metacarpal bones also give flexibility to the hands when grasping an object or pressing the thumb and little finger together.

Phalanx

They are a group of fourteen bones that support and move the fingers. Each finger contains up to three phalanges - distal, middle and proximal - with the exception of the thumb, which contains only the proximal and distal phalanges.

The phalanges of the long bones form articulated joints with each other, as well as the condyle of the joints with the metacarpal bones. These sutures allow flexion, extension, abduction and adduction of the fingers.
The arms require a balance of strength and dexterity to perform a variety of tasks, such as lifting heavy objects, swimming, playing a musical instrument, and being able to write.
Arm joints and muscles provide a wide range of motion while maintaining upper extremity strength. Like all bones in the body, the bones of the upper limb help the body maintain homeostasis by storing minerals and fats and producing blood cells in the red bone marrow.

The hand and fingers are the main tools in any work. A decrease in their functionality largely leads to a decrease in working capacity and to a limitation of human capabilities.

Joints and bones of the hand

The anatomy of the human hand is distinguished by the presence of small bones articulated by joints of various types. There are three components of the hand: the wrist, the metacarpal part, and the phalanges of the fingers. The wrist in common parlance is called the wrist joint, but from an anatomical point of view it is the proximal part of the hand. It consists of 8 bones arranged in two rows.

The first proximal row consists of three bones connected by fixed joints. Adjacent to it on the outer side is a pisiform bone, inherited from distant ancestors and used to enhance muscle strength (one of the sesamoid bones). The bony surface of the first row, facing the bones of the forearm, forms a single articular surface for connection with the radius.

Bones of the hand

The second row of bones is represented by four bones that connect distally to the metacarpus. The carpal part is shaped like a small boat, where the palmar surface is its concave part. The space between the bones is filled with articular cartilage, connective tissue, nerves and blood vessels. Movements in the wrist itself and movement of its bones relative to each other are almost impossible. But thanks to the presence of a joint between the carpal part and the radius, a person can rotate the hand, adduct it and abduct it.

Joints of the hand

The metacarpal part consists of five tubular bones. Their proximal part is connected to the wrist by fixed joints, and the distal part is connected to the proximal phalanges of the fingers by movable joints. The metacarpophalangeal joints are ball-and-socket joints. They enable flexion, extension and rotational movements.

The thumb joint is saddle-shaped and provides only extension and flexion. Each finger is represented by three phalanges, connected through movable trochlear joints. They perform flexion and extension of the fingers. All hand joints have durable articular capsules. Sometimes the capsule can unite 2-3 joints. To strengthen the osteoarticular frame, there is a ligamentous apparatus.

Ligaments of the hand

The joints of the human hand are held and protected by a whole complex of ligaments. They have increased elasticity and at the same time strength due to very dense connective tissue fibers. Their function is to ensure movement in the joints no more than the physiological norm, to protect them from injury. In cases of increased physical effort (falls, heavy lifting), the ligaments of the hand can still be stretched; cases of rupture are very rare.

The ligamentous apparatus of the hand is represented by numerous ligaments: interarticular, dorsal, palmar, collateral. The palmar part of the hand is covered by the flexor retinaculum. It forms a single channel in which the tendons of the digital flexor muscle pass. The palmar ligaments run in different directions, creating a thick fibrous layer; there are fewer dorsal ligaments.

The metacarpophalangeal and interphalangeal joints are strengthened by lateral collateral ligaments and also have additional ones on the palmar surface. The flexor retinaculum on the palm and the extensor retinaculum on the dorsum are involved in creating fibrous sheaths for these muscles. Thanks to them and the synovial spaces, the tendons are protected from external influences.

Muscles of the hand

When studying the anatomy of the human hand, one cannot help but pay attention to the perfection of its muscular apparatus. All the smallest and precise movements of the fingers would be impossible without the coordinated work of all the wrist muscles. All of them are located only on the palm; the extensor tendon runs on the back side. According to their location, the muscles of the hand can be divided into three groups: the muscles of the thumb, the middle group and the small finger.

Muscles and tendons of the hand

The middle group is represented by interosseous muscles that connect the bones of the metacarpal part, and worm-shaped muscles that are attached to the phalanges. The interosseous muscles bring and spread the fingers, and the lumbrical muscles bend them at the metacarpophalangeal joints. The muscle group of the thumb makes up the so-called thenar, the eminence of the thumb. They bend and unbend, abduct and adduct.

The hypotenar, or eminence of the lesser finger (little finger), is located on the other side of the palm. The muscle group of the small finger opposes, abducts and adducts, flexes and extends. Movement of the hand in the wrist joint is provided by the muscles located on the forearm due to the attachment of their tendons to the bones of the hand.

Muscles and tendons

Blood supply and innervation of the hand

The bones and joints, muscles and ligaments of the hand are literally riddled with blood vessels. The blood supply is very well developed, which ensures high differentiation of movements and rapid tissue regeneration. Two arteries, the ulnar and radial, approach the hand from the forearm, and, passing through special channels through the wrist joint, they end up between the muscles and bones of the hand. Here an anastomosis (connection) is formed between them in the form of a deep and superficial arc.

Smaller arteries extend from the arches to the fingers; each finger is supplied with blood by four vessels. These arteries also connect with each other, forming a network. This branched type of vessels helps with injuries when, if any branch is damaged, the blood supply to the fingers suffers slightly.

Arteries of the hand

The ulnar, radial and median nerves, passing through all elements of the hand, end on the fingertips with a huge number of receptors. Their function is to provide tactile, temperature and pain sensitivity.

Nerves of the hand

Coordinated and harmonious work of the hand is possible only if the functionality of all its components is preserved. A healthy hand is necessary for a person to live a full life and maintain his ability to work.

Anatomy of the hand

If we consider the hand as a whole, then, as in any other part of the human musculoskeletal system, three main structures can be distinguished: the bones of the hand; ligaments of the hand, which hold the bones and form joints; muscles of the hand.

Hand bones

The hand has three sections: wrist, metacarpus and fingers.

