The muscles of the forearm

Forearm muscles are divided into front and rear groups, each of which produce superficial and deep layers.

The front group

The surface layer

Round pronator (m. pronator teres) proniruet forearm (rotates it forward and inward so that the palm is rotated backward (down), and the thumb - into the median plane of the body) and participates in its bending. Thick and short arm consisting of two heads. A large, upper arm, head (caput humerale) from the medial epicondyle begins the humerus and the medial intermuscular septum brachial fascia, and a small, elbow, head (caput ulnare) starting from coronoid process of ulna tuberosity. Both heads combine to form a flattened abdomen. The place of attachment serves the middle third of the radius.

Brachioradialis muscle (m. brachioradialis), flexes the forearm and is involved in both pronation and supination of the forearm (rotates it so that the palm rotated anteriorly (upward), and the thumb - outwards from the median plane of the body) radius. Muscle has spindle-shaped, starting from the lateral humeral epicondyle and over the lateral intermuscular septum brachial fascia, and is attached at the lower end of the body radius.

Radial flexor wrist (m. flexor carpi radialis) flex and partially proniruet brush. Long, flat, dvuperistaya muscle, which is covered proximal part of the bicipital aponeurosis. Point of beginning is located on the medial epicondyle of the humerus and the fascia of the forearm, and the mounting position - based on the palmar surface of metacarpal II.

Long palmar muscle (m. palmaris longus) tightens palmar aponeurosis and is involved in bending the brush.

A characteristic feature of the structure of the muscles are short spindle-shaped abdomen and a long tendon. It begins at the medial epicondyle of the humerus and the fascia of the forearm inwards from radial flexor of wrist, and attached to the palmar aponeurosis (aponeurosis palmaris).

The elbow flexor wrist (m. flexor capiti ulnaris) flexes wrist and is involved in its enforcement. Characterized by long-bellied, thick tendon, and two heads. Humeral head start point is the medial epicondyle humerus and the fascia of the forearm, and ulnar head - elbow and upper arm of two-thirds of the ulna. Both heads are attached to the pisiform bone, part of the beam is attached to the hook-and V metacarpal bones.

Superficial finger flexor (m. flexor digitorum superficialis) flex the middle phalanx II-V fingers. This broad beam muscle is covered wrist flexor and palmar muscle long and is composed of two heads. Humeroulnar head (caput humeroulnare) from the medial epicondyle begins the humerus and ulna, radial head (caput radiale) - from the proximal ulna. Heads form a single abdomen with four tendons which pass on each hand and two legs attached to the base of middle phalanges II-V fingers.

The deep layer

The long flexor of the thumb brush (m. flexor pollicis longus) flexes the distal phalanx I (big) toe. Long, flat, semipenniform muscle, start point is the upper two-thirds of the anterior surface of ulna, interosseous membrane (membrana interossea) between the radius and ulna and medial epicondyle partially humerus. Attached at the base of the distal phalanx of the thumb.

The deep flexors (m. flexor digitorum profundus), doubles up all brush and distal phalanges II-V fingers. Characterized by a strongly developed and wide flat belly, the start point is located on the upper two-thirds of the anterior surface of ulna and interosseous membrane. Place attachment is based on the distal phalanges of fingers II-V.

The square pronator (m. pronator quadratus) rotates the forearm inwards (proniruet). The muscle is a thin rectangular plate, located in the area of the distal ends of the forearm bones. It begins at the medial edge of the body ulnar wrist and attached to the lateral edge and the front surface of the radius.

Posterior group

The surface layer

Long radial extensor carpal (m. extensor carpi radialis longus) Flexes the forearm at the elbow, wrist unbend and takes part in her abduction. Muscle has spindle-shaped and has a narrow tendon, greatly exceeding the length of the abdomen. The upper part of the muscle is covered brachioradialis muscle. Its start point is located at the lateral epicondyle of the humerus and lateral intermuscular septum brachial fascia, and the mounting position - on the back surface of the base of the metacarpal bone II.

Short radial extensor carpal (m. extensor carpi radialis brevis) Unbend the brush slightly averting her. This muscle is covered with slightly longer radial extensors of the wrist, starts from the lateral epicondyle of the humerus and the fascia of the forearm and attached to the back surface of the base of the metacarpal bone III.

