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What does a human hand consist of? The structure of the human hand with names

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 in it: the bones of the hand; ligaments of the hand that hold bones and form joints; hand muscles.

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

wrist bones The eight small carpal bones are irregularly shaped. They are located in two rows.

The proximal row is made up of the following bones, if you go from the side of the thumb to the side of the fifth finger: scaphoid, lunate, trihedral and pisiform.
The distal row is also made up of four bones: polygonal, trapezoid, capitate and hook-shaped, which with its hook faces the palmar side of the hand.
The proximal row of carpal bones forms an articular surface convex towards the radius. The distal row is connected to the proximal row with 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 tendons of the flexor muscles of the fingers run in the groove of the wrist. Its inner edge is limited by the pisiform bone and 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 differs in its massiveness. The longest is the second metacarpal bone. The following bones decrease in length towards the ulnar edge of the hand. Each metacarpal has a base, body, and head.
The bases of the metacarpal bones articulate with the carpal bones. 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 phalanges 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 inconstant 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 occasionally they are also found on the dorsal surface. The pisiform bone is also referred to as a sesamoid bone. All sesamoid bones, as well as all bone processes, increase the leverage of the muscles that attach to them.

Ligament apparatus of the hand

wrist joint
The radius and bones of the proximal row of the wrist take part in the formation of this joint: the scaphoid, lunate and trihedral. The ulna does not reach the surface of the radiocarpal joint (it is “complemented” by the articular disc). Thus, in the formation of the elbow joint, the ulna plays the largest role of the two bones of the forearm, and in the formation of the radiocarpal joint, the radius.
In the radiocarpal joint, which has an elliptical shape, flexion and extension, adduction and abduction of the hand are possible. Pronation and supination of the hand occurs along with the same movements of the bones of the forearm. A small passive movement of a rotational nature is also possible in the radiocarpal joint (by 10-12 °), however, it occurs due to the elasticity of the articular cartilage. The position of the fissure of the radiocarpal joint is determined from the back surface, where it is easily detected through soft tissues; in addition, its position is determined from the radial and ulnar sides. On the radial side, in the region of the inferior radial fossa, one can feel the gap between the lateral styloid process and the navicular bone. On the ulnar side, a recess is palpated 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 surface of irregular shape. The total amount of mobility during flexion of the hand reaches 85°, and during extension it is also approximately 85°. Adduction of the hand in these joints is possible by 40°, and abduction by 20°. In addition, a circular motion (circumduction) is possible in the radiocarpal joint.
The radiocarpal and midcarpal joints are reinforced with numerous ligaments. The ligamentous apparatus of the hand is very complex. 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 radius and the ulna. The first goes from the lateral styloid process to the navicular bone, the second - from the medial styloid process - the trihedral bone.
Between the bone elevations on the radial and ulnar sides of the palmar surface of the hand, a ligament is thrown - the flexor retainer. It is not directly related to the joints of the hand, but is, in fact, a thickening of the fascia. Throwing over the groove of the wrist, it turns it into a carpal tunnel, where the tendons of the flexors of the fingers and the median nerve pass.


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 motion 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 bones of the wrist to each other, as well as to the metacarpal bones. On the hand, ligaments can be distinguished that run arcuately, radially and transversely. The central bone of the ligamentous apparatus is the capitate, to which a greater number of 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 the thickening of the capsules that cover the joints between these bones. The second row of carpal bones, in addition to the palmar and dorsal ligaments, 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 nucleus of the hand, they are designated as a solid base 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). Due 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° in abduction and adduction and 35-40° in opposition and reverse movement.

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 motion (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. Their fibers are intertwined with the fibers of the deep transverse metacarpal ligament, which prevents the heads of the metacarpal bones from moving apart.