Carpal bones

The eight small bones of the wrist have an irregular shape. They are located in two rows.

The proximal row of carpal bones forms an articular surface convex towards the radius. The distal row is connected to the proximal row using an irregularly shaped joint.

The bones of the wrist lie in different planes and form a groove (carpal groove) on the palmar surface and a bulge on the back. The groove of the wrist contains the tendons of the finger flexor muscles. Its inner edge is limited by the pisiform bone and the hook of the hamate bone, which are easily palpable; the outer edge is composed of two bones - the scaphoid and the polygonal.

Metacarpal bones

The metacarpus consists of five tubular metacarpal bones. The metacarpal bone of the first finger is shorter than the others, but is distinguished by its massiveness. The longest is the second metacarpal bone. The following bones towards the ulnar edge of the hand decrease in length. Each metacarpal bone has a base, a body and a head.

The bases of the metacarpal bones articulate with the bones of the wrist. The bases of the first and fifth metacarpal bones have saddle-shaped articular surfaces, and the rest have flat articular surfaces. The heads of the metacarpal bones have a hemispherical articular surface and articulate with the proximal phalanges of the fingers.

Finger bones

Each finger consists of three phalanges: proximal, middle and distal. The exception is the first finger, which has only two phalanges - proximal and distal. The proximal phalanges are the longest, the distal ones are the shortest. Each phalanx has a middle part - a body and two ends - proximal and distal. At the proximal end is the base of the phalanx, and at the distal end is the head of the phalanx. At each end of the phalanx there are articular surfaces for articulation with adjacent bones.

Sesamoid bones of the hand

In addition to these bones, the hand also has sesamoid bones, which are located in the thickness of the tendons between the metacarpal bone of the thumb and its proximal phalanx. There are also unstable sesamoid bones between the metacarpal bone and the proximal phalanx of the second and fifth fingers. Sesamoid bones are usually located on the palmar surface, but are occasionally found on the dorsal surface. The sesamoid bones also include the pisiform bone. All sesamoid bones, as well as all processes of bones, increase the leverage of the muscles that are attached to them.

Ligamentous apparatus of the hand

Wrist joint

The formation of this joint involves the radius and bones of the proximal row of the wrist: scaphoid, lunate and triquetrum. The ulna does not reach the surface of the radiocarpal joint (it is “supplemented” by the articular disc). Thus, in the formation of the elbow joint, the ulna plays the largest role of the two forearm bones, and the radius plays the largest role in the formation of the radiocarpal joint.

In the radiocarpal joint, which has an elliptical shape, flexion and extension, adduction and abduction of the hand are possible. Pronation

Antonym - medial edge. .

Movements in the radiocarpal joint are closely related to movements in the midcarpal joint, which is located between the proximal and distal rows of carpal bones. This joint has a complex, irregularly shaped surface. The total range of mobility when flexing the wrist reaches 85°, and when extending it is also approximately 85°. Adduction of the hand in these joints is possible by 40°, and abduction by 20°. In addition, circular movement (circumduction) is possible in the radiocarpal joint.

The radiocarpal and midcarpal joints are strengthened by numerous ligaments. The ligamentous apparatus of the hand is very complex. Ligaments are located on the palmar, dorsal, medial

Antonym - lateral edge. .

Carpometacarpal joints of the hand

They are connections of the distal row of carpal bones with the bases of the metacarpal bones. These joints, with the exception of the carpometacarpal joint of the thumb, are flat and inactive. The range of movements in them does not exceed 5-10°. Mobility in these joints, as well as between the bones of the wrist, is sharply limited by well-developed ligaments.

The ligaments located on the palmar surface of the hand make up a strong palmar ligamentous apparatus. It connects the carpal bones to each other, as well as to the metacarpal bones. On the hand you can distinguish ligaments that run arcuate, radial and transverse. The central bone of the ligamentous apparatus is the capitate, to which more ligaments are attached than to any other bone of the wrist. The dorsal ligaments of the hand are much less developed than the palmar ligaments. They connect the bones of the wrist to each other, making up thickening capsules covering the joints between these bones. In addition to the palmar and dorsal ligaments, the second row of carpal bones also has interosseous ligaments.

Due to the fact that the bones of the distal row of the wrist and the four (II-V) bones of the metacarpus are inactive relative to each other and are firmly connected into a single formation that makes up the central bone core of the hand, they are designated as the solid base of the hand.

Metacarpophalangeal joints of the hand

Formed by the heads of the metacarpal bones and the bases of the proximal phalanges of the fingers. All these joints have a spherical shape and, accordingly, three mutually perpendicular axes of rotation, around which flexion and extension, adduction and abduction, as well as circular movement (circumduction) occur. Flexion and extension are possible at 90-100°, abduction and adduction - at 45-50°.

The metacarpophalangeal joints are strengthened by collateral ligaments located on the sides of them. On the palmar side, the capsules of these joints have additional ligaments called palmar ligaments. Their fibers are intertwined with the fibers of the deep transverse metacarpal ligament, which prevents the heads of the metacarpal bones from diverging to the sides.

Interphalangeal joints of the hand

They have a block-like shape, their axes of rotation run transversely. Flexion and extension are possible around these axes. Their volume in the proximal interphalangeal joints is 110-120°, while in the distal ones it is 80-90°. All interphalangeal joints are strengthened by well-defined collateral ligaments.

Fibrous and synovial sheaths of the tendons of the fingers

The flexor retinaculum and extensor retinaculum ligaments are of great importance for strengthening the position of the muscle tendons passing under them, especially when flexing and extending the hand: the tendons rest on the named ligaments from their inner surface, and the ligaments prevent the tendons from moving away from the bones and withstand significant pressure during strong muscle contractions .

Special tendon sheaths, which are fibrous or osteo-fibrous canals, inside of which there are synovial sheaths, promote the sliding of the muscle tendons passing from the forearm to the hand and the reduction of friction.

