Musculoskeletal Disorders. Sean Gallagher

Musculoskeletal Disorders - Sean Gallagher


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at several sites. (c and d) Hyaline cartilage in an epiphyseal plate (growth plate) of a radial bone. Low to higher power images are shown.

      Function

      The large amounts of hyaluronic acid and other components in hyaline cartilage help retain water in the extracellular matrix. As a consequence, this type of cartilage provides resilience and pliability and is well adapted to serve in a weight‐bearing joint, especially at points of movement. Hyaline cartilage also reduces friction and protects bony surfaces.

      Fibrocartilage

      Structure

      Fibrocartilage is located at the intervertebral discs between the vertebrae (Figure 3.15), pubic symphysis, and in the menisci of knees. Fibrocartilage is distinct from hyaline cartilage in composition and structure. Fibrocartilage has a higher dry weight of collagen and less water, making it tougher and less resilient than articular cartilage. Its collagen fibers are thick (and therefore visible) and densely deposited in the tissue. In fact, the collagen fibers are so tightly packed that there is little evidence of an extracellular matrix. The chondrocytes are scattered among the many bundles of collagenous fibers.

      Function

      The structure of fibrocartilage combines both strength and rigidity; therefore, it is key to the support and fusion of joints in which it is present. Fibrocartilage is an anisotropic material that exhibits different strength capacities depending on the direction of loading (Murphy, Black, & Hastings, 2016). For example, it has been shown that fibrocartilage is strong during tension occurring in parallel to the orientation of the collagen fibers, but weaker during shear loading (Mansour, 2009).

      Elastic Cartilage

      Structure

      Function

      The elastic materials in this type of cartilage give it elastic properties in addition to the resilience and pliability of its other hyaline cartilage components. Related to musculoskeletal tissue function, the elastic fibers in the ligamentum flava of the vertebra aid in the rebound of vertebrae from a flexed position to an upright position. Thus, elastic cartilage gives support and maintains the shape of its inclusionary structure. Unlike hyaline cartilage, the matrix of elastic cartilage does not calcify.

Photo depicts elastic cartilage.
Characteristic Description
Tissue type Dense mineralized connective tissue
Cells Main cell types: Osteoblasts, bone lining cells, osteocytes, osteoclasts, bone marrow–derived mesenchymal stem cellsAdditional cell types: Hematopoietic cells in marrow spaces
ECM Collagen type I (~70%), 25% water, inorganic minerals (e.g., calcium, phosphorus)
Subtypes Cortical bone (compact bone), trabecular (cancellous/spongy bone)
Function Strength, stability, lever at points of attachment, storage of minerals/lipids/nutrients, blood cell formation

      Bone Structure

      Cells


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