Upper Limb Overview
| Region | Boundaries / Extent |
|---|---|
| Shoulder (pectoral) region | Clavicle, scapula, proximal humerus, and the muscles connecting the upper limb to the trunk |
| Axilla | Pyramidal space between arm and thoracic wall; passageway for vessels and nerves entering the limb |
| Arm (brachium) | Shoulder to elbow; humerus with anterior and posterior fascial compartments |
| Elbow / cubital fossa | Elbow joint posteriorly; cubital fossa anteriorly (triangular fossa overlying the joint) |
| Forearm (antebrachium) | Elbow to wrist; radius and ulna with anterior and posterior fascial compartments |
| Wrist (carpus) | Distal radius/ulna to carpal bones; flexor and extensor retinacula |
| Hand (manus) | Carpus to fingertips; palm, dorsum, and digits |
- Pectoral girdle: clavicle, scapula
- Arm: humerus
- Forearm: radius (lateral), ulna (medial)
- Wrist: 8 carpal bones (proximal row: scaphoid, lunate, triquetrum, pisiform; distal row: trapezium, trapezoid, capitate, hamate)
- Hand: 5 metacarpals, 14 phalanges (proximal, middle, distal, thumb lacks a middle phalanx)
| Joint | Type | Key Movements |
|---|---|---|
| Sternoclavicular | Saddle (functions as ball-and-socket) | Elevation/depression, protraction/retraction, rotation |
| Acromioclavicular | Plane synovial | Gliding; allows scapular rotation on clavicle |
| Glenohumeral (shoulder) | Ball-and-socket synovial | Flexion/extension, abduction/adduction, medial/lateral rotation, circumduction |
| Elbow (humero-ulnar, humeroradial) | Hinge synovial | Flexion/extension |
| Proximal & distal radio-ulnar | Pivot synovial | Pronation/supination |
| Wrist (radiocarpal) | Condyloid synovial | Flexion/extension, abduction/adduction (radial/ulnar deviation) |
| Midcarpal, carpometacarpal, intercarpal | Plane/saddle | Gliding; first CMC joint is a saddle joint enabling thumb opposition |
| Metacarpophalangeal (MCP) | Condyloid | Flexion/extension, abduction/adduction |
| Interphalangeal (PIP, DIP) | Hinge | Flexion/extension only |
- Arm: anterior (flexor, musculocutaneous nerve) and posterior (extensor, radial nerve)
- Forearm: anterior (flexor/pronator, median and ulnar nerves) and posterior (extensor/supinator, radial nerve)
- Hand: thenar, hypothenar, central palmar (lumbricals, interossei, adductor pollicis)
Compartments are enclosed by deep fascia and intermuscular septa, which are clinically relevant to the spread of infection and to compartment syndrome.
| Nerve | Root Values | Chief Motor Function |
|---|---|---|
| Axillary | C5, C6 | Deltoid, teres minor |
| Musculocutaneous | C5, C6, C7 | Anterior arm flexors |
| Median | C5–T1 | Anterior forearm (except FCU, ulnar half FDP), thenar muscles |
| Ulnar | C8, T1 | FCU, ulnar half FDP, most intrinsic hand muscles |
| Radial | C5–T1 | Posterior arm and forearm extensors |
Other named branches (dorsal scapular, long thoracic, suprascapular, thoracodorsal, medial/lateral pectoral, subscapular, intercostobrachial) are covered under the Brachial Plexus section.
Subclavian artery → axillary artery → brachial artery → (radial + ulnar arteries) → superficial and deep palmar arches → digital arteries.
- Named at the outer border of the first rib (subclavian → axillary), at the lower border of teres major (axillary → brachial), and at the neck of the radius (brachial bifurcation).
- Anastomotic networks exist around the scapula, elbow, and wrist (carpal arches), providing collateral circulation.
- Superficial system: dorsal venous network of hand → cephalic vein (lateral) and basilic vein (medial), connected at the elbow by the median cubital vein: the standard site for venepuncture.
- Deep system: paired venae comitantes accompanying the radial, ulnar, brachial arteries → single axillary vein → subclavian vein.
- Basilic vein pierces deep fascia in the arm to join the venae comitantes/brachial veins; cephalic vein ascends in the deltopectoral groove to drain into the axillary vein.
- Superficial lymphatics largely follow the basilic vein → cubital (supratrochlear) nodes → axillary nodes.
- A smaller lateral group follows the cephalic vein directly to infraclavicular/apical axillary nodes or deltopectoral nodes.
- Deep lymphatics accompany the deep vessels directly to axillary nodes.
- All upper limb lymph drains to axillary nodes → apical group → subclavian lymphatic trunk.
| Root | Approximate Area |
|---|---|
| C5 | Lateral arm (over deltoid, "regimental badge" region) |
| C6 | Lateral forearm, thumb, index finger |
| C7 | Middle finger, central palm/dorsum |
| C8 | Ring and little fingers, medial hand |
| T1 | Medial forearm |
| T2 | Medial arm, axilla |
| Movement | Root Value |
|---|---|
| Shoulder abduction | C5 |
| Elbow flexion | C5, C6 |
| Elbow extension | C7, C8 |
| Wrist extension | C6, C7 |
| Wrist flexion | C6, C7, C8 |
| Finger flexion | C7, C8 |
| Finger abduction | T1 |
- Median nerve: palmar aspect of lateral 3½ digits, palm (via palmar cutaneous branch, spared in carpal tunnel syndrome)
- Ulnar nerve: palmar and dorsal aspect of medial 1½ digits, hypothenar region
- Radial nerve (superficial branch): dorsum of lateral hand and dorsal aspect of lateral 3½ digits (excluding nail beds)
- Axillary nerve: small "regimental badge" area over lower deltoid
- Musculocutaneous nerve (as lateral cutaneous nerve of forearm): lateral forearm
- These peripheral nerve territories differ from dermatomes and are essential for localising nerve lesions clinically.
Clavicle, acromion, coracoid process, spine of scapula, deltopectoral groove, medial/lateral epicondyles, olecranon, radial head, cubital fossa creases, anatomical snuffbox, radial and ulnar styloids, pisiform, hook of hamate. Full palpation detail is covered in the Surface Anatomy section.
- Shoulder complex: wide range of motion via combined glenohumeral and scapulothoracic movement (scapulohumeral rhythm), prioritising mobility over stability.
- Elbow and radio-ulnar joints: position the hand in space; flexion/extension plus pronation/supination give the forearm rotational versatility.
- Wrist: fine positional control of the hand; flexion/extension and radial/ulnar deviation.
- Hand: combines power grip, precision grip, pinch, and opposition, enabled by long flexor/extensor tendons (extrinsic) and thenar/hypothenar/interosseous/lumbrical muscles (intrinsic).
- Overall limb design reflects a proximal-to-distal gradient: proximal joints favour mobility, distal structures favour precision.
