Fascia (făsh'ē-ə), pl. fas·ci·ae (făsh'ē-ē), adj. fascial (făsh'ē-əl) (from latin: a band) is the soft tissue component of the connective tissue system that permeates the human body. It interpenetrates and surrounds muscles, bones, organs, nerves, blood vessels and other structures. Fascia is an uninterrupted, three-dimensional web of tissue that extends from head to toe, from front to back, from interior to exterior. It is responsible for maintaining structural integrity; for providing support and protection; and acts as a shock absorber. Fascia has an essential role in hemodynamic and biochemical processes, and provides the matrix that allows for intercellular communication. Fascia functions as the body's first line of defense against pathogenic agents and infections. After injury, it is the fascia that creates an environment for tissue repair. 
Superficial fascia is found in the subcutis in most regions of the body, blending with the reticular layer of the dermis.  It is present on the face, over the upper portion of the sternocleidomastoid, at the nape of the neck, and overlying the sternum.  It is comprised mainly of loose areolar connective tissue and adipose and is the layer that primarily determines the shape of a body. In addition to its subcutaneous presence, this type of fascia surrounds organs and glands, neurovascular bundles, and is found at many other locations where it fills otherwise unoccupied space. It serves as a storage medium of fat and water; as a passageway for lymph, nerve and blood vessels; and as a protective padding to cushion and insulate. 
Deep fascia is the dense fibrous connective tissue that interpenetrates and surrounds the muscles, bones, nerves and blood vessels of the body. It provides connection and communication in the form of aponeuroses, ligaments, tendons, retinacula, joint capsules, and septa. The deep fasciae envelop all bone (periosteum and endosteum); cartilage (perichondrium), and blood vessels (tunica externa) and become specialized in muscles (epimysium, perimysium, and endomysium) and nerves (epineurium, perineurium, and endoneurium). The high density of collagen fibers is what gives the deep fascia its strength and integrity. The amount of elastin fibers determines how much extensibility and resiliancy it will have. 
Visceral Fascia suspends the organs within their cavities and wraps them in layers of connective tissue membranes. Each of the organs is covered in a double layer of fascia; these layers are separated by a thin serous membrane. The outermost wall of the organ is known as the parietal layer, whereas the skin of the organ is known as the visceral layer. The organs have specialized names for their visceral fasciae. In the brain, they are known as meninges; in the heart they are known as pericardia; in the lungs, they are known as pleura; and in the abdomen, they are known as peritonea. 
Fascia is a highly adaptable tissue. Due to its elastic property, superficial fascia can stretch to accommodate the deposition of adipose that accompanies both ordinary and prenatal weight gain. After pregnancy and weight loss, the superficial fascia slowly reverts to its original level of tension.
Visceral fascia is less extensible than superficial fascia. Due to its suspensory role of the organs, it needs to maintain its tone rather consistently. If it is too lax, it contributes to organ prolapse, yet if it is hypertonic, it restricts proper organ motility. 
Deep fascia is also less extensible than superficial fascia. It is essentially avascular, but is richly innervated with sensory receptors that report the presence of pain (nociceptors); change in movement (proprioceptors); change in pressure and vibration (mechanoreceptors); change in the chemical milieu (chemoreceptors); and fluctuation in temperature (thermoreceptors). ,  Deep fascia is able to respond to sensory input by contracting; by relaxing; or by adding, reducing, or changing its composition through the process of fascial remodeling. 
Deep fascia can contract. What happens during the fight-or-flight response is an example of rapid fascial contraction . In response to a real or imagined threat to the organism, the body responds with a temporary increase in the stiffness of the fascia. Bolstered with tensioned fascia, people are able to perform extraordinary feats of strength and speed under emergency conditions.  How fascia contracts is still not well understood, but appears to involve the activity of myofibroblasts. Myofibroblasts are fascial cells that are created as a response to mechanical stress. In a two step process, fibroblasts differentiate into proto-myofibroblasts that with continued mechanical stress, become differentiated myofibroblasts.  Fibroblasts cannot contract, but myofibroblasts are able to contract in a smooth muscle-like manner. 