The palmar synovial sheaths belong to the flexor tendons of the hand and fingers running in the carpal canal. The tendons of the superficial and deep flexor fingers lie in a common synovial sheath, which extends to the middle of the palm, reaching the distal phalanx of only the fifth finger, and the tendon of the flexor pollicis longus is located in a separate synovial sheath, which passes along with the tendon onto the finger. In the palm area, the tendons of the muscles going to the second, third and fourth fingers are deprived of synovial sheaths for some distance and receive them again on the fingers. Only the tendons leading to the fifth finger have a synovial sheath, which is a continuation of the common synovial sheath for the flexor tendons of the fingers.

Muscles of the hand

On the hand, the muscles are located only on the palmar side. Here they form three groups: the middle one (in the middle section of the palmar surface), the thumb muscle group and the small finger muscle group. The large number of short muscles on the hand is due to the fine differentiation of finger movements.

Middle hand muscle group

Consists of lumbrical muscles that originate from the tendons of the deep flexor digitorum and are attached to the base of the proximal phalanges of the second to fifth fingers; palmar and dorsal interosseous muscles, which are located in the interosseous spaces between the metacarpal bones and are attached to the base of the proximal phalanges of the second to fifth fingers. The function of the muscles of the middle group is that they are involved in flexing the proximal phalanges of these fingers. In addition, the palmar interosseous muscles bring the fingers of the hand towards the middle finger, and the dorsal interosseous muscles spread them apart.

Thumb muscle group

Forms the so-called eminence of the thumb on the hand. They begin on the nearby bones of the wrist and metacarpus. Among them are distinguished: the short muscle that abducts the pollicis, which is attached to its proximal phalanx; flexor pollicis brevis, which attaches to the external sesamoid bone located at the base of the proximal phalanx of the thumb; the opponus pollicis muscle, which goes to the first metacarpal bone; and the adductor pollicis muscle, which attaches to the internal sesamoid bone located at the base of the proximal phalanx of the thumb. The function of these muscles is indicated in the name of each muscle.

Small finger muscle group

Forms an elevation on the inside of the palm. This group includes: palmaris brevis; muscle that abducts the little finger; flexor little finger brevis and oppons little finger muscle. They arise from the nearby carpal bones and attach to the base of the proximal phalanx of the fifth finger and the fifth metacarpal bone. Their function is determined by the name of the muscles themselves.

Fingers

Fingers are a unique tool given to us by evolution, allowing us to perform the most complex operations that are inaccessible to any other living creature on earth, helping to communicate and express our emotions.

Try not using your hands for a while. Difficult? Not difficult, but almost impossible! The main function of the hands, especially small, subtle movements, is provided by the fingers. The absence of such a small organ compared to the size of the entire body even imposes restrictions on the performance of certain types of work. Thus, the absence of a thumb or part of it may be a contraindication to driving.

Description

Our limbs end with fingers. A person normally has 5 fingers on his hand: a separate thumb, opposed to the rest, and the index, middle, ring and little fingers arranged in a row.

Man received this separate arrangement of the thumb during evolution. Scientists believe that it was the opposable finger and the associated well-developed grasping reflex that led to a global evolutionary leap. In humans, the thumb is located in this way only on the hands (unlike primates). In addition, only a human can connect the thumb with the ring and little fingers and has the ability to both have a strong grip and small movements.

Functions

Thanks to the variety of movements in which the fingers are involved, we can:

grasp and hold objects of varying sizes, shapes and weights;
perform small precise manipulations;
write;
gesticulate (the lack of ability to speak led to the intensive development of sign language).

The skin of the fingertips has folds and stripes that form a unique pattern. This ability is actively used to identify a person by law enforcement agencies or the security system of employers.

Structure

The basis of the fingers is the bony skeleton. The fingers consist of phalanges: the smallest, nail or distal, middle phalanx and proximal phalanx (have all fingers except the thumb). The phalanges of the fingers are small tubular bones - hollow inside. Each phalanx has a head and a base. The middle thinnest part of the bone is called the body of the phalanx. The nail phalanx is the smallest and ends at the distal phalangeal tubercle.
The connection of the head and base of adjacent phalangeal bones forms the interphalangeal joints - distal (located further from the body) and proximal (located closer to the body). The thumb has one interphalangeal joint. The interphalangeal joints are typical axial joints. Movements in them occur in the same plane - flexion and extension.
The finger joints are secured by palmar and collateral ligaments, running from the heads of the phalangeal bones to the base of other bones or to the palmar surface of an adjacent bone.
The muscular system of the fingers is just part of the muscles of the hand. The fingers themselves have practically no muscles. The tendons of the hand muscles, which are responsible for the mobility of the fingers, are attached to the phalanges of the fingers. The lateral group of muscles of the palmar surface of the hand provides movements of the thumb - its flexion, abduction, adduction, opposition. The medial group is responsible for the movements of the little finger. Movements of 2–4 fingers are ensured by contraction of the muscles of the middle group. The flexor tendons attach to the proximal phalanges of the fingers. Extension of the fingers is ensured by the finger extensor muscles located on the back of the hand. Their long tendons are attached to the distal and middle phalanges of the fingers.
The tendons of the hand muscles are located in peculiar synovial sheaths that extend from the hand to the fingers and reach the distal phalanges.
The fingers are supplied with blood from the radial and ulnar arteries, which form arterial arches and multiple anastomoses on the hand. The arteries that supply the tissues of the finger are located along the lateral surfaces of the phalanges, along with the nerves. The venous network of the hand originates from the fingertips.
The space between the internal structures of the finger is filled with fatty tissue. The outside of the fingers, like most of our body, is covered with skin. On the dorsal surface of the distal phalanges of the fingers in the nail bed there is a nail.

Finger injuries

When performing various types of work, injury to the fingers is the most common. This is due to the fact that it is with the help of our fingers that we do the bulk of the work. Conventionally, finger injuries can be divided into several groups:

soft tissue injury - cut, bruise, compression,
injury to a bone or joint - fracture, dislocation, sprain,
thermal injuries - frostbite, burns,
traumatic amputations,
damage to nerves and tendons.

