Musculoskeletal Key

Regardless of its histologic type, connective tissue is made up of two components, cells and extracellular matrix. Fibroblasts (which synthesize collagen), fat cells, fixed macrophages, mast cells, plasma cells, and…

On gross examination, the synovial surface appears pale pink and shiny. Although some folds can be seen with the naked eye, the characteristic villi that increase the effective surface area…

To make the situation even more complex, aggrecans form aggregates with two other matrix components—hyaluronan and link proteins. This aggregate consists of a variable number of proteoglycan monomers, depending on…

Like members of most families, the collagens share certain similarities but also possess characteristic differences. To date, 28 types of collagen macromolecules have been identified. The most abundant, type I…

In actively growing, or remodeling, trabecular bone, the direction of deposition can be determined by a row of osteoblasts on one border of the trabecula (see Plate 2-23). The deposition…

Cortical bone is remodeled by on the periosteal, endosteal, and haversian canal surfaces. These surfaces are called bone envelopes, or remodeling bays. The periosteal surface is responsible for the growth…

Mature lamellar bone has the same chemical composition and material properties throughout the skeleton, regardless of its mechanism of formation—intramembranous or endochondral—or its structural organization—cortical (compact) or trabecular bone. Skeletal…

The osteoblast, or bone-forming cell, is approximately 20 µm in diameter and contains a single eccentric nucleus. Under the direction of RUNX2 and Osterix transcription factors, osteoblasts arise from osteoprogenitor…

Metaphysis. The three functions of the metaphysis are vascular invasion of the transverse septa at the bottom of the cartilaginous portion of the growth plate, bone formation, and bone remodeling…

Regardless of its specialized function, all cartilage consists of cells—chondrocytes and chondroblasts. These cells synthesize and deposit around them an elaborate matrix of macromolecules that are some of the largest…