The deep fascia can also relax. By monitoring changes in muscular tension, joint position, rate of movement, pressure, and vibration, mechanoreceptors in the deep fascia are capable of initiating relaxation. Deep fascia can relax rapidly in response to sudden muscular overload or rapid movements. Golgi tendon organs operate as a feedback mechanism by causing myofascial relaxation before muscle force becomes so great that tendons might be torn. Pacinian corpuscles sense changes in pressure and vibration to monitor the rate of acceleration of movement. They will intiate a sudden relaxatory response if movement happens too fast.  Deep fascia can also relax slowly as some mechanoreceptors are designed to report changes over a longer period of time. Unlike the Golgi tendon organs, Golgi receptors report joint position independent of muscle contraction. This helps the body to know where the bones are at any given moment. Ruffini endings respond to regular stretching and to slow sustained pressure. In addition to initiating fascial relaxation, they contribute to full-body relaxation by inhibiting sympathetic activity which slows down heart rate and respiration. 
When contraction persists, fascia will respond with the addition of new material. Fibroblasts secrete collagen and other proteins into the extracellular matrix where they bind to existing proteins, making the composition thicker and less extensible. Although this potentiates the tensile strength of the fascia, it can unfortunately restrict the very structures it aims to protect. The pathologies resulting from fascial restrictions range from a mild decrease in joint range of motion to severe fascial binding of muscles, nerves and blood vessels, as in compartment syndrome of the leg. However, if fascial contraction can be interrupted long enough, a reverse form of fascial remodeling occurs. The fascia will normalize its composition and tone and the extra material that was generated by prolonged contraction will be ingested by macrophages within the extracellular matrix. 
Like mechanoreceptors, chemoreceptors in deep fascia also have the ability to promote fascial relaxation. We tend to think of relaxation as a good thing, however fascia needs to maintain some degree of tension. This is especially true of ligaments. To maintain joint integrity, they need to provide adequate tension between bony surfaces. If a ligament is too lax, injury becomes more likely. Certain chemicals, including hormones, can influence the composition of the ligaments. An example of this is seen in the menstrual cycle, where hormones are secreted to create changes in the uterine and pelvic floor fascia. The hormones are not site-specific, however, and chemoreceptors in other ligaments of the body can be receptive to them as well. The ligaments of the knee may be one of the areas where this happens, as a significant association between the ovulatory phase of the menstrual cycle and an increased likelihood for an anterior cruciate ligament injury has been demonstrated. 
It has been suggested that manipulation of the fascia by acupuncture needles is responsible for the physical sensation of qi flowing along meridians in the body.
Arachnoid mater, Denticulate ligament, Dura mater, Endoneurium, Epineurium, Meninges, Nerve fascicle, Perineurium, Pia mater
Fasciae of the Ears
Annular stapedial ligament, Anterior auricular ligament, Anterior ligament of malleus, Lateral ligament of malleus, Posterior auricular ligament, Posterior ligament of incus, Superior auricular ligament, Superior ligament of incus, Superior ligament of malleus, Tectorial membrane (cochlea)
Fasciae of the Eyes
Medial palpebral ligament, Orbital fascia, Orbital septum, Zonular fibers
Annular ligaments of trachea, Central tendon of the diaphragm, Crus of diaphragm, Gastrophrenic ligament, Interarticular ligament, Lateral arcuate ligament, Left triangular ligament, Medial arcuate ligament, Median arcuate ligament, Phrenicocolic ligament, Pleura, Right triangular ligament, Suprapleural membrane
