Upper Limb Muscles – Origin, Insertion, Innervation, and Action (Vocabulary Flashcards)

Vocabulary flashcards covering the major muscles of the upper limb with their origin, insertion, innervation, and action.

Pectoralis major

Origin: medial clavicle, manubrium and body of sternum, and costal cartilages; Insertion: lateral lip of intertubercular sulcus of the humerus; Innervation: medial and lateral pectoral nerves; Action: flexes, adducts, and medially rotates the humerus.

Pectoralis minor

Origin: ribs 3–5; Insertion: coracoid process; Innervation: medial pectoral nerve; Action: protracts and depresses the scapula; accessory muscle of respiration.

Subclavius

Origin: superior border of first rib and costal cartilage; Insertion: inferior surface of the clavicle; Innervation: nerve to subclavius; Action: anchors and depresses the clavicle.

Serratus anterior

Origin: ribs 1–9; Insertion: medial border of the scapula (costal surface); Innervation: long thoracic nerve; Action: fixes scapula to thoracic wall, abducts the humerus; works with trapezius for arm abduction from 90–180 degrees.

Deltoid

Origin: Anterior fibers from lateral clavicle; Middle fibers from acromion; Posterior fibers from spine of scapula; Insertion: deltoid tuberosity of humerus; Innervation: axillary nerve; Action: Anterior—flexion and internal rotation; Middle—abduction (15–90 degrees); Posterior—extension and external rotation.

Supraspinatus

Origin: supraspinous fossa of scapula; Insertion: greater tubercle of humerus; Innervation: suprascapular nerve; Action: initiates the first 15 degrees of arm abduction.

Infraspinatus

Origin: infraspinous fossa of scapula; Insertion: greater tubercle of humerus; Innervation: suprascapular nerve; Action: external (lateral) rotation of the humerus.

Teres minor

Origin: lateral border of the scapula; Insertion: greater tubercle of humerus; Innervation: axillary nerve; Action: external rotation of the humerus.

Subscapularis

Origin: subscapular fossa of scapula; Insertion: lesser tubercle of humerus; Innervation: upper and lower subscapular nerves; Action: internal rotation of the humerus.

Teres major

Origin: inferior angle of the scapula; Insertion: crest of lesser tubercle of humerus; Innervation: lower subscapular nerve; Action: extension, adduction, and internal rotation of the humerus (same as latissimus dorsi).

Biceps brachii

Origin: short head from coracoid process; long head from supraglenoid tubercle of scapula; Insertion: radial tuberosity of the radius via the bicipital aponeurosis; Innervation: musculocutaneous nerve (C5–C7); Action: flexion and supination of the forearm; long head also assists in arm flexion.

Coracobrachialis

Origin: coracoid process; Insertion: middle third of humerus; Innervation: musculocutaneous nerve (C5–C7); Action: flexion and adduction of the arm.

Brachialis

Origin: anterior midshaft of humerus; Insertion: coronoid process of ulna; Innervation: musculocutaneous nerve (C5–C7); Action: primary flexor of the forearm.

Triceps brachii

Origin: long head – infraglenoid tubercle; lateral head – posterior midshaft; medial head – posterior midshaft; Insertion: olecranon via common tendon; Innervation: radial nerve (C5–T1); Action: extends the elbow; long head can extend the arm.

Anconeus

Origin: lateral epicondyle; Insertion: olecranon process; Innervation: radial nerve (C5–T1); Action: weak forearm extension and stabilizes the humeroulnar joint.

Pronator teres

Origin: medial epicondyle of humerus; Insertion: anterior radius; Innervation: median nerve; Action: pronation of the forearm and weak flexion.

Flexor carpi radialis

Origin: medial epicondyle of humerus; Insertion: radial side of the wrist; Innervation: median nerve; Action: wrist flexion and abduction (radial deviation).

Palmaris longus

Origin: medial epicondyle of humerus; Insertion: palmar aponeurosis; Innervation: median nerve; Action: wrist flexion.

Flexor carpi ulnaris

Origin: medial epicondyle of humerus; Insertion: ulnar side of the wrist (pisiform/hook of hamate and base of 5th metacarpal); Innervation: ulnar nerve; Action: wrist flexion and adduction.

Flexor digitorum superficialis

Origin: medial epicondyle of humerus and anterior radius; Insertion: bases of middle phalanges of digits 2–5; Innervation: median nerve; Action: flexion of the fingers (PIP joints primarily).

Pronator quadratus

Origin: anterior ulna; Insertion: anterior radius; Innervation: anterior interosseous nerve; Action: pronation of the forearm.

Flexor digitorum profundus

Origin: anterior ulna and interosseous membrane; Insertion: bases of distal phalanges 2–5; Innervation: lateral portion (digits 2–3) by anterior interosseous nerve; medial portion (digits 4–5) by ulnar nerve; Action: flexion of the fingers (DIP, PIP, and MCP).

Flexor pollicis longus

Origin: anterior radius; Insertion: distal phalanx of digit 1 (thumb); Innervation: anterior interosseous nerve; Action: flexion of the thumb.

Brachioradialis

Origin: supraepicondylar ridge (lateral); Insertion: distal radius (anterior); Innervation: radial nerve (proper); Action: flexion of the forearm (wrist not moved).

Extensor carpi radialis longus

Origin: supraepicondylar ridge (lateral); Insertion: dorsal surface base of 2nd metacarpal; Innervation: radial nerve (proper); Action: wrist extension and abduction.

Extensor carpi radialis brevis

Origin: lateral epicondyle of humerus; Insertion: dorsal surface base of 3rd metacarpal; Innervation: posterior interosseous nerve; Action: wrist extension and abduction.

Extensor digitorum

Origin: lateral epicondyle of humerus; Insertion: extensor expansion of digits 2–5; Innervation: posterior interosseous nerve; Action: extension of the digits.

Extensor digiti minimi

Origin: lateral epicondyle; Insertion: extensor expansion of digit 5; Innervation: posterior interosseous nerve; Action: extension of digit 5.

Extensor carpi ulnaris

Origin: lateral epicondyle of humerus; Insertion: ulnar side of the wrist; Innervation: posterior interosseous nerve; Action: wrist extension and adduction.

Abductor pollicis longus

Origin: posterior ulna, radius and interosseous membrane; Insertion: base of the first metacarpal; Innervation: posterior interosseous nerve; Action: thumb abduction.

Extensor pollicis brevis

Origin: posterior radius and interosseous membrane; Insertion: base of proximal phalanx of the thumb; Innervation: posterior interosseous nerve; Action: thumb extension.

Extensor pollicis longus

Origin: posterior ulna and interosseous membrane; Insertion: base of distal phalanx of the thumb; Innervation: posterior interosseous nerve; Action: thumb extension.

Extensor indicis

Origin: posterior ulna and interosseous membrane; Insertion: extensor expansion of the index finger; Innervation: posterior interosseous nerve; Action: extension of the index finger.

Supinator

Origin: posterior ulna; Insertion: lateral and anterior radius; Innervation: deep branch of radial nerve; Action: forearm supination.

Lumbrical

Origin: (from notes) nan; Insertion: nan; Innervation: 1st and 2nd lumbricals by median nerve, 3rd and 4th by deep branch of ulnar nerve; Action: flex MCP joints and extend PIP joints.

Carpal tunnel

Definition: The passage in the wrist through which the median nerve passes; contains tendons of flexor digitorum superficialis and flexor digitorum profundus; Innervation: median nerve; Note: site of carpal tunnel syndrome.