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
Ranging from tiny, stubby pieces measuring less than a centimeter in smaller digits up to several centimeters long in larger animals, featuring a slender middle shaft with widened, smooth ends.
Key Features
Look for a miniature long bone shape: a smooth, slightly curved central shaft tucked between two wider, rounded ends designed to connect neatly with neighboring bones.
Similar Bones
Can be confused with metacarpals or metatarsals from the central palm or foot area; however, finger bones are generally smaller, more slender, and lack the broad, flat joint surfaces found at the hand-to-wrist or foot-to-ankle junctions.
Across Species
While humans have three of these in each finger (and two in the thumb), whales and dolphins have evolved many more packed inside their flippers to create broad swimming paddles, and horses have fused and modified theirs into a single massive hoof-bearing bone at the ground.
Evolutionary History
Spanning hundreds of millions of years, these digits evolved from the flexible fin rays of ancient lobe-finned fish, transforming into weight-bearing and grasping tools as early tetrapods took their first steps onto land.
Photography Tips
Place the bone flat against a neutral-colored background alongside a coin or ruler for scale, using soft, natural side-lighting to highlight the gentle curve of the shaft and the rounded contours of the ends.