Upper extremity muscles origin insertion nerve supply and muscle action
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I now have very comprehensive data from the THIEME Atlas. I have enough to compile a thorough, well-organized answer covering all upper extremity muscles. Let me now compile the complete reference:
Upper Extremity Muscles: Origin, Insertion, Nerve Supply & Action
Source: General Anatomy and Musculoskeletal System, THIEME Atlas of Anatomy
SHOULDER GIRDLE MUSCLES
Muscles That Migrated from the Head
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Trapezius | Descending part: nuchal ligament, spinous processes C1-C7; Transverse part: spinous processes T1-T4; Ascending part: spinous processes T5-T12 | Descending part: lateral third of clavicle; Transverse part: acromion; Ascending part: scapular spine | Accessory nerve (CN XI) + cervical plexus (C2, C4) | Descending: draws scapula obliquely upward, rotates glenoid cavity inferiorly, tilts/rotates head; Transverse: draws scapula medially; Ascending: draws scapula medially downward; Entire muscle: steadies scapula |
| Sternocleidomastoid | Sternal head: manubrium; Clavicular head: medial third of clavicle | Mastoid process and superior nuchal line | Accessory nerve (CN XI) + cervical plexus (C2, C3) | Unilateral: tilts head to same side, rotates to opposite side; Bilateral: extends head, assists respiration (head fixed) |
| Omohyoid | Superior border of scapula | Body of hyoid bone | Ansa cervicalis (C1-C3) | Depresses/fixes hyoid; moves larynx and hyoid downward; tenses cervical fascia |
Posterior Muscles of Trunk and Shoulder Girdle
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Levator scapulae | Transverse processes of C1-C4 | Medial border of scapula (above scapular spine) | Dorsal scapular nerve (C4, C5) | Elevates scapula; draws scapula medially upward; steadies scapula |
| Rhomboid minor | Spinous processes of C6-C7, lower nuchal ligament | Medial border of scapula (at level of scapular spine) | Dorsal scapular nerve (C4, C5) | Steadies scapula; draws scapula medially upward |
| Rhomboid major | Spinous processes of T1-T4 | Medial border of scapula (below scapular spine) | Dorsal scapular nerve (C4, C5) | Steadies scapula; draws scapula medially upward |
Anterior Muscles of Trunk and Shoulder Girdle
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Subclavius | First rib (junction of rib and costal cartilage) | Clavicle (inferior surface, middle third) | Nerve to subclavius (C5, C6) | Depresses clavicle; steadies sternoclavicular joint |
| Pectoralis minor | Third to fifth ribs (anterior surface) | Coracoid process of scapula | Medial pectoral nerve (C8, T1) | Tilts scapula anteriorly; draws scapula forward and downward; assists in raising ribs (respiration) |
| Serratus anterior | First to ninth ribs (lateral surface) | Costal surface of medial border of scapula | Long thoracic nerve (C5-C7) | Protracts (draws forward) scapula; rotates glenoid cavity upward (elevating arm); holds scapula against thorax |
MUSCLES OF THE SHOULDER JOINT
Rotator Cuff (SITS)
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Supraspinatus (S) | Supraspinous fossa of scapula | Greater tubercle of humerus (superior facet) | Suprascapular nerve (C4-C6) | Initiates/assists abduction of arm (first 15°); stabilizes glenohumeral joint |
| Infraspinatus (I) | Infraspinous fossa of scapula | Greater tubercle of humerus (middle facet) | Suprascapular nerve (C4-C6) | External (lateral) rotation of arm; stabilizes glenohumeral joint |
| Teres minor (T) | Lateral border of scapula | Greater tubercle of humerus (inferior facet) | Axillary nerve (C5, C6) | External rotation; weak adduction; stabilizes glenohumeral joint |
| Subscapularis (S) | Subscapular fossa of scapula | Lesser tubercle of humerus | Upper + lower subscapular nerves (C5, C6) | Internal (medial) rotation; stabilizes glenohumeral joint |