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

Fibrous and synovial sheaths of the tendons of the fingers

The ligaments of the flexor retinaculum and the extensor retinaculum are of great importance for strengthening the position of the muscle tendons passing under them, especially during flexion and extension of 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 bone-fibrous channels, inside of which there are synovial sheaths, in some places extending beyond these channels. The largest number of synovial sheaths (6-7) is located under the extensor retinaculum. The formation of channels involves the ulna and radius bones, which have grooves corresponding to the places where the tendons of the muscles pass, and fibrous bridges that separate one channel from another, which go from the extensor retinaculum to the bones.
The palmar synovial sheaths belong to the tendons of the flexors of the hand and fingers that run in the carpal tunnel. The tendons of the superficial and deep flexors of the 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 long flexor of the thumb is in a separate synovial sheath, which passes along with the tendon to the finger. In the area of ​​the palm, the tendons of the muscles that go to the second, third and fourth fingers are deprived of synovial sheaths at 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: middle (in the middle section of the palmar surface), a group of muscles of the thumb and a group of muscles of the thumb. A large number of short muscles on the hand is due to the fine differentiation of finger movements.

Middle group of muscles of the hand
Consists of worm-like muscles that start from the tendons of the deep flexor of the fingers 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 the flexion of the proximal phalanges of these fingers. In addition, the palmar interosseous muscles bring the fingers of the hand to the middle finger, and the dorsal interosseous muscles spread them apart.

thumb muscle group
Forms the so-called elevation of the thumb on the hand. They start on the nearby bones of the wrist and metacarpus. Among them, there are: a short muscle that removes the thumb, which is attached to its proximal phalanx; a short flexor of the thumb, attached to the external sesamoid bone, located at the base of the proximal phalanx of the thumb; muscle that opposes the thumb, going to the first metacarpal bone; and the adductor thumb muscle, which inserts on 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: a short palmar muscle; muscle that removes the little finger; the short flexor of the little finger and the muscle that opposes the little finger. They originate from nearby carpal bones and insert at the base of the proximal phalanx of the fifth toe and fifth metacarpal. Their function is determined by the name of the muscles themselves.

Materials used in the article: sportmedicine.ru

One of the most functional parts of the human body is the hand. This mechanism distinguishes humans from other mammals. A brush is a really important element, because in everyday life a person needs to constantly hold objects and perform elementary movements. But all this is impossible if such a device is badly damaged. The hand contains some features in its structure that need to be studied.

The structure of the human hand

The human hand has a very complex and highly non-trivial structure.

It consists of the following parts:

  • which gives strength to the limb.
  • Muscles with bones connecting tendons. They make the brush flexible and quite elastic.
  • Tissues of the human hand, feeding with the help of the vessels located in them.
  • Nerves, which are responsible for the response reflex reaction to the action of the environment. They increase sensitivity and contract the muscle of the hand.
  • Leather It has the property of protection, but it also draws boundaries between the human body and the external environment, maintains the temperature in the body.

The human hand includes in its structure 27 small bones.

Brush departments:

  1. Fingers. The brush includes 4 fingers, which consist of 3 phalanges, there is also a large one, consisting of two phalanges.
  2. metacarpus. This is the part of the hand that is located between the fingers and the wrist. It consists of five small bones, oblong in shape.
  3. Wrist. This is a system that consists of 8 bones connected by ligaments.
  • Trapeze.
  • Scaphoid.
  • Hook-shaped.
  • Lunar.
  • Trapezoidal.
  • capitate.
  • Pea.
  • trihedral.

The bones that make up the structure of the hand section are rather small, but this feature allows the hand to maintain its flexible and stable properties.

Muscles are the main factor that helps to move human bones. If we talk about those that are in the hand, then they are located on both sides by means of layers. This is necessary for flexion and extension of the palm. With the help of tendons, the muscles are attached to the bone apparatus. Ligaments or tendons are attached to the base of the bone. Only the palm is made up of muscles.

Subdivisions of the muscles of the palmar part:

  • Average.
  • Muscle of the thumb.
  • Muscle of the thumb.

Short muscles as a result give clear and precise movements of the hand, but at the same time greatly complicate its structure.

Leather

The skin here is very heterogeneous. Somewhere it covers the skeleton with a more delicate layer, and somewhere rough. The palm contains thickened skin, but the back side is thinner. All this is due to the fact that the palm itself more often endures various frictions, contact with the outside world, so the thickened version of the skin helps protect muscle tissue.

