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The periosteum is a membrane that covers the outer surface of all bones, [1] except at the articular surfaces (i.e. the parts within a joint space) of long bones. (At the joints of long bones the bone's outer surface is lined with "articular cartilage", a type of hyaline cartilage .)
This is covered by a membrane of connective tissue called the periosteum. Beneath the cortical bone layer is a layer of spongy cancellous bone. Inside this is the medullary cavity which has an inner core of bone marrow, it contains nutrients and help in formation of cells, made up of yellow marrow in the adult and red marrow in the child.
This newly formed bone can be called "periosteal bone" as it originates from the transformed periosteum. However, considering its developmental pathway, it could be classified as "intramembranous bone". [8] After the formation of the periosteum, chondrocytes in the primary center of ossification begin to grow (hypertrophy).
Examples of periosteal reactive bone in selected specimens of Triceratops. A periosteal reaction can result from a large number of causes, including injury and chronic irritation due to a medical condition such as hypertrophic osteopathy, bone healing in response to fracture, chronic stress injuries, subperiosteal hematomas, osteomyelitis, and cancer of the bone.
Mucoperiosteum is a compound structure consisting of mucous membrane and underlying periosteum. It includes epithelium and lamina propria, but attaches directly to the periosteum of underlying bone without the usual submucosa. It consists of loose fatty or glandular tissues; with blood vessels & nerve fibres that supply the mucosa.
The periosteum is formed around the trabeculae by differentiating mesenchymal cells. The primary center of ossification is the area where bone growth occurs between the periosteum and the bone. Osteogenic cells that originate from the periosteum increase appositional growth and a bone collar is formed.
The periosteum is one source of precursor cells that develop into chondroblasts and osteoblasts that are essential to the healing of bone. Other sources of precursor cells are the bone marrow (when present), endosteum , small blood vessels , and fibroblasts .
The deep fasciae envelop all bone (periosteum and endosteum); cartilage (perichondrium), and blood vessels (tunica externa) and become specialized in muscles (epimysium, perimysium, and endomysium) and nerves (epineurium, perineurium, and endoneurium). The high density of collagen fibers gives the deep fascia its strength and integrity.