The arm muscles include the muscles of the forearm and shoulder. The shoulder muscles are divided into two categories: flexors, or the anterior muscle group, and extensors, the posterior group.

Anterior muscle group The shoulder is formed by three main muscles:

• coracobrachial;
• two-headed;
• brachial muscle.

Extensors in turn are represented by two muscles:

• elbow muscle;
• triceps brachii muscle.

Shoulder flexors

Coracobrachialis muscle (m.coracobrchialis)

The coracobrachialis muscle belongs to the flexor group. It originates from the top of the coracoid process, and its other end, passing into a flat tendon, is attached to the humerus, just below the crest of the lesser tubercle. It is attached approximately there.

Main functions: The coracobrachialis muscle is involved in flexion of the shoulder at the shoulder joint. It brings the shoulder toward the body and also rotates the shoulder outward during pronation. When the shoulder is fixed, the m.coracobrchialis pulls the scapula forward and downward.

Biceps - biceps brachii (m.biceps brachii)

As the name suggests, the biceps brachii muscle has two heads. One of these heads is long, the other is short. The long head starts from the supraglenoid tubercle of the scapula. The short head begins in the same place where the coracobrachialis muscle originates - at the coracoid process. Fusing at the level of the shoulder, both heads form a spindle-shaped muscle, which turns into a tendon, which is attached to the tuberosity of the radius.

Main functions: The biceps is involved in flexing the shoulder joint and flexing the forearm at the elbow. When the forearm is rotated inward, the biceps brachii muscle helps return it to its original position.

Brachial muscle (m.brachialis)

The brachialis muscle has a deeper location than the biceps, however, it also belongs to the anterior shoulder group. The origin of the muscle is two-thirds of the lower surface of the humerus, limited by the deltoid tuberosity and capsule of the elbow joint, as well as the lateral and medial intermuscular septum of the shoulder. The brachialis muscle ends on the tuberosity of the ulna. The deeper part of the brachialis tendon is woven into the capsule of the elbow joint.

Main function: The brachialis muscle flexes the forearm at the elbow joint.

Shoulder extensors

Triceps brachii (m.triceps brachii)

The triceps brachii is a large, powerful muscle that is divided into three heads and is located on the back of the shoulder. The long head begins on the scapula, the medial and lateral heads begin on the humerus.

Main functions: The triceps brachii muscle is an extensor muscle; it is involved in extension of the elbow joint of the forearm. In addition, through the long head, the triceps also extends the shoulder and brings it towards the body.

Elbow muscle (m.anconeus)

The anconeus muscle is triangular in shape and belongs to the extensor group. The origin of the m.anconeus lies on the posterior surface of the lateral epicondyle of the humerus. The olecranon muscle is attached to the posterior edge of the ulna.

Main functions: The elbow muscle extends the arm at the elbow.

Forearm muscles

The muscles of the forearm, like the muscles of the shoulder, are represented by extensors and flexors. Many muscle groups of the forearm are multi-articular muscles, their action is aimed at movements in joints such as the wrist, elbow, finger joints and hand. The largest muscle of the forearm is the brachioradialis, which is responsible for flexing the limb at the elbow joint.

64. Muscles that flex and extend the hand and fingers.

Bend the hand: flexor carpi ulnaris, flexor carpi radialis, flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus, palmaris longus.

Flexor carpi ulnaris starts from the medial epicondyle of the humerus, from the ulna and the fascia of the forearm. The distal end reaches the pisiform bone, to which it is attached. From the pisiform bone to the hamate and to the 5th metacarpal bones there are ligaments that are a continuation of the traction of this muscle.

Flexor carpi radialis starts from the medial epicondyle of the shoulder and the intermuscular septum, the muscle passes to the hand under the flexor retinaculum ligament and attaches to the base of the 2nd metacarpal bone. Being a multi-articular muscle, it is involved not only in the movements of the hand, but also in flexing the forearm at the elbow joint.

Flexor digitorum superficialis starts from the medial epicondyle of the humerus, as well as from the ulna and radius. It has four tendons that pass to the hand through the carpal canal, located under the flexor retinaculum ligament, and reach, each splitting into two legs, the lateral surfaces of the middle phalanges of the 2-5th fingers, to which they are attached. The function of this muscle is to flex the middle phalanges. Being multi-articular, the muscle also causes flexion in all joints of the hand, except for the distal interphalangeal joints.