As for the back, it contains many sweat and sebaceous glands. Collagen and elastin help the skin to give elasticity and firmness. But these proteins tend to break down under the action of ultraviolet rays. Signs such as dry skin of the hands, wrinkling, the appearance of small cracks - all this indicates a decrease in collagen and elastin in the skin of the hands.

Wrist

The wrist is called the part of the upper limb, which is located between the ulna and radius, as well as the metacarpus. Its structure includes 8 bones, which articulate with the bones of the metacarpus and are arranged in two rows. On the edge is a trihedral, scaphoid and lunate bone, connected by articulations. The pisiform bone is located relative to the thumb. It has a special function, namely, it gives strength to the muscles. The ulna and radius form the wrist joint.

Another row includes four small bones. The back is connected to the first row, and the front to the metacarpus. If you look at the wrist from the side of the palm, you can see its concave appearance. The rotational property of the hand is given by the connection between the bones of the wrist and the forearm.

Diseases

Throughout life, a person experiences huge load on your hands. All major departments are included here. Pain in the areas of the hand or wrist can indicate diseases of the articular system or diseases of the internal organs of a person. These symptoms often occur when this part of the arm is injured. If a person has damaged the wrist section, then he will immediately feel a sharp pain, which will subside over time, but the movements of the hand will already be limited. All this is accompanied by painful sensations.

The result of a dislocation of the phalanx of the finger is swelling, deformation of the bone, sometimes pronounced, as well as a decrease in the functionality of the finger. If a fracture of the hand occurs, then large edema occurs, a crunch of fragments is heard, due to which there is pathological mobility, limited movement.

Injuries are treated in a variety of ways. This can be a conservative treatment, which consists in restoring the working capacity of the damaged section, but with the help of an orthosis or plaster, massage, physical procedures. Sometimes surgery is required. It is prescribed for serious fractures. There are other diseases of the hand:

  • tunnel syndrome.

This disease manifests itself as a result of the same type of movements that can constantly manifest itself in a person’s hobby or even in the course of an activity. Pain sensations are initially not expressed, but then acute pain appears. Experts recommend eliminating stress on the arm and keeping it at rest until the pain subsides. Next, you should take warm baths, perform special gymnastics.

This disease has many causes. It can also manifest itself with malnutrition, when metabolism is disturbed, and with various types of fractures, especially when the bones do not grow together correctly.

All this is accompanied by pain in the area of ​​the hand. They occur with a load on a given part of the body, or when the disease progresses steadily, then pain is also experienced in a state of inactivity. With this disease, fine motor skills of the hands deteriorate significantly. Arthrosis is treated with the help of complex therapy, which is carried out according to the doctor's prescription.

This disease occurs when the median nerve is pinched. This occurs when playing musical instruments for a long time, as well as when working at a computer.

The signs are:

  • Periodic numbness of the hand.
  • Pain sensations.
  • Limited finger movement.

With this disease, a person must change his occupation, as well as undergo therapy that is directed against inflammation. In rare cases, surgical intervention is also required.

The causes of this disease are frequent fractures of the arm or its inflammation. The disease is serious, which gradually affects the muscles and bones of the wrist. The blood supply to this area of ​​the body is poor, so the tissue may die over time. Here inflammation occurs, this place is accompanied by pronounced pain, swelling. Very often it is necessary to correct the problem with the help of surgical intervention.

What structures can become inflamed in the wrist?

The wrist has a complex structure, so the process of inflammation can begin from any area. Moreover, some diseases will later become local, while others will spread to the tissues surrounding them.

Inflammation of structures in the wrist

  1. tend to change pathologically, which occurs when their structure is damaged, namely, with dislocations, sprains and fractures. Further, osteoporosis develops, in which the quality of bone tissue decreases.
  2. wrist joint it becomes inflamed, with various types of injuries that cause dislocation of the joint itself, and damage to its structure. Very often, osteoarthritis develops here.
  3. Synovial membrane of the wrist joint usually inflamed with synovitis or arthritis that occurs with fractures and injuries of the wrist.
  4. Ligaments of the wrist belong to a very common case in which they are damaged. All this occurs under large immoderate loads.
  5. Vessels and nerves of the wrist they become inflamed, undergoing pathological changes, during prolonged work with an uncomfortable position of the hand, as well as with heavy weights. Very often, in this case, carpal tunnel syndrome develops.

