Upper limb

Clavicle

Before you say anything

The clavicle is the easiest bone in the box to identify and the one students most often hand back with the wrong side. It is the only bony strut between the upper limb and the axial skeleton, it is the first bone in the body to start ossifying and the last epiphysis to fuse, and it is the only long bone that is horizontal. Do not describe it before you have turned it the right way up: the rough, grooved surface goes downwards.

Which side? Three checks

Hold it like this first: Hold it horizontally with the flattened end laterally, the rounded end medially, the rough grooved surface downwards, and the convexity of the medial two-thirds facing forwards.

Check 1 — Compare the two ends
One end is rounded and quadrangular, the other is flattened from above downwards
The flattened end is the acromial end and points to the side the bone belongs to
Check 2 — Read the curves of the shaft
The medial two-thirds is convex forwards, the lateral third concave forwards
With the convexity forwards, the lateral third sweeps back towards its own shoulder
Check 3 — Feel the two surfaces
One surface is smooth, the other carries a groove for subclavius and rough markings near the lateral end
The rough, grooved surface is inferior, so the bone can only lie one way up

Drill this against the clock →

Work it out, one rung at a time

Answer each question in your head first. Then open it.

1
Identify
What kind of bone is this?
2
Orient
Which way up does it go?
3
Side
Which side?
4
Landmarks
What can you point out?
5
Attachments
What is attached?
6
Applied
Why does it matter?

Landmarks to point out

Sternal end
Medial end, rounded and quadrangular
Articulates with the manubrium and the first costal cartilage; carries the only secondary centre of ossification.
Acromial end
Lateral end, flattened from above downwards
Articulates with the acromion; the flattening is the quickest side clue.
Conoid tubercle
Inferior surface, at the junction of the middle and lateral thirds
Gives attachment to the conoid part of the coracoclavicular ligament, which suspends the limb from the clavicle.
Trapezoid ridge
Inferior surface, running forwards and laterally from the conoid tubercle
Gives attachment to the trapezoid part of the coracoclavicular ligament.
Subclavian groove
Along the inferior surface of the middle third
Lodges subclavius, which cushions the subclavian vessels from a fractured shaft.
Impression for the costoclavicular ligament
Inferior surface of the medial end
Anchors the medial end to the first rib and limits elevation of the shoulder.

Say these first

Horizontal, S-shaped, no medullary cavity
One end rounded, the other flattened
Grooved, roughened inferior surface

Do not confuse it with

A rib
A rib has a head, neck and tubercle at one end and a costal groove along its lower border; the clavicle has neither and its two ends differ in shape rather than in curvature.

Examiner trap

Saying the clavicle ossifies in cartilage like other long bones. It is largely membranous, which is why it has no medullary cavity — and that fact is usually the follow-up question.

Memory hook

First to ossify, last to fuse.

Why it matters

The commonest site of fracture is the junction of the middle and lateral thirds: the lateral fragment is pulled down by the weight of the limb and the medial fragment pulled up by sternocleidomastoid.
Subclavius lies between the bone and the subclavian vessels, which is why a fractured clavicle rarely tears them.
Because the clavicle is the only bony strut to the trunk, its absence in cleidocranial dysostosis lets a patient approximate the shoulders in front of the chest.

Senior’s 30-second takeaway

Clavicle — the whole bench in four lines. Read this on the way in.

If you see this: A horizontal S-shaped bone · One end rounded, one flattened · A grooved, rough undersurface
If asked to identify it: This is a clavicle; the flattened acromial end and the grooved inferior surface identify it and give the side.
If asked one more: It is the first bone to ossify and the last to fuse, and it ossifies in membrane.
If asked why it matters: It is the commonest fractured long bone, typically at the junction of the middle and lateral thirds.

Then stop. Let the examiner ask the next question.

Clavicle

Before you say anything

Which side? Three checks

Work it out, one rung at a time

Landmarks to point out

Senior’s 30-second takeaway

Attachments

Articulations

Ossification

Viva voce

🩺 Before you say anything

Which side? Three checks

Work it out, one rung at a time

Landmarks to point out

Senior’s 30-second takeaway

Attachments

Articulations

Ossification

🎙️ Viva voce

Before you say anything

Viva voce