Shoulder is the most mobile joint in the human body. The ball joint can rotate around 3 axes, so it alone provides our hands with almost 50% of their mobility. This is all the more impressive when one considers that all that movement must not impede blood flow through the appendage.

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One of these bones is not like the others, one of these bones does not belong.

It is clavicle. Clavicle is dermal bone, so it develops by a different process than most other bones. This means it has different internal structure and is therefore more fragile. Broken clavicle is therefore a fairly common injury.