Posture and movement, straight and crossed muscle chains. It is important to note that the chains are made up of muscles and fasciae (that is why their full name is myofascial chains) and it must be borne in mind that those that cross from one side to the other of the axis of the body are the fasciae, which give continuity, and not the muscles, which are arranged symmetrically on either side of our axis.
Straight chains have a primarily postural and self-growing role in standing. Analyzing them as an antigravity system, they operate by structuring and distributing the energy of muscular work. The thoracolumbar, diaphragmatic, abdominal, and perineal fibrous centers function as convergence points for muscle contractions or tensor support areas for eccentric contractions.
Cross chains, on the other hand, have a movement function. In fact, in our evolution, we can progressively incorporate and "detach" ourselves from the ground thanks to the action of our straight chains and the control of our anti-gravity system, while any displacement, from the exploration that the head does to the sides or the scope of objects with the hands, up to the march on the feet, depends on the action of our crossed chains.
While the straight chains configure us in a sagittal plane, the crossed ones allow us the diagonals and integrate us into the three-dimensional world.
Due to their primary function of movement, the muscles that form these dynamic chains have a predominance of phasic fibers, making them paler than those with tonic activity and with a much greater range of contractility or shortening.
In the trunk, cross chains allow torsions whose axes go from one shoulder to the opposite hip. The crossing of these axes is at the level of the third lumbar vertebra (L3) behind and the navel in front. The arrangement of the muscle fibers is oblique, with a continuity that “connects” the hemithorax on one side with the hemipelvis on the other, that is, the two halves of the shoulder girdle with the two opposite halves of the pelvic girdle.
These chains are in front and behind.
The previous ones include the fibers that are directed on these crossed axes: right oblique minor, major left, superficial intercostals left, pectorals left. and serrato mayor izq. The other, to the same muscles on the opposite side.
The posterior ones include the iliolumbar diagonal fibers of the right lumbar square, the left ribs, the deep left intercostals and the left lower serratus. The other, ditto on the opposite side.
This action of spiraling the torso is completed and complemented by the mobility of the scapular and pelvic girdles, for the rotation of upper and lower limbs. In these movements, the muscles that mobilize scapulae, shoulders, pelvis and hips are involved.
Due to their arrangement, and because they work in conjunction with straight chains, as fastening elements, the action of the anterior crossed chains is to bring the upper quadrant of one side forward to the lower quadrant of the opposite side, associating an anterior flexion of the winding . Meanwhile, the posterior crossed chains bring the opposite quadrants from behind, generating an extension or unfolding of the column.
It is worth noting the existence of two planes of muscle fibers, which intersect their directions:
The greater oblique has superficial fibers, which go from outside and above to the midline and below, while the deeper, lesser oblique has fibers from the outside and down to above and inside (that is, towards the midline).
The superficial intercostals are diagonal up and back, and the deep incostals are up and forward.
Lumbar squares have deep fibers from below and outside, up and in, and superficial fibers from below and inside, up and out.
This mesh of muscle fibers has continuity on both sides of the midline, thanks to being connected through the thoracolumbar and abdominal fibrotendinous spaces.
As these tendon centers are fundamental structures of the antigravity system, it follows that the movement generated by the cross chains will be influenced by the degree of tension of the antigravity system. This is further proof that tone precedes movement.
The trunk cross chains are continued with the flexors, extensors, and rotators of the upper and lower members. All these dynamic structures also have different degrees of flexibility or hypertonia, depending on the function they perform. Thus, hegemonies are described, which are categorized by the intensity and frequency of their use.
The muscles with antigravity function, the inspirers and the grippers, due to their almost constant demand for action, tend to hypertonia, as well as those that are little required, lose strength. The study of this functional map is the one that allows designing preventive and therapeutic body work, in relation to our myofascial system and our postural attitude.
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