Symptoms depend on the type of injury, but all injuries are characterized by common signs - pain of varying intensity, tissue swelling, hemorrhage or bleeding in open injury, impaired movement of the injured finger.

Little finger

The smallest, medially located finger. Carry the most minimal functional load. The meaning of the word little finger in Russian is younger brother, younger son.

Ring finger

Located between the little finger and middle finger - it is practically not used independently, which is explained by the commonality of the tendons of adjacent fingers. Bears independent load when playing keyboard instruments or typing. There was a belief that from this finger a vein went straight to the heart, which explains the tradition of wearing wedding rings on this finger.

Middle finger

Its name speaks for itself - it is located in the middle of the finger row. The longest finger of the hand is more mobile than the ring finger. In sign language, the middle finger is used to make an offensive gesture.

Forefinger

One of the most functional fingers on the hand. This finger is able to move independently of the others. This is the finger we point most often.

Thumb

The thickest, free-standing finger. It has only 2 phalanges, opposed to the rest, which ensures perfect grasping ability of the hand. The thumb is actively used in gesture communication. The width of the thumb was formerly used as a measurement unit equal to 1 centimeter, and the inch was originally defined as the length of the nail phalanx of the thumb.

Question answer

What should be the first aid for a broken finger?

A fracture of a finger can be suspected if, immediately after the injury, severe pain appears, swelling of the finger, its unnatural position, impaired movement, and crunching of bone fragments when palpated.

First aid equipment:

ensure the immobility of the injured finger using splints made from available materials - you can fix the finger with a ruler placed on the palmar surface of the finger, extending over the hand and wrist to prevent their movements;
relieve pain - any painkillers will do;
apply cold to the injury site;
in case of damage to the skin, it is necessary to apply a sterile bandage;
in case of intense bleeding when the blood vessels of the finger are damaged by bone fragments, it is necessary to apply a tourniquet to the base of the finger or to the wrist. For moderate bleeding, a thick bandage is sufficient;
consult a doctor immediately.

How to get rid of calluses on your fingers from a pen?

People who write a lot by hand during the day develop an unsightly callus on the nail phalanx of the middle finger. You can reduce it by carrying out regular procedures aimed at softening and exfoliating dead skin - using scrubs and moisturizing creams. To prevent the occurrence of this problem, you can use special silicone loops that fit on your finger when writing and prevent the skin from becoming rough and thick.

Components of the hand

Without arms, hands, palms, fingers, it would be very difficult for a person. The wrist joint is responsible for the functionality of the hands. You need to take care of your hands no less than your eyes. They are a unique tool created by nature itself, which you cannot do without.

It is the hand that a person puts forward when falling. She is the first to suffer from various fractures and injuries. What do you need to know about the structure of your hands in order to be able to preserve them?

Structure of the human hand

The anatomy of the human hand is considered one of the most complex. It is impossible to imagine limbs without arteries, veins, nerves and muscles. The bone tissue of the arm and hand is distinguished by its specific density and structure. The ligaments and tendons in the upper and lower extremities form a whole network. Sensory information enters the brain through the hands. He gives signals, and the hand begins to manipulate objects. One has only to give the brain a command, and the tendons and ligaments of the hand are instantly distracted by it.

The contraction of tendons and ligaments in the human body occurs constantly. The more movements the hand makes, the stronger their contraction will be. If the hands are inactive, this fact is directly reflected in their condition. The load on the arms occurs constantly, the lion's share of it falls on the muscles.

The top of the hand is covered with skin. It is this that protects the hand and the entire arm from the aggressive influence of the external environment, which can affect the quality of its functioning. You need to know: the skin tissue of the hand, like any other part of the body, maintains a stable body temperature.

The skin of the hand protects the hands from bacteria entering their interior. Toxic substances can cause harm to the human body. The skin is a natural barrier against various negative components.

Substances that protect the skin of the hands from external influences

The layer of skin on the hand is uneven. Pay attention to the condition of your hands on a frosty day: the back of the limb freezes more than the inside. The palm always dries out faster than the back if moisture gets on the organ. This is due to the fact that the number of sweat and sebaceous glands here is less than in the upper part of the arm. The arm contains blood and lymphatic vessels and nerves.

What substances make the skin of the hand elastic, preventing it from bursting from constant stress? These substances are:

These substances belong to the category of proteins. But they are quite vulnerable to ultraviolet radiation, which can penetrate the top layer of skin. If a person’s hands become unaesthetic, wrinkled, and lose elasticity, then all this is a consequence of exposure to ultraviolet radiation, which destroys proteins. This mechanism does not start instantly.

Melanin is formed in the skin of the hand, as in any other part of the skin of the body. The fact that human skin is able to absorb the effects of ultraviolet rays is his merit. However, if the human body is exposed to prolonged exposure to ultraviolet rays, age spots begin to form on the hand.

Bones that form the hand

The anatomy of the human hand has been the subject of medical study for thousands of years. Hippocrates wrote about what elements the limbs are made of and what the carpal joint is, whose discoveries have not lost their value even today. Renaissance artists played an equally significant role in studying the structure of the hand. Outstanding figures of the Enlightenment era gave a completely reliable idea of it in their works.

Largest bones and joints of the hand

Today, the hand is a subject of consideration not only in medicine. It is studied by representatives of scientific fields related to robotics and nanotechnology. It was the hand that became the prototype of modern manipulators, a source of ideas for a number of engineering technologies aimed at maximum automation of production operations.

If you count the bones of your fingers and wrist, you get the number 27. What holds the bones of the hand and muscles together? Tendons, the dysfunction of which is no less dangerous than joints. 8 bones are the basis of the skeleton of the hand. They are not isolated, autonomously operating structures - they are located in a group. It is these 8 bones of the hand that form the part of the body that is commonly called the wrist. The bones located at the wrist look very unusual: they form two rows. The first consists of the scaphoid or lunate bone. There are two more types of bones located at the wrist: triquetral and pisiform. The second row of bones located in the carpal bones is the trapezium, capitate and hamate bones. The arm bone is usually divided into 3 parts: its base, head and body.