Which doctor should be consulted?

Of course, it is better not to self-medicate, but to make an appointment with a specialist. In order for the patient to be accurately diagnosed, it is necessary to know where to send a signal for help.

For pain in the hand and wrist, you can contact the following doctors:

  • Neurologist.
  • Family doctor.
  • Traumatologist.
  • Orthopedist.
  • Rheumatologist.
  • Occupational pathologist
  • Therapist.

Conclusion

There are many reasons that can explain the pain in the hands. A person who has noticed pain, swelling or inflammation after a bruise should immediately contact a traumatologist. If the condition is running, then you can go to an appointment with a rheumatologist, a therapist. So that this does not happen and trips to the doctors are not so frequent, you need to take care of your health!

The bones of the arms and hands perform important functions of supporting the upper limbs and providing anchorage for the muscles that move the upper limbs. These bones form joints that allow for a wide range of motion and the flexibility needed to deftly manipulate objects with arm strength. They also provide strength to withstand the extreme strains placed on the shoulders and arms during sports, training, and hard work… [Read below]

  • shoulder joint
  • Brachial bone
  • elbow joint
  • Radius
  • Elbow bone
  • Hand bones

[Beginning at the top] … Comprised of the collarbones and shoulder blades, the shoulder girdle forms the point of attachment between the arms and chest. The clavicle, which gets its name from the Latin word (lat. clavicula), is a long bone that connects the shoulder blade to the sternum (breast bone) of the chest. It is located under the skin in the chest area between the shoulder and the base of the neck. The clavicle is slightly curved like the letter S and is about fifteen centimeters long. The two joints formed by the clavicle are at the sternoclavicular junction with the sternum cell, and at the acromio-clavicular junction with the acromion of the scapula. The clavicles allow the shoulder joint to move in a circle while remaining attached to the bones of the chest.

Behind the clavicle is the scapula, a triangular, 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 articular 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, rhomboids, and rotator cuff muscles.

Humerus

These are just the bones of the upper arm. Long, large bones that run from the shoulder blade to the ulna and radius in the forearm. The proximal end of the humerus is a round structure that forms the ball for the shoulder joint. At its distal end, the humerus forms a broad, cylindrical structure that forms the internal hinge of the elbow joint from the ulna and radius. The pectoral, deltoid, 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 section is at its proximal end and significantly narrowed at the distal one. 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 into the humerus and forms the bony tip of the elbow. At its distal end, the ulna forms the radiocarpal joint with the radius 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 rotator cuff of the elbow joint, which permits rotation of the forearm and hand. At its 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 as 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 carpal joints form many small joints, sliding over each other to give extra flexibility to the wrist and hand.

Five long, cylindrical metacarpal bones support the shape of the palm. Each metacarpal 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 when pressing the thumb and little finger together.

phalanges

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 hands require a balance of strength and dexterity to perform a variety of tasks such as lifting weights, swimming, playing a musical instrument, and being able to write.
The arm joints and muscles provide a wide range of motion while maintaining the strength of the upper limbs. Like all bones in the body, the bones of the upper limb help the body maintain homeostasis by storing minerals and fats and by producing blood cells in the red bone marrow.

The arm skeleton consists of the humerus, forearm bones, and hand bones.

Skeleton of the hand. Front view. Fig A: 1 - collarbone; 2 - scapula Fig B: 1, 2 - connection of the articular surface of the acromial end of the clavicle with the articular surface of the scapular spine; 3 - head of the humerus; 4 - articular cavity of the scapula

Skeleton of the hand. Back view.

