The periosteum is a dense layer of connective tissue that covers the outer surface of bones, except at the surfaces of joints. It plays a crucial role in bone health by providing a protective layer and serving as an attachment point for muscles and tendons. The periosteum contains blood vessels and nerves, which help nourish the bone and facilitate healing. This membrane has two layers: the outer fibrous layer, which provides strength and support, and the inner cambium layer, which contains cells that are important for bone growth and repair. The periosteum is essential for maintaining the integrity of the skeletal system and supporting overall mobility.