Next is the metacarpus of the hand. Sometimes it is called "finger bones", but this is incorrect. After the metacarpal bones, only the bones of the fingers are located, and they are already a completely different part of the limb. There are 14 such bones, they form the phalanges of the fingers. The fingers, from the index to the little finger, have 3 phalanges. The exception is the thumb: the bones of the thumbs consist of two phalanges.

Muscles, blood vessels and relationships between parts of the hand

Structure of the hand: muscles and tendons

Muscles play a special role in the functioning of the hand. They are located carpal and below. Movement of the fingers of the hand, like the hand itself, is impossible without the participation of muscles that perform different roles. The muscles that affect the condition of the hand and wrist are anterior, posterior or internal. Anterior and posterior carpals are placed. The former are responsible for bending the hand, without the latter it is impossible to extend it. Its internal muscles carry out the movements of the fingers. Brushes perform a number of vital functions for humans. They provide clear coordinated hand movements.

There is a misconception: most of the human sensory cells are located at the wrist. No, this category of cells is located in another area of the hand - at the tips of the fingers. It is she who makes it possible to experience the world through touch. The carpal tissues do not have the same sensitivity as the fingertips. Nails protect such a vulnerable part of the hand. The nail is a horny plate, the basis of which is keratin. If the amount of keratin in the nails decreases, this increases the vulnerability of the lower part of the hand to pain. This substance is also found in the skin, but in the nail it has different properties. The more keratin in the nails, the stronger they are.

The blood supply to the joints comes from the deep palmar arterial arch, palmar and dorsal arterial network. Its quality directly affects not only the joint tissue, but also the condition of the hand. Good blood supply to the hand allows it to function actively.

All parts of the hand are closely interconnected with each other: disruption of tissue functioning in one area will immediately affect another.

Joints of the hand

The hand has joints, which are usually classified according to their location. The joint is no less important part in the functioning of the hand than ligaments, muscles, skin, and bones. The wrist joint is considered the most complex in its structure. It resembles an ellipse, which is strengthened by various types of ligaments.

Internal structure of fingers

This joint is involved in flexion and extension. This wrist joint has one feature: it is able to combine different types of movements. The midcarpal joint is the junction of the proximal and distal rows of bones. It is attached by ligaments of the hand and has a separate articular capsule. The intercarpal joints in this area form a separate group of tissues. Each such joint connects the bones of the wrist. This ensures the normal functioning of the hand, which involves various movements: grasping, throwing, etc.

The pisiform joint is located in a tendon. Together with the triangular bone of the hand, it forms a single whole. The thumb has another joint, which is saddle-shaped. This is the carpometacarpal joint. It is capable of moving around two axes and is responsible for grasping movements: through it, people can control their hand when grasping an object. It is believed that this particular carpometacarpal joint is the main feature of the human hand, distinguishing it from the paws of mammals. It will not be difficult to find such a wrist joint on the hand. It is flat in shape. It is located between the second row of carpal bones and the 2nd-4th row of metacarpal bones.

The intermetacarpal joint belongs to another group of articular tissues. Between the bases of the 2-5 metacarpal bones there is such a joint. The metacarpophalangeal joint will differ significantly in its functioning and location. If the joint is located on the 2-5th finger of the hand, its shape will be spherical. It is in this area, where the interphalangeal joints of the hand are located, that the tendons and median nerve are located. This is another separate group. The related carpal joint is located between the head and base of the middle phalanx. It is located between the middle head and the base of the terminal phalanges. Such a wrist joint can lose its shape and become deformed during operation.

People's hands are often injured. To strengthen bones, ligaments and joints, doctors recommend drugs that promote tissue restoration and renewal, as well as health-improving physical exercises.

Wrist

One of the most functional elements of the human body is the hand. It is this adaptation that exalts Homo sapiens over many mammals. It is quite difficult to imagine a full life without healthy arms and hands. Even the simplest daily movements of the hands (brushing teeth, fastening buttons, combing) will be impossible if the upper limb is damaged. The structure of the hand has a number of features, let’s try to understand the main ones.

Structural features of the human hand

The human hand has a specific and complex structure. The anatomy of the hand is a complex complex mechanism consisting of various elements:

The bone frame (carpal skeleton) provides the hardness and strength of the entire limb.
Tendons and ligaments connect the bone base and muscles, provide elasticity and flexibility of the limb, and also participate in the formation of joints.
The vessels provide nutrition to the tissues of the hand and provide them with oxygen.
Nerve fibers are responsible for the sensitivity of the skin of the limb, contraction and relaxation of muscles, and provide a reflex response to an external stimulus.
The skin performs a protective function, delimiting the structures of the hand from environmental factors and regulating internal temperature.

Each component part of the human hand performs its own functions, but together they provide various manipulations of the hand, from the most simple to the complex. The presented figure shows the main elements of the upper limb.

Elements of the hand

Leather properties

The skin covers the entire body, in some places it is softer, in others it is rougher. What determines the nature of the skin? Everyone knows that the palm has thicker skin than the back surface. This is due to the fact that it is the palmar surface of the hand that is most often exposed to friction, chemical and mechanical stress. Thus, the skin protects muscles, blood vessels and nerve fibers from environmental influences.

The dorsal surface has a larger number of sebaceous and sweat glands than the palmar surface. The elasticity of the skin of the hands and its firmness depend on the amount of collagen and elastin in it, which are specific proteins. These substances are destroyed by ultraviolet radiation. With a decrease in the content of collagen and elastic fibers in the thickness of the skin of the hands, dryness, wrinkles, and cracking are observed. These signs are more common in older women, but there are exceptions. One of the earliest symptoms of excessive exposure to ultraviolet radiation on the skin is the appearance of age spots.