Skeleton of the hand. Inner side

Skeleton of the hand. outer side

I Humerus

Brachial bone about one-fifth of a person's height in length. At the top, it forms a spherical thickening, the head, which articulates with the glenoid cavity of the scapula, forming the shoulder joint. Below the head, on the anterior surface of the humerus, there are two protrusions: one is located outward and is called the large tubercle - the crest of the large tubercle stretches down from it; the other protrusion is located medially and is called the lesser tubercle - the crest of the lesser tubercle extends from it. On the outer side of the humerus, just above the middle, is the deltoid tuberosity, where the tendon of the deltoid muscle is attached. Below, the humerus is expanded from the outside inward, and flattened from front to back: there are two articular surfaces covered with cartilage: one is spherical - the capitate elevation, lies outwards, the other, blocky, is located inward and is called a block; the surface of the block passes into the coronary fossa lying in front and into the cubital fossa lying behind. Here, outside and inside, there are two protrusions: the outer epicondyle and the inner epicondyle.

Brachial bone. 1 - articular head; 2 - upper large tubercle; 3 - anterior small tubercle; 4 - intertubercular furrow; 5 - neck of the humerus; 6 - the body of the bone; 7 - cubital fossa; 8 - radial fossa; 9 - external epicondyle; 10 - capitate elevation; 11 - articular block; 12 - internal epicondyle; 13 - semilunar fossa (for the olecranon)

The humerus is located inside the muscles of the shoulder in such a way that its lower end almost adjoins the back surface of the shoulder. The humerus is easy to feel: its upper end protrudes under the muscle if the lower end of the arm is folded back. The body of the humerus is palpated in the middle of the outer side of the shoulder; the inner epicondyle is clearly visible in any position of the hand; when the arm is strongly bent at the elbow, both epicondyles and even the depression between them, corresponding to the cubital fossa, clearly protrude; when the arm is extended, this depression is closed by the ulna, and the external epicondyle goes into the depths of the so-called beauty fossa, where it can be felt.

II Bones of the forearm

If you look at your hand or the hand of the sitter, when it is half-bent at the elbow and turned palm up, you can find a bone on the back of the forearm that starts at the top with a protrusion (called the elbow in everyday life) and stretches under the skin to the hand, where it ends with a slight elevation lying with sides of the little finger. This bone is called ulnar. Here, near the hand, another bone located closer to the thumb is found, which is difficult to feel higher along the forearm, and then stretches among the muscles; its upper end is located in the depths of the "fossa of beauty" below the outer epicondyle of the shoulder; if you put your fingers there and twist with a brush, you can feel how this end turns. This bone is called ray. In this case, both bones, the radius and the ulna, lie parallel, that is, in the position of supination. If, then, the hand is turned with the palm down, the radius will move simultaneously with the hand, and it will lie across and over the ulna. This movement is called pronation, and the position is called the pronation position. The return of the hand and radius to its original position is called supination.

Main bone forearms - ulnar(it is longer than the beam). At its upper end, resembling a wrench, there is a large lunate notch, through which the ulna articulates with the block of the humerus; at the top, the ulna ends with the olecranon, or elbow; anteriorly, below the semilunar notch, the coronoid process protrudes. Just below the large lunate notch, on the outer side of the ulna, there is a small lunate notch - an articular platform for articulation with the head of the radius, and nearby, on the front surface, protrudes the tuberosity of the ulna - the place of attachment of the shoulder muscle. Below, closer to the hand, the ulna narrows and forms a head at the end, on which there is a cylindrical articular platform for articulation with the lower end of the radius; the styloid process departs from the head downwards.

Bones of the forearm. A - radius; B - ulna 1 - head of the radius; 2 - the neck of the radius; 3 - radial tuberosity; 4 - styloid process; 5 - olecranon olecranon; 6 - concave surface of the olecranon, divided by a ridge; 7 - coronoid process; 8 - styloid process; 9 - base of the epiphysis; 10, 11 - articular surfaces separated by a ridge; 12 - head of the ulna; 13 - small crescent notch for articulation with the head of the beam; 14 - articular fossa of the radius; 15 - semilunar fossa

Radiation bone narrow at the top, forms a cylindrical head, its lower end is widened; on it, from the side of the thumb, the styloid process protrudes downward. In front, below the head, there is a radial tuberosity - the place of attachment of the tendons of the biceps muscle. The radius lies next to the ulna, articulating with it by two joints, for which there are articular platforms on the head and lower end of the bone. Above, on the head, there is a spherical articular notch, with the help of which the radius articulates with the capitate eminence of the humerus. At the lower extended end of the radius, facing the wrist, there is also an articular platform, which serves to articulate with the wrist.