Flexor digitorum profundus lies directly on the anterior surface of the ulna and on the pronator quadratus; starts from the upper two thirds of the palmar surface of the ulna and partly from the interosseous membrane. It is divided into four tendons, which pass in the carpal canal to the distal phalanges of the 2nd-5th fingers of the hand through the splitting of the tendons of the superficial flexor digitorum. Being a multi-articular muscle, it produces flexion in all joints of the hand, including the distal interphalangeal joints. The tendons fan out on the hand towards the fingers, due to which this muscle not only flexes the fingers, but also adducts them.

Flexor pollicis longus- a single-pinnate muscle with a fusiform shape. It starts from the palmar surface of the radius, passes through the carpal tunnel in a separate synovial sheath and reaches the distal phalanx of the thumb, to which it is attached. The muscle produces flexion in all joints around which it passes (in particular, it flexes the distal phalanx of the thumb).

Palmaris longus muscle is not constant. Starting from the medial epicondyle of the humerus and from the fascia of the forearm, this muscle is located on its anterior side so superficially that during contraction it is easy to see it under the skin and palpate the tendon. Attaching to the palmar aponeurosis and pulling it, with strong contraction it can also take some indirect part in flexing the fingers.

Unbend the hand: extensor carpi radialis longus and brevis, extensor carpi ulnaris, extensor digitorum, extensor pollicis longus, extensor of the little finger, extensor of the index finger.

Extensor carpi radialis longus starts from the lateral edge of the humerus, the intermuscular septum and the lateral epicondyle, passes under the extensor retinaculum ligament and the extensor pollicis longus tendon and is attached to the base of the 2nd metacarpal bone. Due to the fact that the resultant of this muscle passes very close to the transverse axis of the elbow joint, its participation in flexion of the forearm is insignificant. Being a strong extensor of the hand, it also produces some abduction during isolated contraction.

Extensor carpi radialis brevis starts from the lateral epicondyle of the humerus, fascia of the forearm and attaches to the base of the 3rd metacarpal bone. Being an extensor of the hand, the muscle also abducts it.

Extensor carpi ulnaris originates from the lateral epicondyle of the humerus, collateral radial ligament and fascia of the forearm. Descending onto the hand, the muscle passes between the head and the styloid process of the ulna and attaches to the base of the 5th metacarpal bone. Being an extensor of the hand, the extensor carpi ulnaris also adducts it.

Flex the thumb: flexor pollicis longus, flexor pollicis brevis.

Extensor digitorum originates from the lateral epicondyle of the humerus, radial collateral ligament, annular ligament of the radius, and fascia of the forearm. In the middle of the forearm, this muscle passes into tendons running under the extensor retinaculum ligament to the dorsum of the proximal phalanges of the 2-5th fingers. Each tendon, in turn, has three legs, of which the middle one is attached to the middle phalanx, and the two lateral ones reach the distal phalanx of the fingers.

Extensor pollicis longus starts from the posterior surface of the ulna and radius, the interosseous membrane of the forearm and attaches to the distal phalanx of the thumb. The tendon of this muscle passes under the extensor retinaculum ligament in a separate channel, crossing the tendons of the extensor carpi radialis. By extending the distal phalanx, the muscle simultaneously pulls the thumb back somewhat. If it is fixed, then the muscle participates in the abduction of the entire hand.

Extensor of the little finger starts from the lateral epicondyle of the humerus, radial collateral ligament, annular ligament of the radius and fascia of the forearm, goes down and attaches to the dorsal aponeurosis of the 5th finger. By extending this finger, the muscle also extends and slightly adducts the entire hand.

Extensor index finger starts from the dorsum of the ulna and the interosseous membrane. This muscle, with its tendon, merges with the extensor tendon of the digitorum, which goes to the 2nd finger, reaches the dorsal aponeurosis of the index finger and is attached to its distal and middle phalanges. It extends the index finger and also promotes extension of the entire hand.

Also in progress flexion and extension of fingers muscles involved: extensor pollicis brevis, lumbrical muscles, palmar interosseous muscles, dorsal interosseous muscles, abductor pollicis brevis, flexor pollicis brevis, oppons pollicis brevis, adductor pollicis brevis, palmaris brevis muscle, abductor digiti minimi, flexor digiti minimi brevis, opponens minimi muscle.

