Overview
The upper limb muscles control powerful yet precise movements of the shoulder, arm, forearm, and hand. For exams and clinical practice you must know the core facts: origin, insertion, nerve supply, and the main action of each muscle. This summary table organises the major muscles of the pectoral region, shoulder, arm, forearm, and hand for rapid review.
Use this table alongside regional pages such as the brachial plexus, arm muscles, and intrinsic hand muscles to integrate muscle anatomy with nerve supply and clinical correlations.
Pectoral Region and Axio-Appendicular Muscles
These muscles connect the upper limb to the axial skeleton and stabilise the shoulder girdle.
Pectoral Region
| Muscle | Origin | Insertion | Nerve Supply | Main Action |
|---|---|---|---|---|
| Pectoralis Major | Medial clavicle; sternum; costal cartilages 1–6 | Lateral lip of intertubercular sulcus of humerus | Medial and lateral pectoral nerves (C5–T1) | Adduction and medial rotation of arm; clavicular head flexes arm |
| Pectoralis Minor | Ribs 3–5 near costal cartilages | Coracoid process of scapula | Medial pectoral nerve (C8, T1) | Stabilises scapula; pulls it anteriorly and inferiorly |
| Subclavius | 1st rib and costal cartilage | Inferior surface of middle third of clavicle | Nerve to subclavius (C5, C6) | Depresses clavicle; protects subclavian vessels |
| Serratus Anterior | External surfaces of ribs 1–8 | Costal surface of medial border of scapula | Long thoracic nerve (C5–C7) | Protracts and rotates scapula; holds scapula against thoracic wall |
Scapulohumeral (Intrinsic Shoulder) Muscles
These muscles act directly on the glenohumeral joint and form the dynamic stabilisers of the shoulder. The rotator cuff is discussed in detail under rotator cuff muscles.
Shoulder Muscles
| Muscle | Origin | Insertion | Nerve Supply | Main Action |
|---|---|---|---|---|
| Deltoid | Lateral third of clavicle; acromion; spine of scapula | Deltoid tuberosity of humerus | Axillary nerve (C5, C6) | Major abductor of arm (15–90°); anterior fibres flex and medially rotate; posterior fibres extend and laterally rotate |
| Supraspinatus | Supraspinous fossa of scapula | Superior facet of greater tubercle of humerus | Suprascapular nerve (C5, C6) | Initiates abduction (0–15°); part of rotator cuff |
| Infraspinatus | Infraspinous fossa of scapula | Middle facet of greater tubercle | Suprascapular nerve (C5, C6) | Lateral rotation of arm; rotator cuff |
| Teres Minor | Lateral border of scapula | Inferior facet of greater tubercle | Axillary nerve (C5, C6) | Lateral rotation of arm; assists adduction; rotator cuff |
| Subscapularis | Subscapular fossa (costal surface of scapula) | Lesser tubercle of humerus | Upper and lower subscapular nerves (C5–C7) | Medial rotation and adduction of arm; rotator cuff |
| Teres Major | Inferior angle and lower lateral border of scapula | Medial lip of intertubercular sulcus | Lower subscapular nerve (C5–C7) | Adduction and medial rotation of arm; assists extension |
Arm — Anterior Compartment
The anterior compartment flexes the shoulder and elbow and is innervated predominantly by the musculocutaneous nerve. For more, see muscles of the anterior arm.
Flexor Muscles of the Arm
| Muscle | Origin | Insertion | Nerve Supply | Main Action |
|---|---|---|---|---|
| Biceps Brachii | Long head: Supraglenoid tubercle; Short head: Coracoid process | Radial tuberosity and bicipital aponeurosis | Musculocutaneous nerve (C5, C6) | Powerful supinator; flexes elbow; assists shoulder flexion |
| Brachialis | Distal half of anterior humerus | Coronoid process and tuberosity of ulna | Musculocutaneous nerve (C5, C6) with small radial nerve contribution | Primary flexor of elbow in all positions |
| Coracobrachialis | Coracoid process | Middle third of medial humerus | Musculocutaneous nerve (C5–C7) | Flexion and adduction of shoulder; resists dislocation of head of humerus |
Arm — Posterior Compartment
The posterior compartment extends the elbow and is innervated by the radial nerve.
Extensor Muscles of the Arm
| Muscle | Origin | Insertion | Nerve Supply | Main Action |
|---|---|---|---|---|
| Triceps Brachii | Long head: Infraglenoid tubercle; Lateral head: Posterior humerus above radial groove; Medial head: Posterior humerus below radial groove | Olecranon of ulna | Radial nerve (C6–C8) | Principal extensor of elbow; long head stabilises shoulder joint |
| Anconeus | Lateral epicondyle of humerus | Lateral surface of olecranon and proximal ulna | Radial nerve (C7, C8, T1) | Assists triceps in elbow extension; stabilises elbow joint |
Forearm — Anterior Compartment
These muscles flex the wrist and digits and pronate the forearm. They are mainly supplied by the median nerve, with ulnar nerve to the medial flexors. Clinical nerve patterns are detailed under median nerve and related pages.
