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Editorial & review policyHuman Anatomy · Upper limb
The upper limb gave up stability to buy reach and dexterity. Its whole bony attachment to the trunk is one small joint at the sternum. Everything that follows — the mobility, the vulnerability, the nerve injuries — comes from that decision.
Compare the two limbs for a moment. The lower limb attaches to the axial skeleton through the sacroiliac joint, a massive, almost immobile articulation built to transmit body weight. The upper limb attaches through the sternoclavicular joint — a small joint at the top of the sternum, and the only bony connection there is.
Everything else holding the shoulder girdle on is muscle. The scapula does not articulate with the ribs at all; it floats on them, slung in muscle, free to slide and rotate. That arrangement lets you place your hand almost anywhere in a large sphere around you, and it is why the upper limb is so much more mobile and so much less stable than the lower.
Figure 1 · Bones of the upper limb
Illustration to be added
A full plate of the upper limb skeleton, anterior and posterior views side by side, articulated. Name every bone: clavicle, scapula, humerus, radius, ulna, the eight carpals individually, five metacarpals numbered, and the phalanges. On the humerus label head, anatomical neck, greater and lesser tubercles, intertubercular groove, surgical neck, deltoid tuberosity, radial groove, medial and lateral epicondyles, trochlea, capitulum, olecranon fossa. On the scapula label spine, acromion, coracoid process, glenoid fossa, the three borders and three angles. On the clavicle mark the junction of the middle and lateral thirds. Bone in warm ivory, navy line work, gold leader lines, on white.
An S-shaped strut running from the sternum to the acromion. It is easy to overlook, and it does three things. It holds the shoulder out away from the chest wall so the arm can swing freely. It transmits force from the arm to the trunk. And it shields the vessels and nerves passing beneath it into the limb.
| Feature | Detail | Why it matters |
|---|---|---|
| Shape | Convex forwards medially, concave forwards laterally | The change in curvature falls at the junction of the middle and lateral thirds, which is the weakest point. |
| Commonest fracture site | Junction of middle and lateral thirds | Usually from a fall on the outstretched hand or the point of the shoulder. The medial fragment rides up, pulled by sternocleidomastoid. |
| Ossification | The first bone in the body to begin ossifying, and the last to finish. The only long bone that ossifies in membrane. | A favourite examination question, and worth knowing it is an exception. |
| Relations beneath | Subclavian vessels and the brachial plexus | These are what a badly displaced fracture can threaten. |
A flat triangular bone lying on the back of the chest wall, over ribs two to seven. Learn it as a set of landmarks, because almost all of them are palpable and you will use them constantly.
| Group | Landmarks | Note |
|---|---|---|
| Borders | Superior, medial (vertebral), lateral (axillary) | The medial border is what lifts away from the chest in winging. |
| Angles | Superior, inferior, lateral | The inferior angle is an easy landmark to follow during movement. |
| Spine and acromion | The spine runs across the back and broadens into the acromion | The acromion forms the point of the shoulder and the roof over the cuff tendons. |
| Coracoid process | A hooked projection pointing forwards below the clavicle | Attachment for pectoralis minor, coracobrachialis and the short head of biceps. |
| Glenoid fossa | A shallow, pear-shaped socket at the lateral angle | Roughly a third of the humeral head sits against it. That shallowness is the shoulder's whole story. |
| Fossae | Supraspinous and infraspinous behind, subscapular in front | Each houses the cuff muscle named after it. |
The largest bone of the limb, and the one whose landmarks matter most clinically, because three major nerves lie against it at three predictable points.
| Region | Features |
|---|---|
| Upper end | Head; anatomical neck, the old growth plate line just below the articular margin; greater and lesser tubercles with the intertubercular (bicipital) groove between them, carrying the long head of biceps; surgical neck below the tubercles. |
| Shaft | Deltoid tuberosity on the lateral side; the radial (spiral) groove running obliquely down the back, carrying the radial nerve. |
| Lower end | Trochlea medially, articulating with the ulna; capitulum laterally, with the radius; medial and lateral epicondyles; coronoid and radial fossae in front, olecranon fossa behind. |
Anatomical neck against surgical neck
The anatomical neck is the line where the old growth plate sat, immediately below the head. The surgical neck is the narrowing below the tubercles, and it is called surgical because that is where fractures actually happen. The axillary nerve winds round it, which is why an axillary nerve lesion so often accompanies that fracture.
