Surface anatomy of the upper limb

Overview

Surface anatomy connects an external landmark to the structures beneath it. A bony prominence helps locate a joint; a visible tendon helps identify an artery or nerve nearby.

This turns a diagram into an examination of a living person.

Clavicle and scapula

The clavicle is subcutaneous along its length. Follow it from the sternoclavicular joint to the lateral acromioclavicular joint.

The acromion forms the palpable top of the shoulder; the scapular spine runs medially from it across the back.

The medial scapular border and inferior angle can usually be felt posteriorly. With the arm by the side, the inferior angle is approximately at the seventh rib or T7 level.

Its position changes with scapular rotation, so it is not a fixed level in every arm posture.

Axillary folds and the deltopectoral groove

Pectoralis major creates the anterior axillary fold. Latissimus dorsi and teres major create the posterior fold. With the arm abducted, these folds outline the axillary space containing the artery, vein, plexus and lymph nodes.

The deltopectoral groove lies between deltoid and pectoralis major. The cephalic vein runs here, then pierces the clavipectoral fascia to join the axillary vein.

The groove is therefore a useful route into deeper anatomy without treating the whole anterior shoulder as one undifferentiated muscle mass.

Serratus anterior can be assessed by asking the patient to push against a wall. A prominent medial scapular border suggests loss of its stabilising action. Trapezius is assessed separately with shoulder shrug and scapular position.

Arm and elbow landmarks

Biceps forms the anterior arm contour. Its distal tendon becomes prominent with resisted flexion or supination.

The medial bicipital groove marks the course of the brachial neurovascular bundle, although depth varies with body habitus.

At the elbow, identify the medial and lateral epicondyles and the olecranon. They form a line in extension and a triangle in flexion.

The radial head can be felt just distal to the lateral epicondyle and moves beneath the fingers during pronation and supination.

The ulnar nerve lies behind the medial epicondyle. Pressure or percussion there can produce tingling down the medial hand, but repeated hard percussion is unnecessary.

The olecranon bursa lies superficially between skin and the posterior olecranon.

Cubital fossa

The cubital fossa is the triangular hollow in front of the elbow. Its superior boundary is an imaginary line between the epicondyles. Brachioradialis forms the lateral boundary and pronator teres the medial boundary.

Brachialis and supinator form the floor. Skin, superficial fascia, deep fascia and the bicipital aponeurosis form the roof. The median cubital vein commonly crosses the superficial roof, although its pattern is variable.

From lateral to medial the principal deep structures are radial nerve, biceps tendon, brachial artery and median nerve. The radial nerve lies towards the lateral edge, under brachioradialis.

The commonly taught tendon–artery–nerve sequence refers to the more central three structures.

The bicipital aponeurosis passes medially from the tendon into forearm fascia and separates superficial veins from deeper neurovascular structures. It offers some protection, rather than forming an impenetrable barrier.

Pulses and vessel landmarks

For the radial pulse, support the forearm with the palm upwards and use the finger pads. The artery is superficial distally, with the radius providing a firm background. Compare sides when a vascular injury is suspected.

Wrist tendons and retinacula

Flex the wrist gently against resistance to reveal the anterior tendons. Flexor carpi radialis lies on the radial side. Flexor carpi ulnaris is medial and ends at the pisiform.

Palmaris longus, when present, appears centrally and continues into the palmar aponeurosis.

Palmaris longus may be absent, so its absence is not a sign of tendon rupture. The median nerve lies deep in this region and cannot be identified safely just by assuming that every central cord is a tendon.

The flexor retinaculum attaches laterally to the scaphoid tubercle and trapezium, and medially to the pisiform and hook of hamate. It forms the roof of the carpal tunnel.

The median nerve and nine tendons pass beneath it: four superficialis, four profundus and one flexor pollicis longus.

Flexor carpi radialis occupies a separate compartment rather than the main carpal tunnel. Palmaris longus and the ulnar neurovascular bundle pass superficial to the retinaculum.

These distinctions are useful when interpreting a penetrating wrist wound.

Posteriorly, the distal radius has a palpable dorsal tubercle, often called Lister's tubercle. Extensor pollicis longus turns around its ulnar side before running towards the thumb.

The extensor retinaculum holds the extensor tendons close to the wrist.

Anatomical snuffbox and hand

Extend the thumb to reveal the hollow on the dorsolateral wrist. Abductor pollicis longus and extensor pollicis brevis form the lateral boundary; extensor pollicis longus forms the medial boundary.

The floor includes scaphoid and trapezium. The radial artery crosses the floor, while the cephalic vein and superficial radial nerve branches lie in the roof.

This difference in depth matters: they are not all side-by-side contents on the same plane.

Palpate the scaphoid tubercle on the palmar radial wrist and the pisiform on the palmar ulnar wrist. The hook of hamate lies distal and lateral to the pisiform and is deeper to palpation.

From radial to ulnar, proximal carpals are scaphoid, lunate, triquetrum and pisiform; distal carpals are trapezium, trapezoid, capitate and hamate.

The thenar eminence is the muscular mound at the thumb base; the hypothenar eminence lies at the little-finger base. Skin creases are useful orientation marks but do not coincide exactly with every underlying joint.

Observe the knuckles and nail direction during finger flexion to assess rotation.

Functional surface tests

To test profundus, hold the middle phalanx and ask for distal joint flexion. To test superficialis, hold the other fingers extended and ask the target finger to flex at its proximal interphalangeal joint.

Anatomical variation can complicate isolated little-finger superficialis testing.

Clinical relevance

Scaphoid injury

How it happens: A fall transmits force through the radial carpus and may fracture the scaphoid.

What you see: Snuffbox or scaphoid-tubercle tenderness and painful use raise suspicion, even with a normal initial radiograph.

Olecranon bursitis

How it happens: Pressure or inflammation distends the superficial bursa behind the olecranon.

What you see: A local posterior swelling may coexist with relatively preserved elbow movement. Marked pain with joint movement suggests deeper involvement.

Venepuncture and wrist wounds

How it happens: A needle or penetrating wound passes beyond a visible vein or tendon into neighbouring structures.

What you see: Altered perfusion, sensory loss or loss of a specific active movement identifies possible vascular, nerve or tendon injury.

Quick revision

• Anterior axillary fold is pectoralis major; posterior fold is latissimus and teres major.
• Cephalic vein occupies the deltopectoral groove.
• Brachial artery lies medial to the biceps tendon at the elbow.
• Ulnar nerve passes behind the medial epicondyle.
• Radial pulse lies lateral to flexor carpi radialis.
• Snuffbox floor carries radial artery; roof carries superficial radial branches and cephalic vein; median nerve and nine flexor tendons occupy the main carpal tunnel.

Sources: Snell's Clinical Anatomy by Regions, supplied Upper Limb chapter; UHS PGET Paper I MBBS Table of Specifications. Supplementary clinical testing and developmental context follow standard examination conventions and Duke Embryology where relevant. Picture links are visual study resources. Text and tables written independently for The House Job.

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