Clavicle
Long Bone, part of the appendicular skeleton
Also known as: Collarbone
Classification
Long Bone, part of the appendicular skeleton
Dimensions
Slender, S-shaped bone that typically spans several inches from the breastbone to the outer shoulder blade, acting as a structural strut.
Key Features
Smooth, elongated, S-curve shape with a flattened outer end that connects to the shoulder blade and a bulkier, blocky inner end that connects to the breastbone.
Similar Bones
Ribs are curved, but they are typically C-shaped and more uniform in thickness compared to the distinct S-curve and varied ends of the collarbone.
Across Species
In humans and tree-climbing animals, the collarbone is well-developed to allow a wide range of arm movement. In running mammals like horses and dogs, the collarbone is greatly reduced or missing entirely to allow the front limbs to swing strictly forward and backward for greater running speed.
Evolutionary History
The collarbone is an ancient element found in many tetrapods, originating from dermal shoulder armor in early fish ancestors. Over millions of years, it transitioned from a rigid protective chest plate into a flexible brace supporting active shoulder mobility.
Photography Tips
Photograph the entire length of the bone from a top-down view against a neutral background, using soft side lighting to highlight the gentle S-curve and distinctive knobby ends alongside a standard ruler for scale.