endosteum

1. (biology) A membranous vascular layer of cells which line the medullary cavity of a bone; an internal periosteum.Examples: "Hyaline cartilage is insensitive, and radiographic changes imputed to it can have no bearing on pain from it unless it is so worn away that the endosteums of the articulating bones are rubbing on each other."; "The cortical and trabecular endosteums are the inner linings of bone. The osteonal endosteum lines the osteonal canals […] and is the internal lining of bone. It is continuous with the periosteal and cortical endosteums."; "Periosteum and endosteum are connective tissue sheaths of bone. […] The endosteum is a less well-defined layer of connective tissue and osteogenic cells applied to the wall of a bony cavity. / a. The endosteum lies between the bone tissue and the bone marrow. / b. Unlike periosteum, endosteum lacks a distinct fibrous layer."