In Fig. 115.
Upper arm and shoulder front view
1 - the biceps;
2 - shoulder muscles;
3 - biceps tendon;
4 - bicipital aponeurosis;
5 - round pronator;
6 - brachioradialis muscle;
7 - radial flexor wrist;
8 - elbow flexor wrist;
9 - long palmar muscle;
10 - superficial flexor of fingers;
11 - the long flexor of the thumb brush;
12 - short palmar muscle;
13 - palmar aponeurosis
In Fig. 116.
Forearm muscles, front view
1 - shoulder muscles;
2 - supinator;
3 - biceps tendon;
4 - long radial extensor wrist;
5 - deep flexor of fingers;
6 - brachioradialis muscle;
7 - long flexor of the thumb brush;
8 - round pronator;
9 - elbow flexor wrist;
10 - square pronator;
11 - muscle, opposing thumb;
12 - a muscle that causes the little finger;
13 - short flexor of the thumb brush;
14 - flexor tendon deep fingers;
15 - long flexor tendon of the thumb brush;
16 - superficial flexor tendon of finger
In Fig. 117.
Forearm muscles, front view
1 - round pronator;
2 - biceps tendon;
3 - supinator;
4 - the interosseous membrane;
5 - square pronator
In Fig. 118.
Forearm muscles, rear view
1 - brachioradialis muscle;
2 - triceps brachii;
3 - long radial extensor wrist;
4 - anconeus;
5 - elbow flexor wrist;
6 - extensor digitorum;
7 - ulnar extensor wrist;
8 - the little finger extensor;
9 - Long muscle abductor thumb;
10 - short extensor of the thumb brush;
11 - extensor retinaculum;
12 - long extensor of the thumb brush;
13 - extensor tendons of fingers
In Fig. 119.
Forearm muscles, rear view
1 - supinator;
2 - deep flexor of fingers;
3 - longest muscle abductor thumb;
4 - the long extensor of the thumb brush;
5 - short extensor of the thumb brush;
6 - the index finger extensor;
7 - extensor retinaculum;
8 - extensor digitorum tendon

Extensor digitorum (m. extensor digitorum) Unbend the fingers and is involved in straightening brush. Belly has a spindle-shaped, the direction of beams characterized dvuperistoy form. Its start point is located on a lateral epicondyle of the humerus and the fascia of the forearm. In the middle of its length goes belly into four tendons, which are on the back of the hand moving in tendon stretching, and those of its middle portion attached to the base of middle phalanx, and the side parts - the base of the distal phalanges of fingers II-V.

Pinky extensor (m. extensor digiti minimi) unbend the little finger. A small spindle-shaped muscle that begins at the lateral epicondyle of the humerus and attaches to the base of distal phalanx of the V finger (pinky).

Ulnar extensor carpal (m. extensor capiti ulnaris) Unbend brush and puts it into the ulnar side. The muscle has a long spindle-shaped abdomen, lateral epicondyle begins on the humerus and the fascia of the forearm and attached to the bottom of the rear surface of V metacarpal bone.

The deep layer

Supinator (m. supinator) Rotates the forearm outward (supiniruet) and is involved in straightening arms at the elbow. The muscle is shaped like a thin diamond plate. Its start point is located on the crest of the ulna arch support, lateral epicondyle of the humerus and elbow joint capsule. Place attachment is located on the lateral arch support, front and back of the upper third of the radius.

The long arm, thumb abductor (m. abductor pollicis longus), brings the thumb and is involved in playing a hand. The muscle is partially concealed by extensor digitorum and extensor short radial wrist, has a flat dvuperistoe abdomen, breaking into a long thin tendon. It starts at the back of the ulna and radial bones and is attached to the bottom of the I metacarpal bone.

Short extensor of the thumb brush (m. extensor pollicis brevis) removes the thumb and unbend his proximal phalanx. Starting point of this muscle is located on the back of the neck radius and interosseous membrane attachment site - on the basis of the proximal phalanx of the thumb and I pyastnofalangovogo capsule of the joint.

The long extensor of the thumb brush (m. extensor pollicis longus), unbend your thumb, partly leading him. The muscle is fusiform belly and long tendon. Starting point is on the back surface of the body of ulna and interosseous membrane attachment site - on the basis of the distal phalanx of the thumb.

The index finger extensor (m. extensor indicis), unbend his index finger. This muscle is sometimes absent. It is covered extensor digitorum, has a narrow, long, spindle-shaped abdomen. It starts at the back of the body of ulna and interosseous membrane, and attached to the back surface of the middle and distal phalanges of the index finger.





List of Abbreviations

a., aa. — arteria, arteriae (artery, the artery)

lig., ligg. — ligamentum, ligamenta (ligament, the ligaments)

m., mm. — musculus, musculi (muscle, the muscle)

n., nn. — nervus, nervi (nerve, the nerve)

r., rr. — ramus, rami (branch)

s. — seu (or)

v., vv. — vena, venae (vienna)