Anal fascia, Anococcygeal raphe, Cardinal ligament, External spermatic fascia, Broad ligament of the uterus, Cooper's ligaments, Cremasteric fascia, Duodenorenal ligament, Endopelvic part of the pelvic fascia, Fascia of Camper, Fascia of Colles, Fascia of Scarpa, Fundiform ligament, Inferior ligament of epididymis, Inferior pubic ligament, Internal spermatic fascia, Lateral pubovesical ligament, Lateral umbilical ligament, Medial pubovesical ligament, Medial umbilical ligament, Median umbilical ligament, Mesosalpinx, Ovarian ligament, Parametrium, Perineal body, Perineal membrane, Puboprostatic ligament, Pubovesical ligament, Reflected inguinal ligament, Renal capsule, Renal fascia, Round ligament of uterus, Superior fascia of the urogenital diaphragm, Superior ligament of epididymis, Suspensory ligament of the ovary, Suspensory ligament of the penis, Tunica albuginea (ovaries), Tunica albuginea (penis), Tunica albuginea (testicles)
Anterior longitudinal ligament, Aponeurosis of the Obliquus externus abdominis, Conjoint tendon, Costotransverse ligament, Costoxiphoid ligament, Fundiform ligament, Iliolumbar ligament, Interarticular ligament of the head of the rib, Interarticular sternocostal ligament, Intercrural fibers, Interspinal ligament, Intertransverse ligament, Lateral costotransverse ligament, Ligamenta flava, Linea alba, Linea semilunaris, Lumbocostal ligament, Posterior longitudinal ligament, Radiate ligament, Radiate sternocostal ligaments, Rectus sheath, Sacrospinous ligament, Superior costotransverse ligament, Supraspinous ligament, Tendinous intersection, Thoracolumbar fascia
Fasciae of the Muscles and Bones of the Pelvis
Anterior sacrococcygeal ligament, Anterior sacroiliac ligament, Crura of superficial inguinal ring, Deep crural arch, Deep inguinal ring, Diaphragmatic part of the pelvic fascia, Fascia of the Obturator internus, Fascia of the Piriformis, Gluteal aponeurosis, Iliac fascia, Iliolumbar ligament, Iliopectineal arch, Iliopectineal fascia, Inferior pubic ligament, Inguinal ligament, Intercrural fibers, Interfoveolar ligament, Interosseous sacroiliac ligament, Lacunar ligament, Obturator membrane, Pectineal ligament, Posterior sacrococcygeal ligament, Posterior sacroiliac ligament, Reflex inguinal ligament, Sacrotuberous ligament, Superficial inguinal ring, Superior pubic ligament, Tendinous arch, Transversalis fascia
Fasciae of the Muscles and Bones of the Lower Extremity
Achilles tendon, Annular ligament of femur, Annular ligaments of toes, Anterior cruciate ligament, Anterior ligament of head of fibula, Anterior ligament of the lateral malleolus, Anterior meniscofemoral ligament, Anterior talofibular ligament, Arcuate popliteal ligament, Articular capsule of the knee joint, Bifurcated ligament, Calcaneocuboid ligament, Calcaneofibular ligament, Calcaneonavicular ligament, Capsule of hip joint, Collateral ligament of interphalangeal articulations of foot, Collateral ligament of metatarsophalangeal articulations, Coronary ligament of the knee, Deep crural arch, Fascia lata, Fascia cribrosa, Femoral sheath, Fibular collateral ligament, Iliofemoral ligament, Iliotibial tract, Inferior extensor retinaculum of the foot, Inferior transverse ligament of the tibiofibular syndesmosis, Interosseous cuneometatarsal ligaments, Interosseous membrane of the leg, Ischiofemoral ligament, Laciniate ligament, Ligament of head of femur, Medial collateral ligament, Oblique popliteal ligament, Patellar ligament, Peroneal retinacula, Plantar fascia, Plantar calcaneocuboid ligament, Plantar calcaneonavicular ligament, Plantar fascia, Posterior cruciate ligament, Posterior ligament of head of fibula, Posterior ligament of the lateral malleolus, Posterior meniscofemoral ligament, Posterior talofibular ligament, Pubofemoral ligament, Round ligament of femur, Short plantar ligament, Spring ligament, Superior extensor retinaculum of foot, Tibial collateral ligament, Transverse acetabular ligament, Zona orbicularis
^ Paoletti, Serge (2006). The Fasciae: Anatomy, Dysfunction & Treatment. Seattle, WA: Eastland Press, 151-161. ISBN 0-939616-53-X.
^ Skandalakis, John E.; Skandalakis, P.N.; Skandalakis, L.J.; Skandalakis, J. (2002). Surgical Anatomy and Technique, 2nd Ed.. Atlanta, GA: Springer, 1-2. ISBN 0-38798-752-5.
^ Paoletti, Serge (2006). The Fasciae: Anatomy, Dysfunction & Treatment. Seattle, WA: Eastland Press, 23-24. ISBN 0-939616-53-X.
^ Hedley, Gil. (2005). The Integral Anatomy Series Vol. 1: Skin and Superficial fascia [DVD]. Integral Anatomy Productions. Retrieved on 2006-07-17.
