Forearm and hand        
 Muscle Origin  Insertion  Action  Notes 
Extensor digitorum Common extensor tendon from lateral epicondyle of humerus Dorsal surface of middle and distal phalanges 2-5 
( four fingers)
Extends four fingers, assists in extension of the wrist  
Pronator quadratus        
Palmaris longus Medial epicondyle of humerus Palmar aponeurosis Flexion of hand and wrist Flex wrist against resistance to find tendon.

May be absent in one or both sides in some people.

Flexor digitorum superficialis Medial epicondyle of humerus, coronoid process of ulna, proximal radius Four tendons into the middle phalanges of fingers 2-5, palmar surface Flexes the middle and proximal phalanges of fingers 2-5, flexion of the wrist and forearm. Median nerve and ulnar artery are under origin
Flexor carpi radialis Medial epicondyle of humerus Base of 2nd to base of 3rd metacarpal bone Flexes and abducts the wrist, pronation of the forearm and flexion of the elbow  
Flexor carpi ulnaris Medial epicondyle of humerus, medial olecranon and proximal posterior ulna Pisiform bone  Flexes and adducts the wrist and flexes the elbow  
Extensor carpi radialis longus Lateral supracondylar ridge of humerus Base of 2nd metacarpal bone dorsal side Extends and abducts the wrist, flexes the elbow  
Extensor carpi radialis brevis Lateral epicondyle of humerus Dorsal surface of base of 3rd metacarpal bone Extends and assists in abduction of the wrist  
Extensor carpi ulnaris Lateral epicondyle of humerus, posterior border of ulna Base of 5th metacarpal bone, ulnar side Extends and adducts the wrist Tendon runs through a groove between the head of the ulna and the styloid process of ulna
Flexor digitorum profundus Anterior and medial surfaces of proximal ¾ of ulna Four tendons into bases of distal phalanges on anterior surface Flexes distal interphalangeal joints of four fingers, flexes proximal interphalageal and metacarpopphalangeal joints  
Flexor pollicus longus Anterior surface of radius, deep to flexors Distal phalange of thumb Flexes thumb  
Supinator Lateral epicondyle of humerus, posterior ulna Proximal anterior shaft of humerus Supinates forearm  
Extensor pollicus longus and brevis Posterior surface of radius and ulna, deep to extensors Brevis –proximal phalange of thumb

Longus- distal phalange of thumb

Extends the thumb  
Opponens pollicis Palmar retinaculum, trapezium 1st metacarpal anterior surface Opposition of thumb to each digit.

Rotates 1st metacarpal so the thumbnail faces the ceiling when the hand is resting palm up.



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