Extensor pollicis brevis starts from the posterior surface of the ulna and radius, attaches to the proximal phalanx of the thumb, which it extends, simultaneously abducting the entire finger. If the finger is fixed, then the muscle is involved in abduction of the entire hand.

Vermiform muscles begin from the tendon of the deep flexor digitorum. These muscles go to all fingers, with the exception of the 1st. They are attached to the dorsal aponeurotic extensions of the proximal phalanges. The function of these muscles is that they flex the proximal phalanges of the 2-5th fingers.

Palmar interosseous muscles(there are 3 of them) are located in the spaces between the metacarpal bones of the 2-5th fingers and start from these bones. They are attached to the articular capsules of the metacarpophalangeal joints and to the dorsal aponeurosis of the 2nd, 4th and 5th fingers. By bending their proximal phalanges, these muscles simultaneously lead these fingers to the middle finger.

Dorsal interosseous muscles four in number are located in the spaces between the metacarpal bones. The place of their origin is the lateral surfaces of the metacarpal bones facing each other. Reaching the dorsal surface of the proximal phalanges, they are woven with thin tendons into the aponeurotic stretch of the extensor fingers. The function of these muscles is that, while bending the proximal phalanges of the 2-5th fingers, they simultaneously contribute to the extension of the middle and distal phalanges of these fingers. Additionally, they retract the 2nd and 4th fingers away from the 3rd and tilt the 3rd finger toward both the radius and ulna.

Abductor pollicis brevis muscle, has an extensive origin on the flexor retinaculum ligament and on the scaphoid bone. Attached to the proximal phalanx of the thumb, it promotes its abduction.

Flexor pollicis brevis starts from the flexor retinaculum ligament and trapezius bone. This muscle is attached to the sesamoid bone and, bending the 1st phalanx of the thumb, promotes (due to the tension of the antagonists) the extension of its 2nd, distal, phalanx. The muscle is also involved in opposing the thumb.

The muscle that opposes the thumb to the hand starts from the flexor retinaculum ligament and trapezium bone, and attaches to the 1st metacarpal bone. Its function is that it opposes the thumb to all the others.

Adductor pollicis muscle, has two heads - transverse and oblique. The transverse one starts from the palmar surface of the body of the 3rd metacarpal bone, the oblique one - from the base of the 2nd and 3rd metacarpal bones and the capitate bone. The muscle attaches to the sesamoid bone located in front of the metacarpophalangeal joint of the thumb, as well as to the capsule of this joint and the proximal phalanx of the finger. Its function is that, by bringing the thumb to the median plane of the palm, it promotes its opposition to the other four fingers.

Palmaris brevis starts from the palmar aponeurosis and attaches to the skin. When clenching the hand into a fist or when striking with the palmar surface of the hand, this muscle helps protect the vessels and nerves running along the ulnar side from the front surface of the forearm to the hand.

Abductor digiti minimi muscle begins on the pisiform bone and attaches to the base of the proximal phalanx of the 5th finger. The function of the muscle is to abduct this finger, flex its proximal phalanx and extend the middle and distal phalanges.

Flexor digiti brevis starts from the flexor retinaculum ligament and hamate bone and attaches to the ulnar edge of the base of the proximal phalanx of the 5th finger. The function of the muscle is to flex and adduct.

Opponus little finger muscle, begins together with the previous muscle, and is attached to the body and head of the 5th metacarpal bone, which it bends slightly and brings closer to the middle of the palm.

Muscles of the hand, right (tendons of the superficial flexor digitorum are partially removed)

1 - flexor retinaculum; 2 - muscle that abducts the little finger; 3 - short flexor of the little finger; 4 - tendons of the deep flexor of the digitorum; 5 - muscle opposing the little finger; 6 - lumbrical muscles; 7 - tendons of the superficial flexor of the fingers; 8 - adductor pollicis muscle; 9 - flexor pollicis longus tendon; 10 - short muscle that flexes the thumb; 11 - short muscle that abducts the thumb.

Sport is the key to health and visual attractiveness, so these days more and more people are setting aside time to visit gyms. The most attention and concern for beginners is usually upper body training. Every day, attention is paid to exercises that pump up the biceps, triceps and other arm muscles. At the same time, the technology often remains simply terrible. All this comes from ignorance of the anatomical structure of human muscles. A deep understanding of the process and degree of involvement of a particular muscle in an exercise will allow you to maximally load the target muscle and achieve the best result.

