appendage

An anatomical appendage is any major bodily subdivision that extends or protrudes from the main body axis. In vertebrates, appendages include the paired limbs (arms, legs, wings, fins) and unpaired structures like the tail. In arthropods, appendages include legs, antennae, mouthparts, and wings.

Paired appendages occur bilaterally in symmetric positions — such as the four limbs of tetrapods or the pectoral and pelvic fins of fish. Unpaired appendages, like the tail or median fins of fish, occur along the body's midline. This distinction is fundamental in comparative anatomy.

Yes. The forelimbs of tetrapods — whether a human arm, a bat wing, a whale flipper, or a bird wing — are homologous appendages sharing the same basic bone pattern (humerus, radius/ulna, carpals, metacarpals, phalanges) derived from a common ancestor, modified through evolution for different functions.