clavicle
Meaning of clavicle: The only bony strut between the arm and the trunk, lying under thin skin where it can be seen and felt along its whole length.
Definition of clavicle
The clavicle, commonly called the collarbone, is the slender curved bone running across the top of the chest from the breastbone to the shoulder blade, one on each side. It is the only bony link between the arm and the trunk, holding the shoulder out from the body so the arm can swing freely, and it sits just beneath the skin for its entire length.
What does the bone actually do?
It works as a strut. By propping the shoulder away from the chest wall it gives the arm room to reach overhead, across the body and behind the back, and an arm whose strut is broken hangs closer in and moves poorly. The bone also passes force inward: a push through the hand travels up the arm and crosses the clavicle to reach the ribcage and spine. Underneath it run the large vessels and the bundle of nerves supplying the arm, and the bone shields them. Several muscles anchor to it, including those of the chest, the neck and the front of the shoulder, which is why a broken clavicle is pulled out of line by muscle tension rather than staying neatly in place.
What joints does it form?
| Joint | What it connects | What goes wrong there |
|---|---|---|
| Sternoclavicular | Inner end to the breastbone | Rarely dislocated, but serious when it moves backward toward the windpipe and vessels |
| Acromioclavicular | Outer end to the scapula | Sprained or separated by a fall onto the point of the shoulder |
The inner one is the only true joint anywhere between the whole arm complex and the central skeleton. Everything else holding the shoulder in place is muscle and ligament, which buys enormous range of movement at the cost of stability.
Why does it break so often?
It is slender, it is superficial, and it lies directly in the path of force traveling from the arm to the trunk. A fall onto the shoulder or onto an outstretched hand loads it lengthwise, and the middle third, the narrowest and least supported stretch, gives way most often. Because so little tissue covers the bone, a break usually shows as a visible bump or a step that can be felt. It is also the bone most often broken during birth, when a shoulder is delivered through a tight fit, and those breaks generally heal without lasting trouble. One more quirk is worth knowing: the clavicle is the first bone in the body to start hardening before birth and among the last to finish, with the growth area at the end nearest the breastbone not fusing until well into adult life, so an injury there in a young adult can be a growth plate separation rather than the joint dislocation it resembles.
Also known as
Used in a sentence
An X-ray confirmed a clavicle fracture following the patient's fall onto the shoulder.
Good to know
A clavicle fracture is commonly identified by a visible or palpable deformity along the bone's length, given how little soft tissue covers it compared with most other bones.
Word origin
Where “clavicle” comes from
From Latin clavicula, meaning a small key, a diminutive of clavis, meaning key, referring to the bone's resemblance to an ancient key in shape.