The ulna and radius together with the humerus form the elbow joint. When the arm is extended at the elbow joint, the forearm is supinated, the bones of the shoulder and forearm form an obtuse angle, open outward, which is why the shoulder and forearm are angled in this position, the apex of this angle is the internal condyle of the shoulder (check for yourself). Three articulations take part in the formation of the elbow joint: the trochlear articulation between the ulna and the humerus, the spherical articulation between the radius and the humerus, and the cylindrical articulation between the upper ends of the radius and the ulna.

Below, between the lower ends of the ulna and the radius, a cylindrical joint is also formed. Due to this, pronation and supination occur in the upper and lower cylindrical joints. Below, the radius descends below the ulna. With its expanded lower end, on the side of the ulna, a triangular cartilage is fused, which increases the articular area of ​​​​the radius that articulates with the wrist. This cartilage, movably articulating _ above with the ulna, lies between the ulna and the wrist, separating them from each other. Thus, the hand with its upper section (wrist) articulates only with the radius, and the articular platform formed by the radius and triangular cartilage lies somewhat obliquely to the forearm.

ІІІ Skeleton hand

The skeleton of the hand is made up of the wrist, metacarpus, and phalanges of the fingers. The bones of the hand are close to its back surface; if you start probing the skeleton of the hand from your fingertips, it is easy to understand that the thumb contains two, and the rest three phalanges. On the back of the hand from the base of the fingers to the forearm, you can easily feel five long bones arranged in a fan-like manner, and the first bone, corresponding to the thumb, can move in different directions, and the rest are inactive; these metacarpals together form the metacarpus. The stretchable and compressible area between the forearm and the pastern is called the wrist. Her skeleton is formed by eight carpal bones lying in two rows. In the first (upper) row, if you count from the thumb to the little finger, there are bones: scaphoid, lunate, trihedral and pisiform; in the second row: large polyhedral, small polyhedral, capitate and hook-shaped.

A - from the palmar side; B - from the rear: 1 - scaphoid k., 2 - lunate k., 3 - trihedral k., 4 - pea-shaped k., 5 - large polygonal k., 6 - small polygonal k., 7 - capitate k., 8 - hook-shaped k., 9 - metacarpal k., 10 - heads of metacarpal k., 11 - phalanges of the fingers, 12 - radial elevation of the wrist

Part of bones wrists protrudes to the surface of the brush. From the side of the palm, at the base of the muscular eminence of the little finger, a pisiform bone protrudes noticeably; the tendon of the ulnar flexor approaches it. At the base of the muscles of the thumb, the radial eminence of the wrist, formed by the navicular bone and the large polygonal bone, is palpable and partly protrudes. In addition, the large polygonal and navicular bones can be felt from the back of the wrist between the base of the I metacarpal bone and the radius, with a sharp deviation of the hand towards the little finger, when the navicular bone comes out of the depth of the wrist joint and thereby lengthens the distance between the thumb and the radius.

The scaphoid, lunate and triquetral bones, that is, the upper row of carpal bones (except for the pisiform), together form a common articular platform for articulation with the radius. This joint is the ovoid wrist joint.

The wrist joint has two axes of rotation: long and short. The long axis is located corresponding to the articular area of ​​​​the radius: flexion and extension movements occur around this axis.

The short axis crosses the long one in the anteroposterior direction; there are movements around it: abduction of the brush to the outside (towards the thumb) and bringing the brush inward (towards the little finger). In addition, a circular motion is possible in the wrist joint, when the hand describes a circle with the ends of the fingers.

The bones of the wrist and metacarpus are interconnected by inactive intercarpal and metacarpal-carpal joints, making it possible to stretch and compress the outer surface of the wrist area. But one of the bones, a large polygonal one, is an exception: connected inactively with neighboring bones, it forms with the I metacarpal bone a very mobile saddle-shaped biaxial joint, which forms the basis of various movements of the thumb.

