Curvature of spine

The vertebral column, also known as the backbone, spine, or spinal column, is the core part of the axial skeleton in vertebrate animals. The vertebral column is the defining characteristic of vertebrate endoskeleton in which the notochord (a flexible collagen-wrapped glycoprotein rod) found in all chordates has been replaced by a segmented series of mineralized irregular bones (or sometimes, cartilages) called vertebrae, separated by fibrocartilaginous intervertebral discs (the center of which is a notochord remnant). The dorsal portion of the vertebral column houses the spinal canal, a cavity formed by alignment of the neural arches that encloses and protects the spinal cord.

There are around 50,000 species of animals that have a vertebral column. The human vertebral column is one of the most-studied examples, as the general structure of human vertebrae is fairly typical (homologous) of that found in other mammals, reptiles and birds. The shape of the vertebral body does, however, vary somewhat between different groups of living species.

Individual vertebrae are named according to their corresponding body region (neck, thorax, abdomen, pelvis or tail). In clinical medicine, features on vertebrae (particularly the spinous process) can be used as surface landmarks to guide medical procedures such as lumbar punctures and spinal anesthesia. There are also many different spinal diseases in humans that can affect both the bony vertebrae and the intervertebral discs, with kyphosis/scoliosis, ankylosing spondylitis, degenerative discs and spina bifida being recognizable examples.

Source: Wikipedia