What is included in the concept of “arm muscles”?

Anatomically, the muscles of the human arm can be divided into two main groups:

1. Shoulder muscles - originate from the deltoid and are located up to the elbow muscle.

2. Forearm muscles - start from the elbows and include all the muscles to the fingertips.

The structure of the human shoulder

The shoulder muscles are divided into the following groups:

1. Arm flexors (anterior shoulder muscles), which include the brachialis, coracobrachialis, and biceps muscles.

2. Arm extensors (posterior shoulder muscles), which include the triceps and anconeus muscles.

Arm flexors

Considering in more detail the anatomy and functional purpose of this element, it should be noted that the brachialis muscle ensures flexion of the forearm. The biceps, also called the biceps brachii muscle, is designed for flexion of the upper limbs at the elbow and shoulder joints, as well as for rotational movements of the forearm. It consists of a short and a long head. The coracobrachialis muscle is directly involved in flexion and rotation of the arm at the elbow and shoulder joints.

Arm extensors

The main extensors are the triceps - the arm muscles, which are also called the triceps brachii muscles. They consist of a long, medial and lateral head. The main functions of the triceps are extension of the forearm at the shoulder and elbow joints, as well as adduction of the upper limbs to the body. The anconeus muscle helps the triceps in extending the arm at the elbow joint.

The structure of the muscles of the forearm

The muscles of the forearm are similar in their division to the shoulder muscles (they are also divided into anterior and posterior), while each of the given subgroups is divided into deep and superficial layers of muscles.

Front group

Let's consider the muscles of the arms of the superficial layer of the anterior group, which include the following elements:

2. Flexor carpi radialis - performs functions adjacent to the flexor ulnaris and also pronates the forearm.

3. Pronator teres - a smaller muscle that completely repeats the functions of the previous two.

4. Superficial flexor of the fingers - takes part in flexion of the elbow joint and hand, as well as the middle phalanges.

5. Palmaris longus muscle - controls the palm and takes part in flexion of the elbow joint.

The deep layer is represented by the following muscles:

1. Flexor pollicis longus - flexes the thumb and nail phalanx.

2. Flexor digitorum profundus - flexes the hand and extreme phalanges.

3. Pronator quadratus - the main pronator of the forearm.

Back group

The superficial layer of the posterior group consists of the ulnar, extensor carpi brevis and longus, extensor fingers, as well as the brachioradialis muscle, which flexes the upper limb at the elbow, rotates and pronates the forearm. The deep layer consists of the extensor pollicis longus and brevis and the abductor pollicis longus muscles, which abduct and extend the human thumb. Also belonging to this layer are the extensor of the index finger, the functions of which are clear from its name, and the supinator, which controls the hand and forearm.

Carpal muscles

The human hand consists of nine muscles, the main functions of which are flexion and extension of the fingers, as well as ensuring their static positions: short flexors of the thumb and little finger, abductor muscles of the thumb and little finger, muscles that oppose the thumb and little finger, muscles that lead to movement thumb, lumbrical and interosseous muscles.

Thus, the human hands contain many different muscles that have a huge number of functions.

Training muscle groups of the upper limbs

How to properly train arm muscles? Human anatomy allows upper limbs responds quite well to training. Each muscle has specific movements, and therefore requires specific pumping exercises. Thus, the biceps is responsible for bending the arm, so various exercises for lifting weights (barbells, dumbbells) by bending the arm at the elbow joint from various provisions(sitting, standing). The triceps works to straighten the arm. The exercises involve applying effort at the moment when the arm muscles are straightened (push-ups, overhead extensions, and so on). For the forearm muscles, wrist flexion and extension, as well as exercises with an expander (or rubber ball), are best suited.

A pleasant feature of the arm muscles is their ability to rapid recovery after training, which makes pumping more frequent. But when training your arms, just like any other muscle group, the main thing is not to overdo it, otherwise you can achieve the opposite result - constant fatigue and even injuries.

ENCYCLOPEDIA OF MEDICINE

ANATOMICAL ATLAS

Extensor muscles

When worked in concert with the flexor muscles, the extensor muscles of the forearm provide a wide range of motion and significant mobility.

wrist, hand and fingers.

