• coordinating element for motor units (grouped together in myofascial units)

• uniting element between unidirectional myofascial units (myofascial sequences)

• connecting element between body joints via myofascial expansions and retinacula (myofascial spirals).

• muscular fiber insertions directly onto deep fascia (Stecco et al. 2007a)

• fiber distribution according to precise motor directions (Stecco et al. 2008a, 2009a)

• myotendinous expansions that link adjacent segments (Stecco et al. 2009b).

• the superficial fascia, for its influence on lymphatic and venous return mechanisms

• the internal fasciae, for its influence on visceral dysfunctions (Stecco in press).

The myofascial unit

Each myofascial unit (MFU) comprises monoarticular and biarticular muscular fibers, the fascial structures, bones, nerve terminations and the specific portion of a joint involved in moving a body segment in a specific direction. In other words, each MFU is a functional unit composed of three elements that work in unison:

A significant characteristic of each MFU is the presence of both monoarticular and biarticular muscular fibers. The monoarticular fibers in each MFU are generally deeper fibers, specialized in moving a joint on one plane, and these fibers could be involved in the interplay between agonists and antagonists. In almost every MFU, a number of monoarticular fibers insert onto the intermuscular septum that separates two antagonist MFUs on the same plane. Whenever the agonist MFU is activated, traction exerted on the intermuscular septum could cause tension in the antagonist MFU, contributing to simultaneous adaptation, according to the inclination of the fibers and the segment involved. Recent studies of agonist and antagonist interaction by Huijing (2009) support this hypothesis.

The biarticular fibers in each MFU could intervene in synchronizing the activity of two in-series MFUs, modifying the position of the proximal segment in relation to movements of the distal segment, or vice versa, when necessary. At the same time, the monoarticular fibers of the respective MFUs could provide added stability for joints as they move.

Different studies evidence the role of monoarticular and biarticular muscle fibers in multiple joint movements (Savelberg & Meijer 2003; Kurtzer et al. 2006).

Within each MFU, some muscle fibers also insert directly onto the overlying fascia. These insertions could contribute to the maintenance of a basal tension of the fascia, and guarantee that fascia is stretched in a specific direction each time these muscle fibers contract (Stecco et al. 2008a, 2009b).

Within each MFU, two specific points can be identified (Fig. 7.7.1):

Evidence exists regarding reduced coordination of motor units in the presence of joint pain (Mellor & Hodges 2005), although the mechanism is unknown. The Fascial Manipulation model suggests a new neurophysiological basis for the coordinating role of the CC. During any movement, motor units are activated, causing muscle fibers to contract according to the degree and direction of required joint movement. Muscle spindle capsules, embedded between muscle fibers, are continuous with surrounding endomysium; therefore, when gamma fiber stimulation causes intrafusal spindle fibers to contract, a minimal stretch is propagated throughout the entire fascial continuum, including the fascia at the CC. If the fascia at the CC is elastic, then it will adapt to this stretch, permitting muscle spindles to contract normally, correct activation of alpha motor fibers, and subsequent muscular contraction to proceed smoothly. If fascia at the CC is not elastic, the muscle spindle contraction could interfere with motor unit activation. Incongruent motor unit activation would then result in uncoordinated movement, perceived at the CP either as joint instability or as pain (Pedrelli et al. 2009a).

For each body segment, six MFUs have been identified and each one is specific for one direction. This is also true for those joints that have limited movement on some planes (e.g., frontal plane for the knee or elbow) because these joints always have muscular and fascial components that act as stabilizers on those planes.

Each MFU is located on one of the three spatial planes. The MFUs associated with the movement of antemotion² (AN) are located in the anterior region of the limbs and trunk while the MFUs associated with retromotion³ (RE) are located in the posterior region. The MFUs associated with lateromotion (LA), movement away from the midline, are all located in the lateral region of the limbs and trunk, and those MFUs associated with mediomotion (ME), movement towards the midline, are located in the medial region. The MFUs associated with extrarotation (ER) are located in the retrolateral region of the limbs and trunk, and those associated with intrarotation (IR) in the anterolateral region (Fig. 7.7.2). Each MFU is named according to the segment it moves and the direction in which it moves that segment. There are 14 body segments and 6 directions, making a total of 84 CC and 84 CP (Fig. 7.7.3).

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