Upper limb origins, insertions, innervations + actions

Trapezius — upper fibres

O: medial occipital bone and ligamentum nuchae. I: lateral clavicle. N: spinal accessory nerve (CN XI), with C3–C4 proprioceptive fibres. A: elevates clavicle/scapula; assists scapular retraction and upward rotation.

Trapezius — middle fibres

O: C7–T1 spinous processes. I: acromion and spine of scapula. N: spinal accessory nerve (CN XI), C3–C4 proprioception. A: scapular retraction/adduction.

Trapezius — lower fibres

O: lower thoracic spinous processes. I: medial end/root of scapular spine. N: spinal accessory nerve (CN XI), C3–C4 proprioception. A: scapular depression, retraction and upward rotation.

Levator scapulae

O: transverse processes of C1–C4. I: dorsal medial border of scapula, superior to the spine. N: dorsal scapular nerve (C5) and C3–C4 ventral rami. A: scapular elevation, retraction and downward rotation.

Rhomboid minor

O: ligamentum nuchae and C7–T1 spinous processes. I: dorsal medial border of scapula at the root of its spine. N: dorsal scapular nerve (C5). A: scapular retraction, downward rotation and fixation against thoracic wall.

Rhomboid major

O: T2–T5 spinous processes. I: dorsal medial border of scapula below its spine. N: dorsal scapular nerve (C5). A: scapular retraction, downward rotation and fixation against thoracic wall.

Serratus anterior

O: anterolateral surfaces of ribs 1–9. I: ventral/anterior surface of medial border of scapula. N: long thoracic nerve (C5–C7). A: scapular protraction/abduction, upward rotation and holding scapula against thoracic wall.

Pectoralis minor

O: anterior ribs 3–5. I: coracoid process. N: medial pectoral nerve (C8–T1). A: anterior tilt and depression of scapula; stabilises scapula.

Subclavius

O: 1st rib and costal cartilage. I: inferior surface of middle third of clavicle. N: nerve to subclavius (C5–C6). A: depresses/stabilises clavicle and SC joint.

Pectoralis major — clavicular head

O: medial two-thirds of clavicle. I: lateral lip of intertubercular sulcus. N: medial and lateral pectoral nerves (C5–T1). A: GH flexion, medial rotation and horizontal flexion.

Pectoralis major — sternocostal head

O: sternum and costal cartilages 1–7. I: lateral lip of intertubercular sulcus. N: medial and lateral pectoral nerves (C5–T1). A: GH adduction, medial rotation and horizontal flexion; extends the arm from a flexed position.

Latissimus dorsi

O: T7–T12 spinous processes, thoracolumbar fascia, posterior iliac crest and lower 3–4 ribs. I: floor of intertubercular sulcus. N: thoracodorsal nerve (C6–C8). A: GH extension, adduction and medial rotation.

Deltoid

O: lateral clavicle (anterior), acromion (middle), spine of scapula (posterior). I: deltoid tuberosity. N: axillary nerve (C5–C6). A: anterior fibres flex, medially rotate and horizontally flex; middle fibres abduct; posterior fibres extend, laterally rotate, horizontally extend and adduct.

Supraspinatus

O: supraspinous fossa. I: superior facet of greater tubercle. N: suprascapular nerve (C5–C6). A: initiates/assists GH abduction; compresses and stabilises humeral head in glenoid.

Infraspinatus

O: infraspinous fossa. I: middle facet of greater tubercle. N: suprascapular nerve (C5–C6). A: GH lateral rotation; compresses humeral head and provides an inferior stabilising pull.

Teres minor

O: dorsal lateral border of scapula. I: inferior facet of greater tubercle. N: axillary nerve (C5–C6). A: GH lateral rotation; compresses/stabilises humeral head.

Subscapularis

O: subscapular fossa. I: lesser tubercle. N: upper and lower subscapular nerves (C5–C7). A: GH medial rotation; compresses/stabilises humeral head and provides an inferior stabilising pull.

Teres major

O: posterior scapula, just lateral to inferior angle. I: medial lip of intertubercular sulcus. N: lower subscapular nerve (C5–C7). A: GH medial rotation, adduction and extension.

Coracobrachialis

O: coracoid process. I: medial middle shaft of humerus. N: musculocutaneous nerve (C5–C7). A: GH flexion and adduction.

Biceps brachii — long head

O: supraglenoid tubercle and superior glenoid labrum. I: radial tuberosity and bicipital aponeurosis. N: musculocutaneous nerve (C5–C6). A: elbow flexion and forearm supination; assists GH flexion.

Biceps brachii — short head

O: coracoid process. I: radial tuberosity and bicipital aponeurosis. N: musculocutaneous nerve (C5–C6). A: elbow flexion and forearm supination; assists GH flexion.

Brachialis

O: distal half of anterior humerus. I: ulnar tuberosity and coronoid process. N: musculocutaneous nerve (C5–C6). A: primary elbow flexor.

Triceps brachii — long head

O: infraglenoid tubercle. I: olecranon process. N: radial nerve (C6–C8). A: elbow extension; assists GH extension and adduction.