The bones of the hand. Wrist bones. Top row: 1 - scaphoid; 2 - lunar; 3 - trihedral; 4 - pea-shaped Lower row: 5 - large polygonal; 6 - small polygonal; 7 - capitate; 8 - hooked bones of the metacarpus (a - d). Each bone consists of a body that thickens towards the ends, passing from above to the base (from the side of the wrist), and from below to the head (from the side of the phalanges). Phalanges of the fingers: 1 - main; 2 - intermediate; 3 - nail Fingers are indicated by Roman numerals, where the count comes from the thumb.

metacarpus consists of five bones, which are named, counting in order from the thumb, with Roman numerals: I - metacarpal bone, corresponds to the thumb, II - forefinger, etc. The metacarpals are widened above and below. The upper ends that articulate with the wrist are called bases, the lower ends that articulate with the phalanges of the fingers are called heads; the heads are spherical and protrude sharply when the hand is clenched into a fist; the heads of the II-V metacarpal bones diverge fan-shaped and are interconnected by transverse ligaments. These four bones are held together and form the base of the palm; I metacarpal bone, on the contrary, has great mobility; driven by the muscular apparatus, it can approach the rest of the bones or move away from them, changing the shape of the hand.

Fingers are indicated by Roman numerals: thumb - I, index finger - II, etc. The skeleton of the fingers is formed by phalanges, which are also marked with Roman numerals, counting from the metacarpus: I, II and III phalanges, or the main, intermediate, nail; I phalanx is larger than the second, and II is larger than the third. The phalanges of the fingers are interconnected by block-like uniaxial interphalangeal joints, in which flexion and extension movements are possible. The main phalanges of the II-V fingers, articulating with the heads of the metacarpal bones, form metacarpophalangeal biaxial joints, in which movements of flexion and extension are possible, movements to the side - abduction and adduction, as well as circular movements, when the ends of the fingers describe a circle. The main phalanx of the first finger articulates with the first metacarpal bone with a uniaxial metacarpophalangeal joint; in this joint, only flexion and extension movements are possible; thus, the thumb has the greatest mobility in the metacarpal-carpal joint between the I metacarpal bone and the large polygonal.

The movable connections between its many bones allow the hand to perform many different tasks. So, let's take a closer look at the unique hand joints.

The hand is the distal (distant) large structural element of the upper limb girdle. Anatomically, it begins with a complex articular complex that connects the radius to the bones of the wrist.

Wrist joint complex

This joint provides the optimal position of the hand for its grasping functions. Structurally, it is a tandem of two joints:

  1. The wrist is formed by the far end of a fairly large bone of the forearm (radius) and the near (proximal) surfaces of the bones of the wrist.
  2. The mid-carpal is located between two rows of small carpal bones.

Due to additional movements between the far ends of the forearm, the possibilities for orienting the hand in space are significantly expanded. In this area, the epiphyses of the radius and ulna are connected using the lower radioulnar joint. It does not apply to the hand, but significantly expands its functionality: pronation and supination (the ability to turn the hand) are added.

Thus, the human hand acquires abilities that no other skeletal formation can boast of.

wrist joint

According to the shape of the articular surfaces, it belongs to the ellipsoid. We describe the main anatomical characteristics:

  1. From the side of the forearm, it forms the lower end (epiphysis) of a rather large radius.
  2. On the side of the wrist, there are three relatively small bones of the first (proximal) row: scaphoid, trihedral, and lunate.
  3. On the carpal side, all three bones are covered with a continuous hyaline plate, forming a single articular surface.

Mid-carpal joint

Anatomically, this articulation can hardly be called a typical joint. It is located between two rows of bones of the wrist, which form the articular surfaces of this joint.

The lunate bone is of key importance for movements in this structure. It plays the role of a certain column or axis, around which movements are made. At the same time, their amplitude is limited, and stability is ensured by the ligamentous apparatus. The ligaments are so strong that in case of injury, any of the small bones of the wrist would rather dislocate or break than their connective tissue joints would break.

Characteristics of movements in the wrist joint

The dense arrangement of bony surfaces means that all the joints of the wrist take part in every movement. The anatomical features of the complex are reflected in the range of motion in each of its departments.

Thus, flexion of the hand by 50˚ provides the wrist joint and by 35˚ - the midcarpal articulation. In extension, on the contrary, the mid-carpal joint (50˚) prevails over the wrist joint (35˚).