Superficial and Intermediate Flexors
| Muscle | Origin | Insertion | Nerve Supply | Main Action |
|---|---|---|---|---|
| Pronator Teres | Medial epicondyle of humerus; coronoid process of ulna | Lateral surface of mid-radius | Median nerve (C6, C7) | Pronation of forearm; weak elbow flexion |
| Flexor Carpi Radialis | Medial epicondyle via common flexor origin | Base of 2nd (sometimes 3rd) metacarpal | Median nerve (C6, C7) | Flexes and abducts wrist |
| Palmaris Longus | Medial epicondyle | Flexor retinaculum and palmar aponeurosis | Median nerve (C7, C8) | Weak wrist flexion; tenses palmar fascia |
| Flexor Carpi Ulnaris | Medial epicondyle; olecranon and posterior ulna | Pisiform; hook of hamate; base of 5th metacarpal | Ulnar nerve (C7, C8) | Flexes and adducts wrist |
| Flexor Digitorum Superficialis | Medial epicondyle; ulnar collateral ligament; coronoid process; proximal radius | Sides of shafts of middle phalanges of digits 2–5 | Median nerve (C7, C8, T1) | Flexes PIP joints of digits 2–5; assists MCP and wrist flexion |
Deep Flexors
| Muscle | Origin | Insertion | Nerve Supply | Main Action |
|---|---|---|---|---|
| Flexor Digitorum Profundus | Proximal three-quarters of ulna and interosseous membrane | Bases of distal phalanges of digits 2–5 | Lateral part: Anterior interosseous branch of median nerve (C8, T1); Medial part: Ulnar nerve (C8, T1) | Flexes DIP joints of digits 2–5 |
| Flexor Pollicis Longus | Anterior radius and interosseous membrane | Base of distal phalanx of thumb | Anterior interosseous nerve (C8, T1) | Flexes thumb IP joint |
| Pronator Quadratus | Distal quarter of ulna | Distal quarter of radius | Anterior interosseous nerve (C8, T1) | Prime pronator of forearm; binds radius and ulna together |
Forearm — Posterior Compartment
These muscles extend the wrist and digits and supinate the forearm. They are supplied by the radial nerve and its deep branches. Related nerve pathways are summarised under radial nerve.
Superficial Extensors
| Muscle | Origin | Insertion | Nerve Supply | Main Action |
|---|---|---|---|---|
| Brachioradialis | Lateral supracondylar ridge of humerus | Styloid process of radius | Radial nerve (C5–C7) | Flexes elbow in mid-pronation ("drinking muscle") |
| Extensor Carpi Radialis Longus | Lateral supracondylar ridge | Base of 2nd metacarpal | Radial nerve (C6, C7) | Extends and abducts wrist |
| Extensor Carpi Radialis Brevis | Lateral epicondyle of humerus | Base of 3rd metacarpal | Deep branch of radial nerve (C7, C8) | Extends and abducts wrist |
| Extensor Digitorum | Lateral epicondyle | Extensor expansions of digits 2–5 | Posterior interosseous nerve (C7, C8) | Extends MCP and IP joints of digits 2–5 |
| Extensor Digiti Minimi | Lateral epicondyle | Extensor expansion of 5th digit | Posterior interosseous nerve (C7, C8) | Extends little finger |
| Extensor Carpi Ulnaris | Lateral epicondyle; posterior ulna | Base of 5th metacarpal | Posterior interosseous nerve (C7, C8) | Extends and adducts wrist |
Deep Extensors
| Muscle | Origin | Insertion | Nerve Supply | Main Action |
|---|---|---|---|---|
| Supinator | Lateral epicondyle; radial collateral and annular ligaments; supinator crest of ulna | Proximal third of radius (lateral, posterior, and anterior surfaces) | Deep branch of radial nerve (C6, C7) | Supination of forearm (especially slow, unresisted) |
| Abductor Pollicis Longus | Posterior ulna and radius; interosseous membrane | Base of 1st metacarpal | Posterior interosseous nerve (C7, C8) | Abducts and extends thumb at CMC joint |
| Extensor Pollicis Brevis | Posterior radius; interosseous membrane | Base of proximal phalanx of thumb | Posterior interosseous nerve (C7, C8) | Extends thumb at MCP joint |
| Extensor Pollicis Longus | Posterior ulna; interosseous membrane | Base of distal phalanx of thumb | Posterior interosseous nerve (C7, C8) | Extends thumb at IP joint |
| Extensor Indicis | Posterior ulna; interosseous membrane | Extensor expansion of index finger | Posterior interosseous nerve (C7, C8) | Independent extension of index finger |
Intrinsic Muscles of the Hand
The intrinsic hand muscles enable precision grip and fine movements. Detailed descriptions are given in intrinsic muscles of the hand.
Major Intrinsic Groups (Summary)
| Group | Main Muscles | Key Innervation | Core Actions |
|---|---|---|---|
| Thenar Muscles | Abductor pollicis brevis; Flexor pollicis brevis; Opponens pollicis | Recurrent branch of median nerve | Thumb abduction, flexion, opposition |
| Adductor Pollicis | Adductor pollicis (oblique and transverse heads) | Deep branch of ulnar nerve | Adduction of thumb; power grip |
| Hypothenar Muscles | Abductor digiti minimi; Flexor digiti minimi brevis; Opponens digiti minimi | Deep branch of ulnar nerve | Movements of little finger |
| Lumbricals | 1st–4th lumbricals | Lateral two: Median nerve; Medial two: Ulnar nerve | Flex MCP and extend IP joints of digits 2–5 |
| Interossei | Palmar interossei (PAD); Dorsal interossei (DAB) | Deep branch of ulnar nerve | PAD: adduct digits; DAB: abduct digits; assist lumbricals |
Exam Strategy
To efficiently memorise upper limb muscles, group them by compartments and nerve supply. Learn one column at a time: first action, then nerve, then origin and insertion. Combine this table with brachial plexus and nerve injury pages to understand patterns such as wrist drop, claw hand, and thenar wasting for fast clinical recall.