Back

The back (or dorsal region) is the upper or posterior part of the trunk, extending from the base of the neck to the tail, and bordered ventrally by the abdominal cavity and laterally by the flanks.

The back forms the main supporting axis of the body, houses and protects the spinal cord, and serves as an attachment point for numerous muscles essential for locomotion, posture, and respiration. This region is primarily composed of the vertebral column (including the thoracic, lumbar, and sacral vertebrae), the dorsal muscles, and the associated neural and vascular structures.

Across species, the fundamental structure of the back is conserved, but certain variations exist. For example, the backs of carnivores (dogs, cats) are generally more flexible, allowing a wide range of motion, whereas those of large herbivores (horses, ruminants) are more robust and rigid, adapted to weight-bearing and to transmitting force during locomotion.