Other Shoulder Joint Muscles
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Deltoid | Clavicular part: lateral clavicle; Acromial part: acromion; Spinal part: scapular spine | Deltoid tuberosity of humerus | Axillary nerve (C5, C6) | Clavicular part: flexion, internal rotation; Acromial: abduction (15°-90°); Spinal: extension, external rotation; Entire: abduction |
| Teres major | Inferior angle of scapula (dorsal surface) | Crest of lesser tubercle of humerus | Lower subscapular nerve (C5-C7) | Adduction, internal rotation, extension of arm; assists latissimus dorsi |
| Latissimus dorsi | Spinous processes T7-L5, sacrum, iliac crest, lower 3-4 ribs | Intertubercular groove of humerus (floor) | Thoracodorsal nerve (C6-C8) | Extension, adduction, internal rotation; draws arm downward/backward |
| Pectoralis major | Clavicular part: medial half of clavicle; Sternocostal: sternum + ribs 2-6; Abdominal: rectus sheath | Crest of greater tubercle of humerus | Medial + lateral pectoral nerves (C5-T1) | Adduction, internal rotation, flexion (entire muscle); assists respiration |
| Coracobrachialis | Coracoid process of scapula | Humerus (medial surface, in line with lesser tubercle crest) | Musculocutaneous nerve (C5-C7) | Flexion, adduction, internal rotation |
MUSCLES OF THE ARM
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Biceps brachii | Long head: supraglenoid tubercle; Short head: coracoid process of scapula | Radial tuberosity and bicipital aponeurosis | Musculocutaneous nerve (C5, C6) | Elbow: flexion; Forearm: supination (most powerful supinator); Shoulder: weak flexion |
| Brachialis | Anterior humerus (distal half) | Ulnar tuberosity and coronoid process of ulna | Musculocutaneous nerve (C5, C6); small radial nerve branch | Elbow flexion (primary flexor regardless of forearm position) |
| Triceps brachii | Long head: infraglenoid tubercle of scapula; Lateral head: posterior humerus (above radial groove); Medial head: posterior humerus (below radial groove) | Olecranon process of ulna | Radial nerve (C6-C8) | Elbow extension; Long head: shoulder adduction/extension |
| Anconeus | Lateral epicondyle of humerus (posterior surface) | Lateral surface of olecranon and proximal ulna | Radial nerve (C7, C8) | Elbow extension; stabilizes/tenses elbow joint capsule |
MUSCLES OF THE FOREARM
Anterior (Flexor) Compartment - Superficial Layer
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Pronator teres | Humeral head: medial epicondyle; Ulnar head: coronoid process of ulna | Lateral surface of radius (middle third) | Median nerve (C6) | Forearm pronation; weak elbow flexion |
| Flexor carpi radialis | Medial epicondyle of humerus (common flexor origin) | Base of 2nd (and 3rd) metacarpal | Median nerve (C6, C7) | Wrist flexion + radial deviation; weak elbow flexion; weak forearm pronation |
| Palmaris longus | Medial epicondyle (common flexor origin) | Palmar aponeurosis and flexor retinaculum | Median nerve (C7, C8) | Wrist flexion; tenses palmar aponeurosis. Absent in ~14% of individuals |
| Flexor carpi ulnaris | Humeral head: medial epicondyle; Ulnar head: olecranon and posterior ulna | Pisiform, hamate, base of 5th metacarpal | Ulnar nerve (C7, C8) | Wrist flexion + ulnar deviation; weak elbow flexion |
| Flexor digitorum superficialis (FDS) | Humeral head: medial epicondyle; Ulnar head: coronoid process; Radial head: distal to radial tuberosity | Sides of middle phalanges of digits 2-5 (splits to allow FDP passage) | Median nerve (C7, C8, T1) | Flexion of PIP joints (digits 2-5); flexes MCP joints; weak wrist flexion |
Anterior (Flexor) Compartment - Deep Layer
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Flexor digitorum profundus (FDP) | Anterior + medial ulna (upper 3/4), interosseous membrane | Bases of distal phalanges of digits 2-5 | Medial half (digits 4,5): ulnar nerve (C8, T1); Lateral half (digits 2,3): anterior interosseous branch of median nerve (C8, T1) | Flexion of DIP joints; also flexes PIP, MCP, and wrist |
