G., Schwab, T., & Oxland, T. R. (2007). Cyclic loading causes faster rupture and strain rate than static loading in medial collateral ligament at high stress. Clinical Biomechanics, 22, 932–940.194 Treaster, D., & Burr, D. (2004). Gender differences in prevalence of upper extremity musculoskeletal disorders. Ergonomics, 47, 495–526.
195 Van der Windt, D., Thomas, E., & Pope, D. (2000). Occupational risk factors for shoulder pain: A systematic review. Occupational and Environmental Medicine, 57, 433–442.
196 van Kampen, D., Berg, T., Woude, H., Castelein, R., Scholtes, V., Terwee, C., & Willems, W. (2014). The diagnostic value of the combination of patient characteristics, history, and clinical shoulder tests for the diagnosis of rotator cuff tear. Journal of Orthopaedic Surgery Research, 9, 40.
197 van Rijn, R. M., Huisstede, B. M., Koes, B. W., & Burdorf, A. (2009). Associations between work‐related factors and specific disorders at the elbow: A systematic literature review. Rheumatology (Oxford), 48(5), 528–536. https://doi.org/10.1093/rheumatology/kep013
198 Vaquero‐Picado, A., Barco, R., & Antuña, S. (2017). Lateral epicondylitis of the elbow. EFORT Open Reviews, 1, 391–397.
199 Vernon‐Roberts, B., & Pirie, C. (1977). Degenerative changes in the intervertebral discs of the lumbar spine and their sequelae. Rheumatology Rehabilitation, 16, 13–21.
200 Viikari‐Juntura, E., & Silverstein, B. (1999). Role of physical load factors in carpal tunnel syndrome. Scandinavian Journal of Work, Environment & Health, 25, 163–185.
201 Visser, B., & van Dieen, J. H. (2006). Pathophysiology of upper extremity muscle disorders. Journal of Electromyography and Kinesiology, 16(1), 1–16. https://doi.org/10.1016/j.jelekin.2005.06.005
202 Waddell, G. (1987). Volvo award in clinical sciences: A new clinical model for the treatment of low‐back pain. Spine, 12, 632–644.
203 Walsh, T., Delahunt, E., & McCarthy, P. (2011). Effects of taping on thumb alignment and force application during PA mobilisations. Manual Therapy, 16, 264–269.
204 Wolf, J., Sturdivant, R., & Owens, B. (2009). Incidence of de Quervain’s tenosynovitis in a young, active population. Journal of Hand Surgery, 34A, 112–115.
205 Wolf, J. M., Mountcastle S., Burks, R., Sturdivant, R. X., & Owens, B. D. (2010). Epidemiology of lateral and medial epicondylitis in a military population. Military Medicine, 175, 336–339.
206 Yang, C., Leitkam, S., & Cote, J. N. (2019). Effects of different fatigue locations on upper body kinematics and inter‐joint coordination in a repetitive pointing task. PLoS One, 14(12), 0227247. https://doi.org/10.1371/journal.pone.0227247
207 Yoshii, Y., Zhao, C., Henderson, J., Zhao, K. D., An, K. N., & Amadio, P. C. (2011). Velocity‐dependent changes in the relative motion of the subsynovial connective tissue in the human carpal tunnel. Journal of Orthopaedic Research, 29, 62–66.
208 Yoshii, Y., Zhao, C., Zhao, K. D., Zobitz, M. E., An, K. N., & Amadio, P. C. (2008). The effect of wrist position on the relative motion of tendon, nerve, and subsynovial connective tissue within the carpal tunnel in a human cadaver model. Journal of Orthopaedic Research, 26, 1153–1158.
209 Zajac, A., Chalimoniuk, M., Maszczyk, A., Golas, A., & Lngfort, J. (2015). Central and Peripheral Fatigue During Resistance Exercise. A Critical Review. Journal of Human Kinetics, 49, 159–169. https://doi.org/10.1515/hukin‐2015‐0118
210 Zhang, Y. C. (2016). Intervertebral disc cells produce interleukins found in patients with back pain. American Journal of Physical Medicine & Rehabilitation/Association of Academic Physiatrists, 95(6), 407.
211 Zugel, M., Maganaris, C. N., Wilke, J., Jurkat‐Rott, K., Klingler, W., Wearing, S. C., & Hodges, P. W. (2018). Fascial tissue research in sports medicine: From molecules to tissue adaptation, injury and diagnostics: Consensus statement. British Journal of Sports Medicine, 52(23), 1497. https://doi.org/10.1136/bjsports‐2018‐099308
3 Structure and Function of the Musculoskeletal System
A Systems View of the Musculoskeletal System
The musculoskeletal system is composed of a variety of specialized forms of tissues, including skeletal muscles, tendons, bones, joints, ligaments, and associated connective tissues. It also includes the nerves and blood vessels that bring innervation and blood supply to these structures. These tissues work together as a system, with skeletal muscles contracting as a result of nervous impulses leading to movement through force exertion on tendons, which then pull on bones. Most muscles cross one or more joints (producing movement in the joints that they cross) before attaching to the articulating bones that form a joint. With muscle contraction, one articulating bone is drawn toward the other. One bone is typically held in its original position, because other muscles stabilize it or contract in the opposing direction, or because the structure of the bone or joint makes it less movable. Ligaments provide stability to these joints. In this chapter, we will discuss the basic structure and function of each of these tissues, except for the basic structure and function nerves, which will be discussed in Chapter 4. Repair properties of each of these tissues will be discussed in Chapter 11.
Connective Tissues: General Overview
Connective tissues are the most abundant tissues in the body. They envelop, protect, support, and separate structures as well as bind structures together. Connective tissues also act as a cushion between tissues, provide a pathway for nerves and blood vessels into and out of individual tissues, and more. Most connective tissues have a rich nerve supply and blood supply (except for cartilage which is aneural and avascular, and tendons which have a scanty blood supply). Special connective tissue types include cartilage, osseous (bone), and vascular (blood). The matrixes of these connective tissues differ, with some being fluid (blood), semifluid, gelatinous, fibrous (tendon), or calcified (bone). In cartilage, for example, the matrix is firm but pliable, while in bone, the matrix is considerably harder but not pliable.
General Connective Tissue Structure
Cells
Fibroblasts are common support cells in connective tissues. They are mesenchymal pluripotent cells with great heterogeneity in their subtypes. Fibroblasts are key producers of collagen and are heavily involved in the continuous slow turnover of a tissue’s extracellular matrix. When exposed to mechanical or physiological stress, fibroblasts adapt to their environment and have the ability to respond to and send local signals (e.g., cytokines and growth factors) (Dick, Miao, & Limaiem, 2020). Fibroblasts can also transform their phenotype into several other cell types for wound healing and replacement of damaged tissue (Dick et al., 2020). Other types of cells within connective tissues include adipocytes, macrophages (phagocytic immune cells), and plasma cells (cells that give rise to antibodies for immune defense). There are also mast cells that produce histamine and serotonin (chemicals that dilate small blood vessels) and heparin (an anticoagulant).