^ Hedley, Gil. (2005). The Integral Anatomy Series Vol. 2: Deep Fascia and Muscle [DVD]. Integral Anatomy Productions. Retrieved on 2006-07-17.
^ Hedley, Gil. (2005). The Integral Anatomy Series Vol. 3: Cranial and Visceral Fasciae [DVD]. Integral Anatomy Productions. Retrieved on 2006-07-17.
^ Paoletti, Serge (2006). The Fasciae: Anatomy, Dysfunction & Treatment. Seattle, WA: Eastland Press, 146-147. ISBN 0-939616-53-X.
^ Rolf, Ida P. (1989). Rolfing. Rochester, VT: Healing Arts Press, 38. ISBN 0-89281-335-0.
^ Chaitow, Leon (1988). Soft Tissue Manipulation. Rochester, VT: Healing Arts Press, 26-28. ISBN 0-89281-276-1.
^ Schleip, R. (2003). "Fascial plasticity – a new neurobiological explanation: Part 1". Journal of Bodywork and Movement Therapies7 (1): 15-19. Elsevier.
^ Myers, Thomas W. (2002). Anatomy Trains. London, UK: Churchill Livingstone, 15. ISBN 0-443-06351-6.
^ Schleip, R.; Klingler W.; Lehmann-Horn, F. (2005). "Active fascial contractility: Fascia may be able to contract in a smooth muscle-like manner and thereby influence musculoskeletal dynamics". Medical Hypotheses65: 274. Elsevier.
^ Tomasek, J.; Gabbiani, G.; Hinz, B.; Chaponnier, C.; Brown, R. (2002). "Myofibroblasts and Mechanoregulation of Connective Tissue Remodelling". Molecular Cell Biology3: 350-352. Nature Publishing Group.
^ Schleip, R.; Klingler, W.; Lehmann-Horn, F. (2005). "Active fascial contractility: Fascia may be able to contract in a smooth muscle-like manner and thereby influence musculoskeletal dynamics". Medical Hypotheses65: 273-277. Elsevier.
^ Chaitow, Leon (1988). Soft Tissue Manipulation. Rochester, VT: Healing Arts Press, 26-27. ISBN 0-89281-276-1.
^ Schleip, R. (2003). "Fascial plasticity – a new neurobiological explanation: Part 1". Journal of Bodywork and Movement Therapies7 (1): 11-19. Elsevier.
^ Schleip, R. (2003). "Fascial plasticity – a new neurobiological explanation: Part 2". Journal of Bodywork and Movement Therapies7 (2): 104-116. Elsevier.
^ Paoletti, Serge (2006). The Fasciae: Anatomy, Dysfunction & Treatment. Seattle, WA: Eastland Press, 138, 147-149. ISBN 0-939616-53-X.
^ Wojtys, E.; Huston, L.; Lindenfeld, T.; Hewett, T.; Greenfield M.L. (1998). "Association Between the Menstrual Cycle and Anterior Cruciate Ligament Injuries in Female Athletes". American Journal of Sports Medicine26: 614-619. American Orthopaedic Society for Sports Medicine.
^ Heitz, N.; Eisenman, P.; Beck, C.; Walker, J. (1999). "Hormonal Changes Throughout the Menstrual Cycle and Increased Anterior Cruciate Ligament Laxity in Females". Journal of Athletic Training32 (2): 144-149. National Athletic Trainers Association.
^ Kimura M, Tohya K, Kuroiwa K, Oda H, Gorawski EC, Hua ZX, Toda S, Ohnishi M, Noguchi E. “Electron microscopical and immunohistochemical studies on the induction of "Qi" employing needling manipulation.” Am J Chin Med. 1992;20(1):25-35.
^ Dorlands Medical Dictionary - aponeuroses. Merck Source.
^ Dorlands Medical Dictionary - fasciae. Merck Source.
^ Dorlands Medical Dictionary - ligaments. Merck Source.
^ Dorlands Medical Dictionary - membranes. Merck Source.
^ Dorlands Medical Dictionary - tendons. Merck Source.
^ Fasciae and Aponeuroses - Organized by Region. Department of Anatomy, University of Arkansas for Medical Sciences.
^ Fascia of the Head and Neck. Department of Gross Anatomy at Tufts University.
^ Viscera and Fascia Tables. The University of Michigan - Medical Gross Anatomy.