Neurovascular Injury Displacement of fracture fragments or bone ends at a dislocated joint carry the risk of producing compression or laceration of adjacent vessels and nerves (see Plate 9-1 ). Critical neurovascular structures (e.g., the brachial plexus) lie deep in the limb, close to the skeleton, which protects them from injuries. A fracture or dislocation makes nerves or vessels vulnerable to injury from sharp bone fragments…

Septic Joint Septic Bursitis The human body contains more than 150 bursae, which are sacs or potential spaces lined with a synovial membrane and containing synovial fluid. Bursae, located in the subcutaneous tissue over bony prominences, permit virtually friction-free movement of the skin over these prominences, minimizing irritation. With excessive irritation or use of a joint, a bursa can become inflamed and swollen as more synovial…

Injury to Soft Tissue Three basic mechanisms cause soft tissue injuries: blunt trauma, crushing injury, and penetrating trauma. Blunt and crushing injuries are called closed injuries because they do not penetrate the overlying skin. Penetrating (open) injuries violate the protective skin layer, contaminating the wound and thus producing open injuries. Closed Soft Tissue Injuries Closed injuries are characterized by variable degrees of damage to skin and…

Initial Evaluation and Staging of Musculoskeletal Tumors An understanding of the tumors of the musculoskeletal system requires a thorough knowledge of clinical presentation, natural history, staging characteristics, histopathology, and response to treatment of these tumors. Common bone tumors include myeloma, lymphoma, and metastases from primary breast, lung, kidney, thyroid, and prostate cancers; and these are, in fact, the most common malignant bone lesions in patients older…

Rheumatic Diseases The term rheumatic disease refers to any illness characterized by pain and stiffness in or around the joints. These diseases are divided into two main groups: disorders that involve the joints primarily (the different forms of arthritis) and disorders that, although not directly affecting the joints, involve connective tissue structures around the joints (the periarticular disorders, or nonarticular rheumatism). The many types of arthritis…

Dwarfism—Overview and Achondroplasia Classification Although hereditary disorders of the skeleton are relatively rare, they attract a great deal of interest. Many of these disorders are associated with short stature, or dwarfism. Dwarfism can be either proportionate or disproportionate. Symmetric shortness of the trunk and limbs is common with proportionate dwarfism. Disproportionate dwarfism, in which either the trunk or limbs are more affected than the other, is…

Parathyroid Hormone The parathyroid gland regulates the calcium in the extracellular fluid by sensing small changes in calcium levels and rapidly modifying the secretion of parathyroid hormone (PTH). With a fall in the calcium level, PTH secretion is increased and, in turn, leads to increased calcium concentration and suppressed PTH secretion, thus completing a feedback loop. PTH raises the calcium level by promoting the entry of…

Structural Organization of Skeletal Muscle The principal function of skeletal muscles is to move the limbs, trunk, head, respiratory apparatus, and eyes. Most skeletal muscles are under voluntary control. They are composed of long multinucleated cells called muscle fibers, which are derived by fusion of many embryonic cells called myoblasts to form myotubes during development. The ends of the muscle fibers insert into tendons that, in…

Development of Musculoskeletal System Evolution The development of the human musculoskeletal system is an interesting demonstration of ontogeny recapitulating phylogeny. The genetic code that guides the continually changing body plan of the developing human results in a résumé of body plans of the various forms of our vertebrate ancestors from which fish, amphibians, reptiles, and mammals evolved. In their adult state, a number of living animals…