The wrist, with its two-row structure and small bones, is better imagined as a kind of bag filled with small stones.

Then it becomes easier to understand the physiology of movements and the features of the interaction between the bones, in which the ligaments take an active part. Their role is to ensure the stability of the joint.

Thus, the hand, as an integral part of the hand, can be oriented in space in the most favorable position for the required activity.

Anatomical and physiological features of the hand

To effectively perform a grasping function, the hand must be able to change shape. Leaning on a flat surface, the brush flattens. If you need to grab and hold a large object, the brush forms a concavity. In this case, three arches appear, located in different planes:

  1. The transverse arch is formed due to the concavity of the wrist.
  2. The longitudinal arch is formed by the bones of the wrist, fanned out from the metacarpophalangeal joints.
  3. The third vault is inclined. It appears as a result of the opposition of the thumb relative to the rest of the fingers. So there is a palmar recess.

The ability of the hand to create such a grasping device is provided by the movable joints between the carpal and metacarpal bones, the metacarpus and the first phalanges of the fingers, and the interphalangeal joints.

Joints of the bones of the wrist and metacarpus

They are formed by the distal (distal) articular surfaces of the carpal and near (proximal) metacarpal bones. These joints are held by strong ligaments, participate in the formation of the arch of the palm and differ from each other in mobility.

From the side of the wrist, the trapezoid bone is simultaneously connected to the I and II metacarpal bones. In this case, the second carpometacarpal joint is very limited in movement. What can not be said about V (between the hook-shaped bone of the wrist and V metacarpal).

Of particular interest is the I trapezoid-metacarpal joint. Its peculiarity is that it allows the thumb to oppose the rest of the fingers.

This is a saddle joint. The capsule is not stretched and allows for movements with great amplitude and freedom. At the same time, it is the cause of frequent dislocations of the thumb.

Connection of the metacarpophalangeal joints

The joints are condylar (saddle-shaped) in shape. Movements in them are possible in two mutually perpendicular directions (flexion and extension). To a lesser extent, the possibility of adduction and abduction is presented.

The metacarpal head has a biconvex surface, the base of the proximal phalanx is biconcave, but its area is much smaller. This structure allows for flexion and extension of the fingers with a large amplitude.

If the articular surfaces more fully corresponded to each other, then this would reduce the ability to shift them relative to each other and reduce the functionality of the hand.

In addition to flexion and extension, the metacarpophalangeal joint allows you to make fairly sweeping movements to the sides (adduction and abduction). And the thin and complex muscular-tendon apparatus turns them into circular ones.

Most of all, the ability to lateral displacement is expressed in the second finger. That is why it is called index.

It is noteworthy that if the fingers are acted upon from the outside (forcibly), the amplitude of passive movements becomes greater than active ones. They can be done with the help of your own muscles of the hand (100˚ or more passively versus 60–90˚ actively).

Interphalangeal joints

These movable bone joints create the ability for the human hand to hold objects (tools). This property is reinforced by the thumb, which is opposed to the rest and serves to press the object to the palm and securely hold it.

According to the shape of the articular surfaces, these are spherical joints with the ability to move only in one plane (flexion and extension).

The head of the phalanx is block-shaped, concavity in the middle. On the basis of the next phalanx there are two shallow surfaces covered with hyaline cartilage, with a central crest in the middle.

The peculiarity of this joint is the amplitude of flexion movements of more than 90˚. Large extensor movements are hindered by the ligamentous apparatus of the finger phalanges and interphalangeal joints. An exception is the distal phalanges, in which active extension is possible up to -5˚, and passive extension up to -30˚.

The structure of the ligaments and tendons of the hand is such that the ring finger and little finger automatically tilt away from the thumb when bent. This mechanism allows for greater opposition of the fingers and increases the efficiency of the grip of the palm.

Summarizing the above

No other living creature on planet Earth is capable of those manipulations (by the way, manipula in Latin means hand) that a human hand allows. It becomes clear what makes the human hand an amazing and unique creation of evolution.

Such wonderful opportunities are provided to her by the structure of her own skeleton and unique joints of her kind.