Bone apparatus

How many bones are there in a person's hand? Each of us has asked ourselves this question at least once. The hand consists of 27 small bones. So, the human hand consists of several sections:

The wrist is a structure consisting of 8 grouped bones connected by ligaments. The wrist includes such bones as: scaphoid, trapezium, pisiform, triquetrum, trapezoid, hamate, capitate, lunate.
Metacarpus - is a row consisting of five oblong bones. This section of the hand is located between the wrist and fingers.
Fingers of the hand - four fingers of 3 phalanges and a thumb of two phalanges.

The bones of the hand are quite small, but it is their small size that increases the flexibility and stability of the hand frame during physical impact on the skeleton. The bones of the hand are most often subject to significant stress. After all, each of us has noticed at least once in our lives that when we fall, our upper limbs reflexively move forward. The structure of a human limb can be seen in the photo below.

Muscular apparatus

Undoubtedly, movements of the hand would be impossible without the participation of muscles. The skeletal muscles of the hand and fingers ensure clarity and coordination of movements in them. The muscular system of the arm consists of many individual muscles located in layers on both sides. Some of them are responsible for bending the palm, others for extending it. The muscles of the hand are attached to the bones by tendons and ligaments. Damage to any of the listed components of the hand makes it impossible to perform its basic functions. The muscles of the hand turn into tendons, which are attached to the bone base. Thus, due to the coordinated work of the nervous, vascular and ligamentous-muscular systems, the entire skeleton moves.

Muscular apparatus of the right hand

Joints and ligamentous apparatus

The most complex and important wrist joint is the wrist. The wrist joint is formed by the ulna, the radiocarpal bone of the elbow, and the wrist. The bones of the elbow form a complex elliptical joint with the wrist. Its importance is quite great, since it is one of the few joints that provide combined movements of the arm (rotation, flexion and extension). The wrist joint is considered the key joint of the upper limb. However, the role of all other joints of the hand should not be underestimated, since only together they form a complete skeleton of the hand. The coordinated work of the wrist and other joints ensures its normal and full functioning. Thanks to normal mobility in the joints, the muscles of the hand can fully contract and relax, moving the skeleton. The following figure gives an idea of how the wrist and other joints of the upper limb are located.

Joints and ligamentous apparatus

Innervation or nervous system

Many people are mistaken in believing that the back of the hand is most supplied with nerve endings. In fact, most of them are at the fingertips. It is the abundance of nerve endings on the fingertips that provides tactile and sensory sensitivity. In people with visual impairments (especially congenital ones), the ability to perceive the world through touch with their fingertips is especially developed. Nails protect such sensitive areas. Nail plates are formed from keratin. If the amount of keratin in nails decreases, they become brittle and thin.

Blood supply to the hands

Nutrition for all structures of the human hand is provided by the radial and ulnar arteries, forming deep and superficial arcs of blood supply. The abundance of vessels and a complex network of anastomoses ensure the most efficient functioning of the limb.

Blood supply to the hand

How is a human hand different from a monkey's?

We all remember from the school curriculum one of the most famous theories of the origin of humans from primates. Indeed, the human body (including the skeleton) has certain similarities with the body of primates. The same applies to the structure of the hand. However, if this hypothesis is consistent, the human hand has undergone significant transformation during the process of evolution. Labor is considered the evolutionary “engine” of such development. Thus, the human upper limb has a number of structural features:

saddle shape of the 1st carpometacarpal joint;
the groove for the tendons of the hand, nerve fibers and blood vessels in the wrist area has deepened;
the bones of the 1st finger have become wider in comparison with the others;
the length of the phalanges from the 2nd to 5th fingers is shorter than that of the monkey;
The palmar bones of the hand, which are connected to the 1st finger, have shifted towards the palm.

The structure of the human hand has a number of features that ensure precise and coordinated movements.

, lunate, triangular, pisiform;

lower: trapezium bone, trapezoid, capitate, hamate.

The next row of hand bones form the metacarpal bones. There are five bones, according to the number of fingers. Their bases are connected by the carpal bones. The phalanges of the fingers, like the metacarpal bones, are short tubular bones. Each finger has three phalanges: main (proximal), middle and terminal or nail (distal). The exception is the thumb, which is formed by only two phalanges - the main and the nail. Movable joints are formed between the metacarpal bone and the phalanges of each finger.

The hand has three sections: wrist, metacarpus and fingers.

Carpal bones

The proximal row consists of the following bones, if you go from the thumb to the fifth finger: scaphoid, lunate, triquetrum and pisiform.

The distal row also consists of four bones: polygonal, trapezoid, capitate and hamate, which with its hook faces the palmar side of the hand.

On the Rook (scaphoid bone) under the Moon (lunate bone) Three (triquetral bone) ate Peas (pisiform bone), And they took fish heads (capitate bone) from the Hook (hoove bone), And then they folded the Trapezoid (trapezoid bone) Trapezoid (trapezoid) ).

The proximal row of carpal bones forms an articular surface convex towards the radius. The distal row is connected to the proximal row using an irregularly shaped joint.

The bones of the wrist lie in different planes and form a groove (carpal groove) on the palmar surface and a bulge on the back. The groove of the wrist contains the tendons of the finger flexor muscles. Its inner edge is limited by the pisiform bone and the hook of the hamate, which are easily palpable; the outer edge is composed of two bones - the scaphoid and the trapezium.

Metacarpal bones

Finger bones

Each finger consists of three phalanges: proximal, middle and distal. The exception is the first finger, which has only two phalanges - proximal and distal. The proximal phalanges are the longest, the distal phalanges the shortest. Each phalanx has a middle part - a body and two ends - proximal and distal. At the proximal end is the base of the phalanx, and at the distal end is the head of the phalanx. At each end of the phalanx there are articular surfaces for articulation with adjacent bones.

