Exploration for an infant means discovering anything about that environment. If that infant needs an opportunity to be brought to them, that's okay. Let an infant explore through their senses, whether it's touch, or smell, or taste, or sight, or hearing.
The spine is made up of many individual bones called vertebrae joined together by muscles and ligaments. Flat, soft discs separate and cushion the vertebrae from rubbing against each other. Because the vertebrae are separate, the spine is flexible and can bend. Together the vertebrae, discs, muscles, and ligaments make up the vertebral column or spine.