OIA - Arm Muscles

Biceps brachii — Origin, Insertion, Action?

O: Long head—supraglenoid tubercle; short head—coracoid process | I: Radial tuberosity + bicipital aponeurosis | A: Elbow flexion, forearm supination, assists shoulder flexion

Brachialis — Origin, Insertion, Action?

O: Distal half of anterior humerus | I: Ulnar tuberosity + coronoid process | A: Elbow flexion

Coracobrachialis — Origin, Insertion, Action?

O: Coracoid process | I: Middle third of medial humerus | A: Shoulder flexion + adduction

Triceps brachii — Origin, Insertion, Action?

O: Long— infraglenoid tubercle; lateral—posterior humerus above radial groove; medial—posterior humerus below radial groove | I: Olecranon process of ulna | A: Elbow extension; long head assists shoulder extension + adduction

Anconeus — Origin, Insertion, Action?

O: Lateral epicondyle of humerus | I: Proximal ulna/olecranon | A: Elbow extension + stabilization

Pronator teres — Origin, Insertion, Action?

O: Medial epicondyle + coronoid process | I: Lateral radius | A: Forearm pronation + assists elbow flexion

Flexor carpi radialis — Origin, Insertion, Action?

O: Medial epicondyle | I: Base of 2nd metacarpal | A: Wrist flexion + abduction

Palmaris longus — Origin, Insertion, Action?

O: Medial epicondyle | I: Palmar aponeurosis | A: Wrist flexion

Flexor carpi ulnaris — Origin, Insertion, Action?

O: Medial epicondyle + olecranon/posterior ulna | I: Pisiform, hook of hamate + base of 5th metacarpal | A: Wrist flexion + adduction

Flexor digitorum superficialis — Origin, Insertion, Action?

O: Medial epicondyle, coronoid process + anterior radius | I: Middle phalanges of digits 2–5 | A: Flexes PIP joints; assists MCP + wrist flexion

Flexor digitorum profundus — Origin, Insertion, Action?

O: Proximal ¾ anterior/medial ulna + interosseous membrane | I: Bases of distal phalanges digits 2–5 | A: Flexes DIP joints; assists wrist flexion

Flexor pollicis longus — Origin, Insertion, Action?

O: Anterior radius + interosseous membrane | I: Base of distal phalanx of thumb | A: Thumb flexion

Brachioradialis — Origin, Insertion, Action?

O: Proximal ⅔ lateral supracondylar ridge | I: Distal radius near styloid | A: Elbow flexion; returns forearm to neutral

Extensor carpi radialis longus — Origin, Insertion, Action?

O: Lateral supracondylar ridge | I: Base of 2nd metacarpal | A: Wrist extension + abduction

Extensor carpi radialis brevis — Origin, Insertion, Action?

O: Lateral epicondyle | I: Base of 3rd metacarpal | A: Wrist extension + abduction

Extensor digitorum — Origin, Insertion, Action?

O: Lateral epicondyle | I: Extensor expansions of digits 2–5 | A: Extends digits 2–5; assists wrist extension

Extensor carpi ulnaris — Origin, Insertion, Action?

O: Lateral epicondyle + posterior ulna | I: Base of 5th metacarpal | A: Wrist extension + adduction

Supinator — Origin, Insertion, Action?

O: Lateral epicondyle, radial collateral ligament, annular ligament + supinator crest of ulna | I: Proximal third of radius | A: Forearm supination

Abductor pollicis longus — Origin, Insertion, Action?

O: Posterior ulna, posterior radius + interosseous membrane | I: Base of 1st metacarpal | A: Thumb abduction

Extensor pollicis brevis — Origin, Insertion, Action?

O: Posterior radius + interosseous membrane | I: Base of proximal phalanx of thumb | A: Thumb extension

Extensor pollicis longus — Origin, Insertion, Action?

O: Posterior ulna + interosseous membrane | I: Base of distal phalanx of thumb | A: Thumb extension

Extensor indicis — Origin, Insertion, Action?

O: Posterior distal ulna + interosseous membrane | I: Extensor expansion of index finger | A: Index finger extension