Phalanx
Long bone, part of the appendicular skeleton
Also known as: Finger bone or toe bone
Classification
Long bone, part of the appendicular skeleton
Dimensions
Small and slender, typically ranging from a fraction of an inch to a few inches in length depending on the animal species, featuring a slightly narrower middle shaft and wider ends.
Key Features
Cylindrical or slightly curved shape with a smooth central shaft and distinct, gently rounded ends designed to connect with neighboring bones. Often shows a slightly pinched waist.
Similar Bones
Can be easily confused with small metacarpals or metatarsals from the hands and feet, but typically lacks the broader, flat joint surfaces found at the ends of those palm and arch bones.
Across Species
In humans and many land mammals, these bones form the digits of hands and feet, granting dexterity and support. In swimming mammals like whales, they are enclosed inside flippers and multiply in number to form a wide paddle. In running animals like horses, the lower elements are heavily fused and adapted into a single powerful hoof-bearing column.
Evolutionary History
Evolving from the fin rays of ancient lobe-finned fish that ventured into shallow waters, these bones underwent a structural shift to support weight on land, eventually diversifying into the gripping hands, digging paws, and flying wings of modern tetrapods.
Photography Tips
Place the bone on a solid, non-glare background next to a common scale reference like a coin or ruler. Use soft overhead lighting to highlight the curved contours and surface texture.