Triceps brachii — lateral head

O: posterior humerus superior to radial groove. I: olecranon process. N: radial nerve (C6–C8). A: elbow extension.

Triceps brachii — medial head

O: posterior humerus inferior to radial groove. I: olecranon process. N: radial nerve (C6–C8). A: elbow extension.

Anconeus

O: lateral epicondyle of humerus. I: olecranon, posterior proximal ulna and elbow capsule. N: radial nerve (C6–C8). A: assists elbow extension, retracts capsule during extension, abducts ulna during pronation and supports posterolateral elbow stability.

Pronator teres

O: medial epicondyle and coronoid process of ulna. I: lateral midshaft of radius. N: median nerve (C6–C7). A: forearm pronation; weak elbow flexion.

Flexor carpi radialis

O: medial epicondyle. I: bases of 2nd and 3rd metacarpals. N: median nerve (C6–C7). A: wrist flexion and radial deviation/abduction.

Palmaris longus

O: medial epicondyle. I: flexor retinaculum and palmar aponeurosis. N: median nerve (C7–C8). A: tenses palmar aponeurosis; weak wrist flexion.

Flexor carpi ulnaris

O: medial epicondyle; olecranon and posterior proximal ulna. I: pisiform, hook of hamate and base of 5th metacarpal. N: ulnar nerve (C7–C8). A: wrist flexion and ulnar deviation/adduction.

Pronator quadratus

O: distal anterior ulna. I: distal anterior radius. N: anterior interosseous branch of median nerve (C7–C8). A: forearm pronation; stabilises distal radioulnar joint.

Flexor digitorum superficialis

O: medial epicondyle, coronoid process/proximal ulna and anterior radius. I: sides of middle phalanges of digits 2–5. N: median nerve (C8–T1). A: flexes PIP joints of digits 2–5; also assists MCP and wrist flexion.

Flexor digitorum profundus

O: anterior/medial ulna and interosseous membrane. I: bases of distal phalanges of digits 2–5. N: lateral half (digits 2–3): anterior interosseous median nerve; medial half (digits 4–5): ulnar nerve, C8–T1. A: flexes DIP joints; also assists MCP and wrist flexion.

Flexor pollicis longus

O: anterior radius and interosseous membrane. I: base of distal phalanx of thumb. N: anterior interosseous branch of median nerve (C7–C8). A: flexes thumb IP joint; assists thumb MCP flexion.

Brachioradialis

O: lateral supracondylar ridge. I: lateral distal radius, proximal to styloid process. N: radial nerve (C5–C6). A: elbow flexion; brings forearm back toward neutral from pronation or supination.

Extensor carpi radialis longus

O: lateral supracondylar ridge. I: dorsal base of 2nd metacarpal. N: radial nerve (C6–C7). A: wrist extension and radial deviation/abduction.

Extensor carpi radialis brevis

O: lateral epicondyle. I: dorsal base of 3rd metacarpal. N: deep branch of radial nerve (C7–C8). A: wrist extension and radial deviation/abduction.

Extensor carpi ulnaris

O: lateral epicondyle and posterior border of ulna. I: dorsal base of 5th metacarpal. N: posterior interosseous nerve (C7–C8). A: wrist extension and ulnar deviation/adduction.

Supinator

O: lateral epicondyle, radial collateral/annular ligaments and supinator crest of ulna. I: proximal radius. N: deep branch of radial nerve/posterior interosseous nerve (C6–C7). A: forearm supination.

Extensor digitorum

O: lateral epicondyle. I: extensor hoods of digits 2–5, continuing to middle/distal phalanges. N: posterior interosseous nerve (C7–C8). A: extends digits 2–5; assists wrist extension.

Extensor digiti minimi

O: lateral epicondyle. I: extensor hood of 5th digit. N: posterior interosseous nerve (C7–C8). A: extends little finger.

Abductor pollicis longus

O: posterior radius, ulna and interosseous membrane. I: base of 1st metacarpal. N: posterior interosseous nerve (C7–C8). A: abducts thumb at 1st CMC joint.

Extensor pollicis brevis

O: posterior radius and interosseous membrane. I: base of proximal phalanx of thumb. N: posterior interosseous nerve (C7–C8). A: extends thumb MCP joint; can assist CMC extension.

Extensor pollicis longus

O: posterior ulna and interosseous membrane. I: base of distal phalanx of thumb. N: posterior interosseous nerve (C7–C8). A: extends thumb IP joint; also assists MCP and CMC extension.

Extensor indicis

O: posterior distal ulna and interosseous membrane. I: extensor hood of index finger. N: posterior interosseous nerve (C7–C8). A: extends index finger.

Abductor pollicis brevis

O: flexor retinaculum, scaphoid and trapezium. I: base of proximal phalanx of thumb and extensor hood. N: recurrent branch of median nerve (C8–T1). A: abducts thumb at MCP; can assist thumb IP extension.

Flexor pollicis brevis

O: flexor retinaculum and trapezium. I: base of proximal phalanx of thumb. N: mainly recurrent branch of median nerve (C8–T1). A: flexes thumb MCP joint.

