By Anatomist90 (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
For a long time the fascial network surrounding all the body's major structures was largely ignored. Usually discarded without any examination when exploring cadavers, the importance of the fascia was not recognised. In recent decades the bodywork field has began awakening to the profound significance of this fascinating structure.
The subcutaneous layer of connective tissue
Subcutaneous or hypoderm comes from Latin and means ‘under the skin’. Subcutaneous tissue, hypodermis and superficial fascia are terms used interchangeably for the layer of connective tissue that underlies the skin. Some anatomy and physiology sources consider it the deepest layer of the skin.
It is mainly composed of loose connective tissue and adipose (fat) tissue and some and has a dual function. It serves as an energy reservoir and an insulator preventing heat loss from the body. The adipose tissue also protects the underlying tissues by acting as a shock absorber.
The number and distribution of adipocytes (fat cells) vary depending on age, gender, and location in the body. The size of the fat cells is largely determined by the nutritional status of the individual – i.e. what and how much they eat. “The fat you eat is the fat you wear” as Dr McDougall says, is a helpful reminder.
The subcutaneous layer also connects the dermis to the bones and muscles. Further, it provides support to the blood vessels, lymphatic vessels, nerves, and glands that pass through it reaching the dermis.
In this region, there are also fibrous bands that anchor the skin to the deep fascia. Collagen and elastin fibres connect the subcutaneous tissue to the dermis. The dermis is connected to the lymphatic system thanks to lymphatic vessels situated here. Nerve endings connect the nervous system with the dermis in the subcutaneous layer. Blood vessels act as the connecting link with the circulatory system. The superficial fascia turns into subcutaneous synovial bursae, especially over bony prominences. Sweat glands, mammary glands, mast cells, hair follicle roots, panniculus carnosus, Ruffini and Pacinian corpuscles are also situated here.
‘Connective tissue techniques’ is an umbrella term encompassing interventions aimed at affecting the connective tissue.
The muscle fascia and its function
Between the fatty layer of the subcutaneous tissue, there is a thin layer wrapping the body known as the deep or muscle fascia. It is a tough layer of connective tissue. It wraps and surrounds the muscles and attaches to subcutaneous bony prominences by fusing with the outer layer of the bone.
The deep fascia can be seen as a self-contained three-dimensional structure which envelops muscles, organs, nerves and cells in the body. It serves the dual purpose of being a filter and a barrier for body fluids in and around body structures. The condition and hydration of the fascia have a significant influence on the health of the tissues it wraps around.
In the fascia, there is a high saturation of mechanoreceptors which transmit sensory information to the central nervous system. Thanks to the myofibroblasts inside, the fascia can contract on an autonomic level. These facts can provide an explanation of muscle tone related to the autonomic fascial responses rather than muscle fibre contraction.
Muscles can be fully or partly inserted into the fascia. Gluteus maximus, for example, inserts into the thick fascia of the iliotibial tract in the lateral part of the leg. Often sheets of deep fascia would pass between groups of muscles before blending with the outer covering (periosteum) of the bones beneath.
Over joints, the deep fascia holds tendons in place by forming tough sheets. The flexor retinacula in the anterior joint are one such example.
The deep fascia is also essential for blood circulation. Gravity pulls blood down in some parts of the body. The deep fascia prevents muscle mass in these areas through its increased toughness in these areas.
Fascia and posture
A part of the fascia is very intimately related to the muscular system and has high significance for bodyworkers. This is the myofascia. It is composed of a polysaccharide complex, called ground substance, contained within elastin and collagen fibres. The ability of elastin to stretch and the tensile strength of collagen combine to give great physical potential to the fascia.
Through years of evolution, fascial fibres gradually adapted to the demands placed on the human body. This resulted in the upright posture of (most) homo sapiens we are familiar with today. Movement is created by the contractile units (muscles) located in these pockets of connective tissue.
This all-present and all-encompassing wrapping around the structures of the body provides an integrated view as opposed to seeing muscles, bones, tendons, and ligaments as separate structures. These conceptual distinctions merge into the reality of the fascial network wrapping and keeping the whole human body a single unit. This holistic perspective also makes the interconnectedness of all muscles more apparent. This, in turn, makes it clear why an imbalance or a malfunction in one part of the body can have systemic effects felt throughout the whole.
Another important property of myofascial is its great adaptability. For example, in response to prolonged periods of immobility it starts to form tiny fibrous bonds with adjacent tissues. These melt away if activity resumes shortly after, but if left for a long time they begin to thicken and sculpt the body in this particular position. This mechanism provides the basis for the formation of postural deviations in response to habitation. Often when speaking about short or tight muscle, it is, in reality, the surrounding fascia that is keeping the underlying muscular pockets in this shape and position.
While stretching can be helpful in lengthening the muscles, it has little effect on the surrounding fascia. This is why manual techniques are a fundamental component of effective postural remediation approaches.