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Inflammation forearm extensor muscle

Image : “Inflammation of a forearm extensor muscle” by scientificanimations.com. License: CC BY-SA 4.0


Flexors of the Elbow

The flexors of the elbow include the brachialis, the brachioradialis, and the biceps brachii.

Muscle Origin Insertion Nerve supply Function
Brachioradialis Proximal 2/3rds of lateral supracondylar ridge Lateral surface of distal radius and pre-styloid process Radial nerve (C6) Weak flexion of the elbow, and strong flexion when forearm mid-pronated
Brachialis Anterior aspect of the humerus lateral to the deltoid tuberosity Ulnar tuberosity Musculocutaneous nerve (C5-C7) Flexion of the elbow and assistance with supination
Biceps brachii Short head – coracoid process

Long head – supraglenoid tubercle

Tuberosity of the radius Musculocutaneous nerve (C5-C6) Supination of the forearm and assistance with elbow flexion
Extensor carpi radialis longus Lateral supracondylar ridge Dorsal aspect of the 2ndmetacarpal Radial nerve (C6, C7) Extension and abduction of wrist
Extensor carpi radialis brevis Lateral epicondyle (common extensor origin) Dorsal aspect of the 3rd metacarpal Deep branch of the radial nerve (C7)

Extensors of the Elbow

Triceps brachii Long head – infraglenoid tubercle

Lateral and medial heads – posterior humerus

Olecranon Radial nerve (C6 – C8) Extends the elbow

Flexors of the Arm

The flexors of the arm are divided into two groups: the common flexors and the deep flexors.

Common flexors

Muscle Origin Insertion Nerve supply Function
Pronator teres Ulnar head: coronoid process of ulna

Humeral head: medial epicondyle

Middle of the lateral surface of radius Median nerve (C7) Pronation and flexion of the forearm
Flexor carpi radialis Medial epicondyle of humerus Base of the 2ndmetacarpal Flexion and abduction of hand at the wrist
Palmaris longus Flexor retinaculum and palmar aponeurosis Flexion at the wrist and tension of palmar aponeurosis
Flexor carpi ulnaris Olecranon and posterior ulna Pisiform, hook of hamate, 5th metacarpal Ulnar nerve (C8) Flexion and adduction of hand at the wrist

Deep flexors

Muscle Origin Insertion Nerve supply Function
Flexor digitorum profundus Proximal surfaces of medial and anterior surfaces of the ulna and interosseous membrane Medial 4 digits distal phalanges Lateral muscle bellies to digits 2 and 3: Median nerve (C7, C8, T1)

Medial muscle bellies to digits 4 and 5: Ulnar nerve (T1)

Flexion of hand at wrist joint;

flexion of the distal interphalangeal joint

Flexor pollicis longus Anterior surface of radius and interosseous membrane Distal phalanx of first digits Anterior interosseous nerve (branch of median) (C8) Flexion of wrist;

flexion of interphalangeal and metacarpophalangeal joints of first digits

Pronator quadratus Distal quarter of the ulna Distal quarter of the radius Pronation of forearm

Extensors of the Arm

The extensors of the arm are also divided into two groups: the common extensors and the deep extensors.

Muscles That Move the Forearm

Image: “Muscles that move the forearm” by Phil Schatz. License: CC BY 4.0

Common extensors

Muscle Origin Insertion Nerve supply Function
Extensor carpi radialis (longus and brevis)
Extensor digitorum Lateral epicondyle (common extensor origin) Extensor expansion of medial 4 digits Posterior interosseous nerve (C7; from the deep radial nerve) Extension of wrist;

extension of medial four digits at metacarpophalangeal and interphalangeal joints (fifth digit for EDM

Extensor digiti minimi Extensor expansion of the 5th digit
Extensor carpi ulnaris Lateral epicondyle and posterior surface of ulna Dorsal aspect of the 5th metacarpal Extension and adduction of wrist

Deep extensors

Muscles Origin Insertion Nerve supply Function
Supinator Lateral epicondyle of humerus, supinator fossa and proximal ulna Posterior, lateral and anterior surfaces of proximal radius Deep branch of radial nerve (C8) Supination of forearm
Abductor pollicis longus Posterior surface of radius and ulna and interosseous membrane Metacarpal of the first digit Posterior interosseous nerve (C7 and C8) from deep radial nerve Extension of wrist; abduction of thumb and extension at carpometacarpal joint
Extensor pollicis longus Posterior surface of ulna and interosseous membrane Dorsal surface of distal phalanx of the first digit Extension of wrist;

extension of distal (EPL)/proximal (EPB) phalanx of thumb at interphalangeal joint;

extension of metacarpophalangeal and carpometacarpal joints

Extensor pollicis brevis Posterior surface of radius and interosseous membrane Dorsal surface of proximal phalanx of the first digit
Extensor indicis Posterior surface of the ulna Extensor expansion of 2nd finger Posterior interosseous nerve (C7 and C8) from deep radial nerve Extension of 2nd finger, and hand extension
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