Endosteum lines the inner surface of the medullary cavity of all long bones.

The fibrous layer is of dense irregular connective tissue, containing fibroblasts, while the cambium layer is highly cellular containing progenitor cells that develop into osteoblasts.

After a bone fracture, the progenitor cells develop into osteoblasts and chondroblasts, which are essential to the healing process.

[4] As opposed to osseous tissue, the periosteum has nociceptors, sensory neurons that make it very sensitive to manipulation.

The periosteum that covers the outer surface of the bones of the skull is known as the pericranium, except when in reference to the layers of the scalp.