Figure 2 · Nerves at risk along the humerus
That figure is worth learning as four pairings rather than four separate facts. Each site has a nerve, and each nerve has a recognisable deficit. If you know the pairing you can examine the right thing immediately after an injury, rather than testing everything.
Two bones side by side, joined along their length by an interosseous membrane. In the anatomical position the radius is lateral, on the thumb side, and the ulna is medial.
| Radius | Ulna | |
|---|---|---|
| Size | Small head, large lower end | Large upper end, small lower end |
| Upper end | Disc-shaped head, neck, and the radial tuberosity for the biceps tendon | Olecranon behind, coronoid process in front, and the trochlear notch between them gripping the humerus |
| Lower end | Broad, with a styloid process laterally. Carries most of the wrist joint. | Small head with a styloid process medially. Does not reach the carpus directly. |
| Role | Takes most of the load at the wrist; rotates around the ulna in pronation and supination | The stable one. Forms the hinge at the elbow. |
The two styloid processes are not level
The radial styloid lies about a centimetre lower than the ulnar styloid. This normal relationship is lost after a displaced wrist fracture, and comparing the two sides is a quick clinical check that costs nothing.
Figure 3 · The eight carpal bones
Eight small bones in two rows of four, named lateral to medial in each row. They are worth learning in order, because clinical descriptions assume you know where each one sits.
| Bone | Worth knowing |
|---|---|
| Scaphoid | The most commonly fractured carpal. Tenderness in the anatomical snuffbox suggests it. Its blood supply enters at the far end and runs backwards, so a fracture across the waist can starve the proximal fragment. |
| Lunate | The most commonly dislocated carpal. Sits in the middle of the proximal row. |
| Pisiform | A sesamoid bone within the tendon of flexor carpi ulnaris. Easily felt at the base of the hypothenar eminence. |
| Hamate | Has a hook projecting forwards, forming the medial wall of the carpal tunnel and a boundary of the ulnar tunnel. |
| Trapezium | Carries the saddle joint of the thumb, which is why the thumb can be opposed. |
The carpus is not flat. The bones form an arch, concave forwards, and the flexor retinaculum bridges across it to complete the carpal tunnel. The median nerve and the long flexor tendons pass through that tunnel, which is why swelling anywhere inside it produces symptoms in the median nerve territory.
Figure 4 · The carpal bones and the carpal tunnel
Illustration to be added
The wrist from the palmar side with all eight carpal bones individually named and the two rows colour-separated. A second panel showing a cross-section through the carpus, demonstrating the carpal arch concave forwards, with the flexor retinaculum bridging it to complete the carpal tunnel. Inside the tunnel show the median nerve and the long flexor tendons in their correct relative positions, and mark the pisiform and hook of hamate medially and the tubercles of scaphoid and trapezium laterally as the four attachment points of the retinaculum. Bone in warm ivory, nerve gold, tendons pale, retinaculum as a heavy navy band.
Five metacarpals, numbered from the thumb, each with a base, shaft and head — the heads are your knuckles. Then fourteen phalanges: three in each finger, two in the thumb. The thumb's metacarpal is set at an angle to the others and rotated, which is what allows opposition.
