Fascia, a thin layer of fibrous connective tissue, is distributed throughout the body. It demarcates and forms a supportive covering over skeletal muscles, bones, blood vessels, and organs. There are three main types of facia— superficial fascia, deep fascia, and subserous fascia. These are all present at different depths in the body. Fascia reduces the friction and permits muscles, joints, and organs to easily slide against each other, facilitating movement of the body and preventing tearing of tissues. Additionally, fascia also adjusts to mechanical stress, regulates the shape of soft tissues, and eases muscle tension. Therefore, the fascial system is a continuum that senses and distributes tension among muscles and organs so that the body can move freely and function as a whole.

Fascia is strong and flexible owing to its layers of collagen fibers. It consists of a fluid matrix rich in hyaluronic acid, which lubricates fascia and permits it to stretch as the body moves. Trauma and inflammation can cause a reduction in hyaluronic acid that results in tightening of muscles and other tissues. This may cause pain and reduce mobility. Fascial disorders include plantar fasciitis (inflammation of plantar fascia under the soles of feet), Dupuytren's contracture(tightness in the fascia under the palms and fingers), frozen shoulder (a painful condition restricting shoulder movement), and hernias (excessive free movement of internal structures and organs due to defects in the fascia).