To understand how muscles function when generating force and producing movement, we must look at their internal structure. A better understanding of what tissue types make up a muscle, the purpose of each, and the organization or architecture of a muscle also helps illuminate how bodywork may improve muscle function. This knowledge informs bodyworkers about what structures to target, how best to target those structures, and what exactly is occurring as specific techniques are applied.

The functional unit of a muscle is the motor unit. A motor unit is composed of a group of muscle cells and the single nerve that controls their collective activity. To function optimally, this tiny structure relies on ideal proximity between the nerve ending and muscle cells, as well as delivery of energy and metabolic chemicals to both nerve and muscle cells. Delivery requires adequate circulation and effective chemical exchange between the vessels of the circulatory system and individual nerve and muscle cells. Under specific chemical conditions, the motor units are activated and proteins within the muscle cell interact to produce force and generate movement.

Connective tissue wrappings support, protect, and separate the functioning units of a muscle, optimizing the chemical and electrical interactions between the nerve, muscle cells, and circulatory structures essential to muscle function. These layers collectively are referred to as myofascia. Individual muscle cells, called fibers, are each wrapped in a sheath of connective tissue called the endomysium (endo- means within). Many muscle fibers are grouped into bundles called fascicles, which are held together and encircled by a layer of connective tissue called the perimysium (peri- means around). Finally, these “bundles of bundles” are enveloped by the epimysium (epi- signifies a covering), a layer of connective tissue that surrounds individual muscles. All these connective tissue layers work together to help maximize cellular activity and transmit force while protecting the muscle fibers from damage during muscle contraction.

At either end of a muscle, the various layers of connective tissue converge to form a tendon that connects the muscle to bone. A seamless connection between the myofascia and the periosteum of bone forms a strong anchor and directional force transmitter between these structures and is fundamental to the system of levers that creates movement in the human body. The musculotendinous junction describes the point at which this connective tissue convergence begins while the portion of the muscle between tendons is called the muscle belly. Larger blood vessels and nerves are enclosed within the epimysium, and capillaries and nerve fiber endings are wrapped within the endomysium where they interact with individual muscle fibers.

Now we can visualize the layers of myofascia and the location of nerves and blood vessels within the architecture of a muscle. Remember, connective tissue has an inherent tendency to form bonds or connections that are influenced by use. This is a dynamic and responsive structure where internal bonds are broken to increase mobility and reinforced to enhance structural stability, and this process is occurring at all levels of the myofascia.

Excessive buildup of these myofascial connections are commonly referred to as adhesions and may limit the delivery of nutrients, removal of metabolic waste, and production of energy necessary for optimal muscle function at the cellular level.

Connective tissue also has the capability to change form from a liquid to a solid, depending on conditions—a property called thixotropy. Which state depends on several factors, including temperature, tension, and agitation. Bodyworkers commonly seek to influence both the thixotropic properties of connective tissue and the bonds formed between layers of myofascia to influence tissue quality and function. Connective tissue is prompted to become more pliable and fluid by increasing temperature through application of heat, applied friction, or active engagement of skeletal muscles. Agitation through jostling or vibration also effectively prompts a change from a solid to liquid state. The state of various layers of myofascia are also manipulated using prolonged application of tension common to techniques like myofascial release and passive range of motion. Myofascial adhesions that limit fluid flow within a muscle are targeted using techniques like petrissage, cross-fiber friction, and other myofascial release techniques at various depths.

takeaway: Myofascial layers can be manipulated through prolonged application of tension techniques like myofascial release and passive range of motion.