The muscles of the forearm

The anterior group

The superficial layer

Pronator teres (m. pronator teres/круглый пронатор)

• Origin. From the common flexor origin on the medial epicondyle of the humerus.

• Insertion. The lateral surface of the shaft of the radius.

• Action. Pronation of the forearm.

• Nerve supply. Median nerve.

Flexor carpi radialis (m. flexor carpi radialis/лучевой сгибатель запястья)

• Origin. From the common flexor origin.

• Insertion. The base of metacarpals 2 and 3.

• Actions. Flexion and abduction of wrist.

• Nerve supply. Median nerve.

Palmaris longus (m. palmaris longus/длинная ладонная мышца)

• Origin. From the common flexor origin.

• Insertion. The flexor retinaculum and the palmar aponeurosis.

• Action. Flexor of the wrist (muscle оften absent).

• Nerve supply. Median nerve.

Flexor carpi ulnaris (m. flexor carpi ulnaris/локтевой сгибатель запястья)

• Origin. From the common flexor origin and the posterior border of the ulna.

• Insertion. To the pisiform and thence by the pisometacarpal ligament to the 5^th metacarpal.

• Actions. Flexion and adduction of the wrist.

• Nerve supply. Ulnar nerve.

The deep layers

Flexor digitorum superficial (m. flexor digitorum superficiallis/поверхностный сгибатель пальцев)

• Origin. From the common flexor origin and the shaft of the radius.

• Insertion. To the sides of the middle phalanges of the four fingers. The tendons are perforated by the tendons of flexor digitorum profundus.

• Actions. Flexion of the proximal two phalanges and of the wrist.

• Nerve supply. Median nerve.

Flexor pollicis longus (m. flexor pollicis longus/длинный сгибатель большого пальца кисти)

• Origin. From the front of the shaft of the radius.

• Insertion. To the distal phalanx of the thumb.

• Actions. Flexion of all the joints of the thumb.

• Nerve supply. Median nerve.

Flexor digitorum profundus (m. flexor digitorum profundus/глубокий сгибатель пальцев)

• Origin. From the front of the shaft of the ulna and its posterior border.

• Insertion. To the distal phalanges of the four fingers, the tendons pass­ing through those of flexor digitorum superficialis.

• Actions. Flexion of the fingers and the wrist.

• Nerve supply. Half by the median nerve and half by the ulnar nerve.

Pronator quadratus (m. pronator quadratus/квадратный пронатор)

• Origin. From the lower end of the front of the radius.

• Insertion. To the lower end of the ulna.

• Action. Pronator of the forearm.

• Nerve supply. Median nerve.

The posterior group

The superficial layer

Brachioradialis (m. brachioradialis/плечелучевая мышца)

• Origin. The lateral supracondylar ridge of the humerus.

• Insertion. The lower end of the radius.

• Action. Flexion of the elbow.

• Nerve supply. Radial nerve.

Extensor carpi radialis longus and brevis (mm. extensor carpi radialis longus et brevis/длинный и короткий лучевые разгибатели запястья)

• Origin. From the lateral supracondylar ridge of the humerus.

• Insertion. To the bases of the 2^nd and 3^rd metacarpals.

• Actions. Extension and abduction of the wrist.

• Nerve supply. Radial nerve.

Extensor digitorum (m. extensor digitorum/разгибатель пальцев)

• Origin. From the common extensor origin on the lateral epicondyle of the humerus.

• Insertion. To the bases of the middle and distal phalanges of the four fingers via the extensor expansion.

• Actions. Extension of the fingers and of the wrist (but see also the lumbricals and inlerossei).

• Nerve supply. Radial (posterior interosseous) nerve.

Extensor digiti minimi (m. extensor digiti minimi/разгибатель мизинца)

• Origin. From the common extensor origin.

• Insertion. To the extensor expansion of the little finger.

• Action. Extension of the little finger.

• Nerve supply. Radial (posterior interosseous) nerve.

Extensor carpi ulnaris (m. extensor carpi ulnaris/локтевой разгибатель запястья)

• Origin. From the common extensor origin and from the posterior bor­der of the ulna.

• Insertion. To the base of the 5^th metacarpal.

• Actions. Extension and adduction of the wrist.

• Nerve supply. Radial (posterior interosseous) nerve.

The deep layer

Supinator (m. supinator/супинатор)

• Origin. From the lateral side of the humerus and the ulna.

• Insertion. It wraps around the radius from behind to be inserted into the upper part of its shaft.

• Action. Supination.

• Nerve supply. Radial (posterior interosseous) nerve.

Abductor pollicis longus (m. abductor pollicis longus/длинная мышца, отводящая большой палец кисти)

• Origin. From the posterior surfaces of the radius and ulna.

• Insertion. To the base of the 1^st metacarpal.

• Actions. Abduction and extension of the thumb.

• Nerve supply. Radial (posterior interosseous) nerve.

Extensor pollicis brevis (m. extensor pollicis brevis/короткий разгибатель большого пальца кисти)

• Origin. From the back of the radius.

• Insertion. To the base of the proximal phalanx of the thumb.

• Action. Extension of the proximal phalanx of the thumb.

• Nerve supply. Radial (posterior interosseous) nerve.

Extensor pollicis longus (m. extensor pollicis longus/длинный разгибатель большого пальца кисти)

• Origin. From the back of the ulna.

• Insertion. Into the base of the distal phalanx of the thumb.

• Actions. Extension of all the joints of the thumb.

• Nerve supply. Radial (posterior interosseous) nerve.

Extensor indicis (m. extensor indicis/разгибатель указательного пальца)

• Origin. From the back of the ulna.

• Insertion. To the side of the extensor digitorum tendon to the index finger.

• Action. Helps to extend the index finger.

• Nerve supply. Radial (posterior interosseous) nerve.