Sesamoid bones of the hand

Joints of the hand

Wrist joint

In the radiocarpal joint, which has an ellipsoidal (ovoid) shape, flexion and extension, adduction and abduction of the hand are possible. Pronation and supination of the hand occur together with the same movements of the bones of the forearm. A small passive rotational movement is also possible in the radiocarpal joint (10-12°), but this occurs due to the elasticity of the articular cartilage. The position of the gap of the radiocarpal joint is determined from the dorsal surface, where it is easily detected through the soft tissues; in addition, its position is determined from the radial and ulnar sides. On the radial side, in the area of the inferior radial fossa, you can palpate the gap between the lateral styloid process and the scaphoid bone. On the ulnar side, a depression is felt between the head of the ulna and the triquetral bone, corresponding to the ulnar portion of the cavity of the radiocarpal joint.

Movements in the radiocarpal joint are closely related to movements in the midcarpal joint, which is located between the proximal and distal rows of carpal bones. This joint has a complex, irregularly shaped surface. The total range of mobility when flexing the hand reaches 85°, and when extending it is also approximately 85°. Adduction of the hand in these joints is possible by 40°, and abduction by 20°. In addition, circular movement (circumduction) is possible in the radiocarpal joint.

The radiocarpal and midcarpal joints are strengthened by numerous ligaments. The ligamentous apparatus of the hand is very complex. The ligaments are located on the palmar, dorsal, medial and lateral surfaces of the wrist, as well as between the individual bones of the wrist. The most important are the collateral ligaments of the wrist - the radial and ulnar. The first goes from the lateral styloid process to the scaphoid bone, the second - from the medial styloid process to the triquetral bone.

Between the bony elevations on the radial and ulnar sides of the palmar surface of the hand there is a ligament - the flexor retinaculum. It is not directly related to the joints of the hand, but is, in fact, a thickening of the fascia. Throwing over the carpal groove, it turns it into the carpal tunnel, where the flexor tendons of the fingers and the median nerve pass.

Carpometacarpal joints of the hand

The carpometacarpal joint of the thumb is formed by the polygonal bone and the base of the first metacarpal bone. The articular surfaces are saddle-shaped. The following movements are possible in the joint: adduction and abduction, opposition (opposition) and reverse movement (reposition), as well as circular movement (circumduction). Thanks to the opposition of the thumb to all other fingers, the volume of grasping movements of the hand increases significantly. The amount of mobility in the carpometacarpal joint of the thumb is 45-60° during abduction and adduction and 35-40° during opposition and reverse movement.

Metacarpophalangeal joints of the hand

Interphalangeal joints of the hand

Fibrous and synovial sheaths of the tendons of the fingers

The ligaments, the flexor retinaculum and the extensor retinaculum are of great importance for strengthening the position of the muscle tendons passing under them, especially when flexing and extending the hand: the tendons rest on the named ligaments from their inner surface, and the ligaments prevent the tendons from moving away from the bones and with strong muscle contraction withstand significant pressure.

The sliding of the tendons of the muscles passing from the forearm to the hand and the reduction of friction are facilitated by special tendon sheaths, which are fibrous or osteo-fibrous canals, inside of which there are synovial sheaths, which in some places extend beyond these canals. The largest number of synovial sheaths (6-7) is located under the extensor retinaculum. The formation of the canals involves the ulna and radius bones, which have grooves corresponding to the passage of the muscle tendons, and fibrous bridges that separate one canal from the other, which go from the extensor retinaculum to the bones.

Muscles of the hand

The musculature of the hand is a complex complex of approximately 33 muscles. Most of them are located in the forearm and are connected by tendons to the phalanges of the fingers through several joints. Two groups of muscles form two elevations on the palmar surface of the hand: thenar (thenar) - the elevation of the thumb and the hypothenar (hypothenar) - the elevation of the little finger. On the hand, the muscles are located only on the palmar side. Here they form three groups: the middle one (in the middle section of the palmar surface), the thumb muscle group and the small finger muscle group. The large number of short muscles on the hand is due to the fine differentiation of finger movements.

Middle hand muscle group

Comprises:

vermiform muscles, which originate from the tendons of the deep flexor digitorum and are attached to the base of the proximal phalanges of the second to fifth fingers;

The human hand has a specific and complex structure. The anatomy of the hand is a complex complex mechanism consisting of various elements:

The bone frame (carpal skeleton) provides the hardness and strength of the entire limb.
Tendons and ligaments connect the bone base and muscles, provide elasticity and flexibility of the limb, and also participate in the formation of joints.
The vessels provide nutrition to the tissues of the hand and provide them with oxygen.
Nerve fibers are responsible for the sensitivity of the skin of the limb, contraction and relaxation of muscles, and provide a reflex response to an external stimulus.
The skin performs a protective function, delimiting the structures of the hand from environmental factors and regulating internal temperature.

Leather properties

How many bones are there in a person's hand? Each of us has asked ourselves this question at least once. The hand consists of 27 small bones. So, the human hand consists of several sections:

The wrist is a structure consisting of 8 grouped bones connected by ligaments. The wrist includes such bones as: scaphoid, trapezium, pisiform, triquetrum, trapezoid, hamate, capitate, lunate.
Metacarpus - is a row consisting of five oblong bones. This section of the hand is located between the wrist and fingers.
Fingers of the hand - four fingers of 3 phalanges and a thumb of two phalanges.

Muscular apparatus

Innervation or nervous system

Blood supply to the hands

How is a human hand different from a monkey's?

saddle shape of the 1st carpometacarpal joint;
the groove for the tendons of the hand, nerve fibers and blood vessels in the wrist area has deepened;
the bones of the 1st finger have become wider in comparison with the others;
the length of the phalanges from the 2nd to 5th fingers is shorter than that of the monkey;
The palmar bones of the hand, which are connected to the 1st finger, have shifted towards the palm.

The structure of the human hand has a number of features that ensure precise and coordinated movements.

The arm is the upper limb of the human body; it consists of 30 bones, 43 joints and many muscles. The anatomical structure of the human hand is unique: a person has a special ability to grasp objects and consciously perform work with them. This distinguishes humans from animals and other life forms on our planet.