| Flexor pollicis longus | Anterior radius (middle 2/4), interosseous membrane | Base of distal phalanx of thumb | Anterior interosseous nerve (branch of median, C8, T1) | Flexion of IP joint of thumb; weak MCP flexion |
| Pronator quadratus | Anterior surface of distal ulna | Anterior surface of distal radius | Anterior interosseous nerve (C8, T1) | Forearm pronation (primary pronator) |
Posterior (Extensor) Compartment - Superficial Layer
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Brachioradialis | Lateral supracondylar ridge of humerus | Styloid process of radius | Radial nerve (C5, C6) | Elbow flexion (especially from mid-pronation); assists pro/supination to neutral |
| Extensor carpi radialis longus (ECRL) | Lateral supracondylar ridge (distal) | Base of 2nd metacarpal | Radial nerve (C6, C7) | Wrist extension + radial deviation; weak elbow flexion |
| Extensor carpi radialis brevis (ECRB) | Lateral epicondyle (common extensor origin) | Base of 3rd metacarpal | Deep branch of radial nerve / posterior interosseous nerve (C7, C8) | Wrist extension (+ slight radial deviation) |
| Extensor digitorum | Lateral epicondyle (common extensor origin) | Extensor expansion (dorsal hood) of digits 2-5 | Posterior interosseous nerve (C7, C8) | Extension of MCP, PIP, DIP joints of digits 2-5; weak wrist extension |
| Extensor digiti minimi | Lateral epicondyle (common extensor origin) | Extensor expansion of little finger (digit 5) | Posterior interosseous nerve (C7, C8) | Extension of MCP joint of little finger |
| Extensor carpi ulnaris (ECU) | Lateral epicondyle + posterior border of ulna | Base of 5th metacarpal | Posterior interosseous nerve (C7, C8) | Wrist extension + ulnar deviation |
Posterior (Extensor) Compartment - Deep Layer
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Supinator | Lateral epicondyle, radial collateral ligament, supinator crest of ulna | Lateral surface of proximal radius (anterior neck to tuberosity) | Deep branch of radial nerve (C6, C7) | Forearm supination (slow/unresisted; also acts without biceps when elbow extended) |
| Abductor pollicis longus (APL) | Posterior ulna and radius, interosseous membrane | Base of 1st metacarpal | Posterior interosseous nerve (C7, C8) | Abduction + extension of thumb at CMC joint; weak radial deviation of wrist |
| Extensor pollicis brevis (EPB) | Posterior radius, interosseous membrane | Base of proximal phalanx of thumb | Posterior interosseous nerve (C7, C8) | Extension of MCP joint of thumb; abduction of thumb |
| Extensor pollicis longus (EPL) | Posterior middle ulna, interosseous membrane | Base of distal phalanx of thumb | Posterior interosseous nerve (C7, C8) | Extension of IP + MCP joints of thumb; adduction/retropulsion of thumb |
| Extensor indicis | Posterior distal ulna, interosseous membrane | Extensor expansion of index finger (digit 2) | Posterior interosseous nerve (C7, C8) | Extension of MCP joint of index finger (independent of other fingers) |
INTRINSIC HAND MUSCLES
Thenar Muscles
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Abductor pollicis brevis | Flexor retinaculum, scaphoid, trapezium | Base of proximal phalanx of thumb (radial side) | Median nerve (C8, T1) | Abduction of thumb (CMC + MCP joints) |
| Flexor pollicis brevis | Superficial head: flexor retinaculum + trapezium; Deep head: trapezoid + capitate | Base of proximal phalanx of thumb | Superficial head: median nerve (C8, T1); Deep head: ulnar nerve (C8, T1) | Flexion of MCP joint of thumb |
| Opponens pollicis | Trapezium (tubercle), flexor retinaculum | Radial border of 1st metacarpal | Median nerve (C8, T1) | Opposition of thumb (CMC joint) |
| Adductor pollicis | Oblique head: capitate, bases of 2nd-3rd metacarpals; Transverse head: anterior surface of 3rd metacarpal shaft | Base of proximal phalanx of thumb (ulnar side) | Ulnar nerve (C8, T1) | Adduction of thumb; assists in opposition |
