Bony Anatomy and Landmarks Anteriorly, the contour of the biceps muscle is seen starting in the upper arm and extending distally into the cubital fossa, which is the inverted triangular depression on the anterior aspect of the elbow. The flexion crease along the anterior elbow is in line with the medial and lateral epicondyles and is 1 to 2 cm proximal to the joint line when…

Bones and Joints of Shoulder The function of the upper extremity is highly dependent on correlated motion in the four articulations of the shoulder. These include the glenohumeral joint, the acromioclavicular joint, the sternoclavicular joint, and the scapulothoracic articulation. The glenohumeral joint has minimal bony constraints, thus allowing for an impressive degree of motion. Scapula Ossification centers of the scapula begin to form during the eighth…

Anatomy of the Ankle and Foot Tendon Sheaths at Ankle The extrinsic tendons of the foot originate as muscles in the leg, and as the tendons cross the ankle they must change their orientation. The retinaculum and the corresponding bony anatomy account for the pulley system that allows this to occur and to generate a mechanical advantage for transmission of force. The retinaculum also prevents bowstringing…

Compartments of Leg Fasciae and Compartments The fascia lata of the thigh continues into the leg, where it is designated as the crural fascia (see Plate 4-2 ). At the knee, the fascia has many attachments—the patella, patellar ligament, tibial tuberosity, condyles of the tibia, and head of the fibula—that reinforce the medial and lateral patellar retinacula. The fascia is strengthened by expansions of the tendons…

Anatomy of the Knee Knee Joint The knee is primarily a hinge joint that permits flexion and extension. In flexion, there is sufficient looseness to allow a small amount of voluntary rotation; in full extension, some terminal medial rotation of the femur (conjunct rotation) achieves the close-packed position. The condyles of the femur provide larger surfaces than those of the tibial condyles, and there is a…

Superficial Veins and Cutaneous Nerves Superficial Veins Certain prominent veins, unaccompanied by arteries, are found in the subcutaneous tissue of the lower limb (see Plate 2-1 ). The principal ones are the greater and lesser saphenous veins, which arise in the venous radicles in the feet and toes. Dorsal digital veins lie along the dorsal margins of each digit, uniting at the webs of the toes…

Vertebral Column The vertebral column is built from individual units of alternating bony vertebrae and fibrocartilaginous discs. These units are intimately connected by strong ligaments and supported by paraspinal muscles with tendinous attachments to the spine. The individual bony elements and ligaments are described in Plates 1-9 to 1-18 . There are 33 vertebrae (7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal), although…

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…