Human hands perform many different movements. The arms are not as strong as the lower limbs, but they are capable of a variety of manipulations, with the help of which we can explore and understand the world around us. The upper limb consists of four segments:

shoulder girdle,
shoulder,
forearms,
brushes

The skeleton of the shoulder girdle is formed by the collarbone and shoulder blades, to which the muscles and upper part of the sternum are attached. Through the joint, one end of the clavicle is connected to the upper part of the sternum, the other to the scapula. On the scapula there is a glenoid cavity - a pear-shaped depression into which the head of the humerus enters. The shoulders can be lowered, raised, moved back and forth, i.e. The shoulders provide maximum range of motion of the upper limbs.

The arm is attached to the body through the bones of the shoulder girdle, joints and muscles. Consists of 3 parts: shoulder, forearm and hand. The shoulder girdle is the most powerful. Bending your arms at the elbow gives your arms greater mobility, increasing their amplitude and functionality. The hand consists of many movable joints, it is thanks to them that a person can click on the keyboard of a computer or mobile phone, point a finger in the desired direction, carry a bag, draw, etc.

How many bones are there in a hand?

The shoulder girdle consists of two bones - the collarbone and the scapula, and the arm itself consists of 30 bones. Let's list them by department from top to bottom:

Shoulder – humerus bone.
Forearm – ulna and radius bones.
Hand – 27 bones (wrist – 8, metacarpus – 5, fingers – 14).

The shoulders and hands are connected through the humerus, ulna and radius. All three bones are connected to each other using joints. At the elbow joint, the arm can be bent and extended. Both bones of the forearm are connected movably, so during movement in the joints, the radius rotates around the ulna. The brush can be rotated 180 degrees!

Structure of the hand

The wrist joint connects the hand to the forearm. The hand consists of the palm and five protruding parts - the fingers. It includes 27 small bones. The wrist consists of 8 small bones - the scaphoid, lunate, triquetrum, pisiform, trapezoid, trapezoid, capitate and hamate. All of them are connected to each other by strong ligaments.

The bones of the wrist, articulating with the bones of the metacarpus, form the palm of the hand. There are 5 metacarpal bones attached to the carpal bones. The first metacarpal bone is the shortest and flattest. It connects to the bones of the wrist through a joint, so a person can freely move the thumb and move it away from the rest. The thumb consists of two phalanges, the remaining fingers - of three.

Upper limb joints

Hand joints are usually divided into 2 groups - large and small. The group of large joints includes 3 joints located above the wrist:

The shoulder girdle is a spherical head that can rotate in different directions, making movements of the shoulder girdle smooth and painless.
Elbow - responsible for flexion and extension of the arm.
Radiocarpal - connects the radius to the wrist, is very mobile, provides many functions. Through this joint, the movable hand is attached to the forearm.

The group of small joints includes the joints of the hand - there are many of them, but they are small. They connect the bones of the wrist, five and fingers into a single system, characterized by enormous mobility, the ability to grasp objects and indicate direction. The greatest range of movements is performed by the metacarpophalangeal joints, which attach the finger phalanges to the stationary part of the hand.

Ligaments and muscles of the hand

In the structure of the arm, an important place is occupied by muscles that allow the upper limb to perform various movements and withstand loads. The muscles provide smooth and precise movements, as well as fine motor skills, which greatly enhance the functionality of the human hand.

Ligaments and tendons provide support for all parts of the skeleton. They are made of connective tissue and set the limits of joint mobility, making them work more smoothly and reliably.

The muscles of the arm are represented by the muscles of the shoulder, forearm and hand. Most of the muscles that move the hands and fingers are located in the forearm. With the participation of muscles, the tendons located near the bones of the wrist perform a flexion-extension function. Tendons are held firmly together by ligaments and connective tissue. The muscle tendons pass through the canals. The walls of the canals are lined with a synovial membrane, which ends at the tendons and forms their synovial sheaths. The fluid in the vagina acts as a lubricant and ensures free sliding of the tendons.

Shoulder joint ligaments:

Acromioclavicular.
Coracoclavicular.
Coracoacromial.
Upper, middle and lower glenohumeral ligaments.

Muscles of the shoulder girdle:

Deltoid.
Supraspinatus.
Infraspinatus.
Small round.
Big round.
Subscapular.

Shoulder muscles:

Anterior - coracobrachialis, biceps, brachialis.
Rear – triceps (triceps), ulna.

The biceps is connected to the forearm by ligaments and tendons. The upper part of the muscle is divided into two heads, which are attached to the scapula by tendons. At the site of their attachment there is a synovial bursa. The main function of the biceps is to bend and raise the arm, so in people who do heavy physical work or are actively involved in sports, these muscles are very well developed.

The triceps brachii muscle consists of a lateral, medial and long head. The bundles of all three parts of the muscle are connected into one whole and pass into the tendon. At the junction of the tendon there is a synovial bursa. The triceps muscle, located at the back of the shoulder, and the deltoid muscle, located above the shoulder joint, are attached to the shoulder blade. The levator muscle supports the scapula. Other muscles of the shoulder girdle are located in the chest and neck area.

Ligaments of the forearm:

Front.
Rear.
Radial.
Elbow.

Forearm muscles:

Brachioradial.
Aponeurosis of the biceps brachii muscle.
Large pronator.
Flexor carpi radialis.
Long palm.
Flexor carpi ulnaris.
Superficial flexor digitorum.

Hand ligaments:

Intercarpal.
Dorsal and palmar wrists.
Ulnar and radial.

Muscles of the hand:

Lateral group (muscles of the thumb).
Medial group (musculature of the little finger).
Middle group.

The blood supply to the upper limb is carried out by the subclavian artery, which originates at the level of the first rib, then passes into the axillary and brachial artery. Then the size of the blood vessels becomes smaller and smaller, and the hand is covered with many small capillaries.

Thus, the anatomical structure of the hand allows it to perform a range of movements and grips, including under load. The amazing combination of bones, muscles and ligaments of the hand into one system makes the upper limb adapted to perform various useful functions and tasks, which helps a person more easily adapt to the world around him.

Video on the topic (bones of the upper limb):