The periosteum is a thin layer of dense, irregular connective tissue membrane that covers the outer surface of a bone in all places except at joints. (The outer surface of bone at joints is covered with "articular cartilage", a type of hyaline cartilage.) As opposed to osseous tissue itself, periosteum has nociceptive nerve endings, making it very sensitive to manipulation. It also provides nourishment by providing the blood supply. Periosteum is attached to bone by strong collagenous fibers called Sharpey's fibres, which extend to the outer circumferential and interstitial lamellae.
Periosteum consists of an outer "fibrous layer" and inner "cambium layer". The fibrous layer contains fibroblasts while the cambium layer contains progenitor cells which develop into osteoblasts that are responsible for increasing the width of a long bone. (The length of a long bone is controlled by the epiphyseal plate.) After a bone fracture the progenitor cells develop into osteoblasts and chondroblasts which are essential to the healing process. Periosteum provides an attatchment for muscles and tendons.
Periosteum that covers the outer surface of the skull is known as "pericranium".
- Brighton, Carl T. and Robert M. Hunt (1997), "Early histologic and ultrastructural changes in microvessels of periosteal callus", Journal of Orthopaedic Trauma, 11 (4): 244-253
- Netter, Frank H. (1987), Musculoskeletal system: anatomy, physiology, and metabolic disorders, Summit, New Jersey: Ciba-Geigy Corporation