The posterior group includes the muscles that extend and straighten the wrist and fingers. The extensor muscles are separated from the flexor muscles by the radius and ulna bones, a dense interosseous membrane, and are also surrounded by a layer of thin connective tissue - the fascia of the forearm.

FUNCTIONS OF THE EXTENSOR MUSCLES The extensor muscles provide a wide range of motion to the wrist and hand. These muscles can be divided according to their functions into three groups.

■ Muscles that provide movement of the hand or wrist; they extend the wrist, pull the hand back, and provide lateral flexion of the hand.

■ Muscles that extend the fingers with the exception of the thumb.

■ Muscles that extend the thumb and ensure its abduction to the side.

SUPERFICIAL EXTENSOR MUSCLES

■ Extensor carpi radialis longus

Extends and abducts the hand towards the wrist (bends away from the little finger).

■ Extensor carpi radialis brevis

This muscle together with the extensor carpi radialis longus

Provides stability to the wrist joint when the four fingers are flexed.

■ Extensor carpi ulnaris

This long, thin muscle is located along the inner side of the forearm. Extends and abducts the wrist, and also participates in clenching the hand into a fist.

■ Extensor digitorum

This muscle is the main extensor of the four fingers. It forms a relief on the back of the forearm.

■ Extensor muscle of the little finger

This muscle runs along the extensor digitorum and is involved in extension of the little finger.

■ Brachioradialis muscle

Despite the fact that the brachioradialis muscle is part of the extensor muscle group, it also provides flexion of the forearm at the elbow joint. It returns the forearm to its original position when it pronates or supination.

The superficial layer of the extensor muscles is located close to the skin. They are all held together by a band of connective tissue called the extensor retinaculum.

Superficial extensor muscles

Synovial cyst of the wrist (ganglion)

The long tendons of the forearm extensor muscles run along the back of the wrist. They are located in synovial sheaths (fluid-filled membranes) that moisturize and protect the tendons from friction with bone.

A thin-walled cyst containing a clear, viscous fluid may form in one of the tendon sheaths. In this case, a round, painless formation is identified on the dorsum of the wrist, which can vary in size. It is called a ganglion or hygroma. If the ganglion does not resolve spontaneously, it is removed surgically.

A ganglion is a cyst of the synovial tendon sheath. Most often it is localized on the wrist joint. Despite the fact that the ganglion can reach significant sizes, it usually does not cause any complaints.

Brachioradialis muscle

Flexes the forearm at the elbow joint.

Extensor carpi radialis longus

Attaches to the humerus; extends and abducts the hand towards the wrist (from the midline of the body).

Extensor carpi radialis brevis

A short muscle that serves to stabilize the wrist joint when the four fingers are in a flexed position

Extensor of the little finger

Participates in extension of the little finger

Extensor retinaculum

A connective tissue band surrounding the back of the wrist.

Many sports actively involve the extensor muscles of the forearm. Players in table tennis A wide range of motion ^B* of the wrist is especially necessary.

Extensor carpi ulnaris

It is attached to the lateral epicondyle of the humerus and the lateral surface of the ulna, passes down and connects with the other end to the base of the fifth metacarpal bone.

Extensor digitorum

It is the main extensor of the fingers.

We all move actively: we walk, walk, run, jump, climb and fall. Without a developed muscular system, all these movements will be very difficult. main part The work falls on the flexor and extensor muscles.

These are constantly opposing antagonists. Their resistance is inherent in the nerve centers that control their activities. The movement centers located in the brain of the head give out signals. They go to motor neurons, nerve cells located in the brain of the back, and then along the longest processes to the necessary muscles.

The centers that send signals to antagonists are located in radically different states. When the flexor center is excited, the extensor counterpart relaxes.

Flexors and extensors work by straining. They move the entire body or its individual elements, doing work dynamically when running, walking or lifting objects. Static work is performed while maintaining a particular pose and holding an object.

Both activities can be performed by the same muscles.

By contracting, they act like levers on the bones. Every joint moves thanks to muscle mass, fastened on the sides. Which muscle is a flexor and which is an extensor depends on the situation.

When the arm bends, the 2nd head muscle of the shoulder contracts, and the 3rd head muscle relaxes. Typically, extension extensors are located posteriorly and flexor flexors are located in front of the joint. Only in the ankle and knee joint are they attached in the reverse order.

There are also abductors, located outside the joint and abducting one or another part of the body, and adductors, located inside and, conversely, adducting. They rotate muscles that lie transversely or obliquely relative to the vertical (instep supports outward, pronators inward).