Almost the entire upper limb skeleton is palpable, which is unusual and extremely useful. Find these on yourself now; you will use every one of them.
| Landmark | Where to find it |
|---|---|
| Whole clavicle | Along its length, from sternum to acromion |
| Acromion and the acromioclavicular joint | Follow the clavicle laterally until it meets the flat shelf of the acromion |
| Coracoid process | Just below the outer third of the clavicle, pressing firmly; it is tender in everyone |
| Greater tubercle | The most lateral bony point of the shoulder, below the acromion |
| Spine of scapula and inferior angle | Across the back; follow the spine medially and the angle downwards |
| Medial and lateral epicondyles, olecranon | At the elbow. In extension the three lie in a straight line; in flexion they form a triangle. |
| Radial head | Just distal to the lateral epicondyle; rotate the forearm and feel it turn |
| Styloid processes | At the wrist, radial lower than ulnar |
| Anatomical snuffbox | The hollow at the base of the thumb when it is extended; the scaphoid lies in its floor |
| Pisiform and hook of hamate | At the base of the hypothenar eminence |
The elbow triangle
With the elbow extended, the two epicondyles and the tip of the olecranon lie in a straight line. With it flexed to a right angle they form an equilateral triangle. This relationship is preserved in a supracondylar fracture and disturbed in a dislocation, so checking it helps distinguish the two before any imaging arrives.
One small joint at the sternum, and everything else is muscle. This explains the mobility, the instability and why scapular control matters so much.
Anatomical is the old growth plate line just below the head. Surgical is below the tubercles and is where fractures occur, taking the axillary nerve with them.
Learn them as sites: surgical neck, radial groove, medial epicondyle, supracondylar. Each site has one nerve and one deficit.
The order is only useful if you can point to them. Snuffbox tenderness means scaphoid; that is the clinically loaded one.
The radial styloid sits lower. Losing that relationship is a sign of a displaced wrist fracture.
It takes seconds and it separates a dislocation from a fracture at the bedside.
Ten questions on this chapter. Tap one to see the answer and the reasoning.
Answer: (B) The sternoclavicular joint. Everything else holding the shoulder girdle on is muscular, which is why the limb is so mobile and so dependent on muscular control.
Answer: (C) Where its curvature changes, which is its weakest point. The medial fragment is then pulled upwards by sternocleidomastoid.
Answer: (C) The axillary nerve winds around the surgical neck. Test sensation over the outer shoulder rather than deltoid power, which will be limited by pain anyway.
Answer: (B) The radial nerve lies directly against the bone in the radial groove. Triceps is often spared because its branches leave the nerve higher up.
Answer: (C) The scaphoid. Tenderness in the anatomical snuffbox suggests it, and its blood supply enters distally, so a waist fracture can starve the proximal fragment.
Answer: (C) The radial styloid sits roughly a centimetre lower. Loss of this relationship suggests a displaced wrist fracture, and comparing sides takes seconds.
Answer: (B) They form a triangle in flexion and a straight line in extension. The relationship is preserved in supracondylar fracture and disturbed in dislocation.
Answer: (B) The median nerve and the long flexor tendons, beneath the flexor retinaculum bridging the carpal arch. Anything raising pressure inside affects the median nerve.
Answer: (B) It is a sesamoid within the flexor carpi ulnaris tendon, easily palpated at the base of the hypothenar eminence, and it sits in the proximal row.
Answer: (B) It is the only long bone to ossify in membrane, and it is both the first bone to begin ossifying and among the last to finish.
Everything on this page, in one screen
| Book | What it adds here |
|---|---|
| B D Human Anatomy, Volume 1: Upper Limb and Thorax Chaurasia |
The standard Indian regional text for this limb, at exactly the level examinations expect. |
| Anatomy and Human Movement: Structure and Function Palastanga, Field and Soames |
Bony landmarks presented alongside what attaches to them and what that means for movement. |
| Gray's Atlas of Anatomy Drake, Vogl and Mitchell |
Keep it open at the upper limb plates while you read this chapter. |
| Surface Anatomy Lumley |
For the palpation section. Written around what can actually be felt on a living person. |
Reviewed by the Physiotherapist India Team. · Human Anatomy contents