Hypothenar Muscles
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| Abductor digiti minimi | Pisiform and pisohamate ligament | Base of proximal phalanx of little finger (ulnar side) | Ulnar nerve (C8, T1) | Abduction of little finger |
| Flexor digiti minimi brevis | Hook of hamate, flexor retinaculum | Base of proximal phalanx of little finger | Ulnar nerve (C8, T1) | Flexion of MCP joint of little finger |
| Opponens digiti minimi | Hook of hamate, flexor retinaculum | Medial border of 5th metacarpal | Ulnar nerve (C8, T1) | Opposition of little finger (draws 5th metacarpal anteriorly) |
| Palmaris brevis | Flexor retinaculum, palmar aponeurosis | Skin of hypothenar eminence | Ulnar nerve (C8, T1) | Deepens hollow of palm; protects ulnar neurovascular bundle |
Lumbricals
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| 1st + 2nd Lumbricals | Radial aspect of FDP tendons (digits 2 and 3) | Radial side of extensor expansion (digits 2, 3) | Median nerve (C8, T1) | MCP joint flexion + IP joint extension of digits 2, 3 |
| 3rd + 4th Lumbricals | Adjacent sides of FDP tendons (digits 3-4 and 4-5) | Radial side of extensor expansion (digits 4, 5) | Ulnar nerve (C8, T1) | MCP joint flexion + IP joint extension of digits 4, 5 |
Interossei
| Muscle | Origin | Insertion | Nerve Supply | Action |
|---|---|---|---|---|
| 4 Dorsal interossei (DAB - Dorsal ABduct) | Adjacent sides of metacarpals (bipennate, from 2 metacarpals each) | Proximal phalanges + extensor expansion of digits 2-4 | Ulnar nerve (C8, T1) | Abduct digits 2-4 away from middle finger; flex MCP + extend IP joints |
| 3 Palmar interossei (PAD - Palmar ADduct) | Medial side of 2nd metacarpal; lateral sides of 4th and 5th metacarpals (unipennate) | Proximal phalanges + extensor expansion of digits 2, 4, 5 | Ulnar nerve (C8, T1) | Adduct digits 2, 4, 5 toward middle finger; flex MCP + extend IP joints |
QUICK REFERENCE: NERVE SUPPLY SUMMARY
| Nerve | Key Muscles |
|---|---|
| Axillary (C5, C6) | Deltoid, teres minor |
| Musculocutaneous (C5-C7) | Biceps brachii, brachialis, coracobrachialis |
| Radial (C5-C8) | Triceps, anconeus, brachioradialis, ECRL; via posterior interosseous nerve: ECRB, extensor digitorum, EDM, ECU, supinator, APL, EPB, EPL, extensor indicis |
| Median (C6-T1) | Pronator teres, FCR, palmaris longus, FDS, FPL, pronator quadratus, FDP (lateral half); thenar muscles (APB, opponens pollicis, FPB superficial head), 1st + 2nd lumbricals |
| Ulnar (C7-T1) | FCU, FDP (medial half), all hypothenar muscles, adductor pollicis, FPB deep head, all interossei, 3rd + 4th lumbricals, palmaris brevis |
| Suprascapular (C4-C6) | Supraspinatus, infraspinatus |
| Dorsal scapular (C4, C5) | Levator scapulae, rhomboids |
| Long thoracic (C5-C7) | Serratus anterior |
| Thoracodorsal (C6-C8) | Latissimus dorsi |
| Subscapular nerves (C5, C6) | Subscapularis, teres major |
| Pectoral nerves (C5-T1) | Pectoralis major, pectoralis minor |
| Accessory (CN XI) | Trapezius, sternocleidomastoid |
KEY CLINICAL MNEMONICS
- Rotator cuff = SITS: Supraspinatus, Infraspinatus, Teres minor, Subscapularis
- Radial nerve = ALL extensors (posterior compartment arm + forearm)
- "LOAF" = Median nerve intrinsics: Lumbricals 1&2, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis
- Ulnar nerve = most intrinsics (all interossei, hypothenar, adductor pollicis, 3rd + 4th lumbricals)
- Dorsal interossei DAB (Dorsal ABduct); Palmar interossei PAD (Palmar ADduct)
- "The only intrinsic muscles NOT supplied by ulnar nerve": LOAF (median nerve)
- "PIN" = Posterior Interosseous Nerve: deep branch of radial - supplies all deep extensors of forearm
Source: General Anatomy and Musculoskeletal System, THIEME Atlas of Anatomy; innervation table confirmed across all upper limb sections.
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