Opponens pollicis

O: flexor retinaculum and trapezium. I: lateral border of 1st metacarpal. N: recurrent branch of median nerve (C8–T1). A: opposition of thumb: flexes, abducts and medially rotates 1st metacarpal.

Abductor digiti minimi

O: pisiform, pisohamate ligament and FCU tendon. I: base of proximal phalanx of 5th digit. N: deep branch of ulnar nerve (C8–T1). A: abducts 5th digit at MCP.

Flexor digiti minimi brevis

O: flexor retinaculum and hook of hamate. I: base of proximal phalanx of 5th digit. N: deep branch of ulnar nerve (C8–T1). A: flexes 5th MCP joint.

Opponens digiti minimi

O: flexor retinaculum and hook of hamate. I: medial border of 5th metacarpal. N: deep branch of ulnar nerve (C8–T1). A: opposition/cupping of 5th metacarpal.

Adductor pollicis

O: oblique head—capitate and bases of 2nd–3rd metacarpals; transverse head—shaft of 3rd metacarpal. I: base of proximal phalanx and extensor hood of thumb. N: deep branch of ulnar nerve (C8–T1). A: adducts thumb; assists thumb IP extension through extensor hood.

Palmaris brevis

O: palmar aponeurosis and flexor retinaculum. I: skin/dermis on ulnar side of palm. N: superficial branch of ulnar nerve (C8–T1). A: wrinkles skin of palm and improves grip.

Palmar interossei (digits 2, 4 and 5)

O: palmar surfaces of metacarpals 2, 4 and 5. I: bases of proximal phalanges and extensor hoods of same digits. N: deep branch of ulnar nerve (C8–T1). A: adduct digits toward middle finger; assist MCP flexion and IP extension. PAD = palmar interossei ADduct.

Dorsal interossei (four muscles)

O: adjacent sides of metacarpals. I: bases of proximal phalanges and extensor hoods of digits 2–4. N: deep branch of ulnar nerve (C8–T1). A: abduct digits away from middle finger; assist MCP flexion and IP extension. DAB = dorsal interossei ABduct.

Lumbricals 1 and 2

O: lateral sides of FDP tendons to digits 2 and 3. I: radial side of extensor hoods of digits 2 and 3. N: median nerve (C8–T1). A: flex MCP joints and extend IP joints of digits 2–3.

Lumbricals 3 and 4

O: adjacent FDP tendons to digits 3–5. I: radial side of extensor hoods of digits 4 and 5. N: deep branch of ulnar nerve (C8–T1). A: flex MCP joints and extend IP joints of digits 4–5.

Rectus abdominis

O: pubic crest and pubic symphysis. I: xiphoid process and costal cartilages 5–7. N: thoracoabdominal nerves T6–T12. A: trunk flexion, posterior pelvic tilt and abdominal compression.

External oblique

O: external surfaces of ribs 5–12. I: linea alba, pubic tubercle and anterior iliac crest. N: thoracoabdominal nerves T7–T12. A: bilateral trunk flexion/compression; unilateral ipsilateral lateral flexion and contralateral rotation.

Internal oblique

O: thoracolumbar fascia, anterior iliac crest and lateral inguinal ligament. I: ribs 10–12, linea alba and pubis via conjoint tendon. N: thoracoabdominal nerves T6–T12 and L1. A: bilateral trunk flexion/compression; unilateral ipsilateral lateral flexion and ipsilateral rotation.

Iliocostalis

O: common erector-spinae tendon from posterior iliac crest, sacrum and lumbar spinous processes. I: angles of ribs and cervical transverse processes. N: dorsal rami of spinal nerves. A: bilateral spinal extension; unilateral ipsilateral lateral flexion.

Longissimus

O: common erector-spinae tendon and transverse processes. I: ribs, thoracic/cervical transverse processes and mastoid process (capitis part). N: dorsal rami of spinal nerves. A: bilateral spinal/head extension; unilateral ipsilateral lateral flexion; longissimus capitis also rotates head ipsilaterally.

Spinalis

O: lower thoracic/upper lumbar spinous processes. I: upper thoracic and cervical spinous processes. N: dorsal rami of spinal nerves. A: spinal extension.

Splenius capitis

O: lower ligamentum nuchae and spinous processes C7–T3/4. I: mastoid process and lateral superior nuchal line. N: dorsal rami of cervical spinal nerves. A: bilateral head/neck extension; unilateral ipsilateral rotation and lateral flexion.

Splenius cervicis

O: spinous processes T3–T6. I: transverse processes C1–C3/4. N: dorsal rami of cervical spinal nerves. A: bilateral cervical extension; unilateral ipsilateral rotation and lateral flexion.

Anterior scalene

O: transverse processes of C3–C6. I: first rib. N: cervical spinal nerves (C5–C7). A: elevates first rib; aids in neck flexion.

Middle scalene

O: transverse processes of C2–C7. I: first rib. N: cervical spinal nerves (C3–C8). A: elevates first rib; aids in neck flexion.

Posterior scalene

O: transverse processes of C5–C7. I: second rib. N: cervical spinal nerves (C5–C8). A: elevates second rib; aids in neck flexion.