Reference Muscle Latissimus Dorsi
About two thirds of the back is covered by the latissimus dorsi. This shoulder muscle can exert tremendous force on the shoulder joint (glenohumeral joint). It has two main attachment sites. The attachment site, labeled insertion, is on the upper front (anterior) of the humerus or upper arm bone. The attachment site, labeled origin, begins at T-7 (thoracic vertebra 7) and runs via its tendinous connections, all the way to the tailbone. It is a very large and powerful shoulder muscle.
There is a synergistic relationship between the "lats" in the back of the body and the "pecs" (pectoralis major ) in the front shoulder-chest area. In fact their attachment sites on the upper anterior humerus are very close together, practically on top of each other. Along with the teres major and posterior deltoid, they pull the raised arm downward during throwing, swimming, and hitting motions.
The lats and pecs also work together to adduct (to move toward the body midline) the arm or raise the body when the arm is fixed, as during climbing. Working together, the pecs and lats, prevent the downward displacement of the trunk when bearing weight on the arms, as in pushing up from a chair, walking with crutches, and in gymnastics, when performing on the rings or parallel bars.
We use our lats to do lifting and pushing, especially with overhead repetitive movements. When the latissimus dorsi is tight/contracted, the back arches to compensate creating compression in the spine. This is often the source of, or contributes to, low back pain.
Even though muscles never work alone, I find it helpful to use the term "reference muscle" as a guide for understanding specific movement patterns.
The following videos demonstrate some of the Hanna Somatic movements we use for releasing excess tension/contraction in the lats and their synergistic partners.
To release excess tension/contraction and lengthen muscle fibers, Hanna Somatic Educators start by mimicking the pattern of tightness. We make a voluntary contraction of the muscle group(s) involved in the pattern of tightness. This alerts the motor cortex which movement pattern and muscles we are focusing on. Then, using our motor cortex, we make a slow, controlled release out of contraction and toward muscle fiber lengthening. Remember, the motor cortex is the part of the brain that is responsible for voluntary movement. This process, called "pandiculation," was Thomas Hanna's unique contribution to the field of neuromuscular re-education.
All Hanna Somatic Movements are done slowly, comfortably, and as precisely as possible. We do not force and we not stretch. We work from within the muscles' neurophysiology to decrease excess muscle tonus (contraction) and reset and lower its resting tonus. The result is less or no pain, decreased joint stiffness, increased flexibility and strength, and a sense of easy and fluid movements as you go about your daily life.