Each movement is performed by a separate muscle group. Those of them that move in the same direction are synergists, on the contrary, they are antagonists. All groups work in harmony, contracting and relaxing at the right moments.

Each muscle type is triggered by nerve signals traveling at a speed of two dozen impulses per second. Each of them has its own number of nerve endings. For example, there are a lot of them in the eyes, but few in the thigh. The connections between the cerebral cortex and muscle groups are also uneven. The size of the zones does not depend on the mass of the recipient tissue, but on the complexity and subtlety of the resulting movements.

Each muscle receives brain impulses through some nerves, and nutritional regulation through others.

All this is coordinated with the regulation of its blood supply. The finest control of muscle activity is carried out by adjusting the tension it develops. In this case, either the number of fibers working in the muscle or the frequency of those approaching them changes. nerve impulses. As a result, the smoothness and consistency of all cuts is ensured.

The structure of the human shoulder

There are two types of muscles in this group:

• actually, the shoulder muscles, running from the deltoid to the elbow;
• muscles of the forearm, starting from the elbow and including all the muscles to the edge of the fingers.

The flexors used by humans are located in the front and include the muscles:

• biceps;
• coracobrachial;
• shoulder;

The extensors are located posteriorly and include:

• elbow;
• triceps

Arm flexors

The arm flexors are divided into zones. They answer:

• shoulder - behind the forearm;
• biceps – behind the shoulder and elbow joints, rotations and turns;
• coracobrachial - for flexion and rotation in the same joints.

The flexors of the hand are located lower.

Arm extensors

The arm extensors include the triceps, also called the triceps brachii muscles and consisting of the heads:

• lateral;
• medial;
• long.

The triceps, extending the arms at the elbow and shoulder, and forearm, also bring them to the body. The elbow muscles help him extend the limb at the elbow. All flexors and extensors of the arm work synchronously.

Muscles and their functions

The functionality of muscle groups is very diverse - especially in the hands that we actively work with. The shoulder joint works due to the muscles that extend to the shoulder from the bones of the shoulder girdle. The accuracy of finger movements is ensured by the extensor and flexor muscles of the wrist, as well as the metacarpus and forearm. They are connected to the bones by tendons.

The muscles in the legs are larger and stronger, which makes sense since they bear the most weight. The calf muscles are the most developed. It is located on the back of the shin and works when running and walking:

• bends at the knee;
• raises the heel;
• turns his foot.

The muscles of the buttocks are attached to the bones of the thigh and pelvis and attach hip joint, helping a person maintain a vertical position. This, as well as many other functions, is performed by the muscles of the back. It runs along the spine and is attached to processes that are directed backwards. They also provide backward bending of the body.

The muscle mass that runs from the skull to the bones of the body holds up the head. The pectoral muscles help with breathing and movement. Among the many functions of the abdominal muscles are bending and turning the torso in all directions.

The head has muscles for facial expression and chewing. The first group is extremely developed in humans and is responsible for the expression of emotions. The second group controls jaw movements.

The structure of the muscles of the forearm

The muscles in the forearm are divided into posterior and anterior. Each group has layers on the surface and in depth.

Front group

The main muscle group, including the flexors and extensors located in the front, includes several muscles. The flexor carpi ulnaris works in the wrist and elbow. Its radial counterpart works similarly, also penetrating the forearm. The pronator teres is smaller than the previous two, but repeats their functions.

The flexor digitorum superficialis helps flex the elbow, hand and phalanges in the middle. In the palm, the longus muscle controls this part of the arm and also helps it bend at the elbow.

The deep layer includes:

• on thumb, bending it, as well as the phalanx of the nail;
• deep digital flexor, working with the extreme phalanges and the hand;
• pronator quadratus – for the forearm.

Back group

In the posterior group, the superficial layer includes:

• wrist extensors (longus, brevis and ulnaris);
• digital extensors;
• brachioradialis muscle.

The latter works in the elbow and forearm.

The deep layer includes:

• extensors, short and;
• abductor longus muscle;
• extensor index finger;

The hand includes not only the extensor and flexor of the wrist, but also the muscles that work with the fingers:

• diverting;
• opposing;
• moving;
• bending;
• extensors.

At the same time, the arms move due to a huge number of muscles that make up a complex complex (and not just flexors and extensors).