What are the anatomical features of the latissimus dorsi?
The latissmus dorsi is the large, flat muscle that covers most of our mid and lower back. It works hard for us in many ways and our Tai Chi practice is a great way to keep it healthy, vital and strong.
One of its unique features is that it attaches (originates) from 5 different areas (see diagram). From the top, it attaches to the inferior border of the scapula. It then fixes to the spinous process (outer tip of the vertebra) of the 7th thoracic vertebra and all along the spine, ending at the spinous process of the 5th lumbar vertebra. It does this via the wide thoraco-lumbar aponeurosis or fascia (white area in image) that forms part of its muscle structure. At the lower end, this fascia attaches to the top of the pelvis at the iliac crest, including part of the sacrum.
As we move towards the outside, the latissimus dorsi tethers itself to the lower 3rd and 4th ribs before it finally inserts itself into the bicipital grove (8 cm long tract) at the top of the humerus of our arm.
What are the main functions of our latissmus dorsi?
In terms of movement, the lastissmus dorsi works to extend (move down and backward) adduct (bring towards the midline) and internally rotate (turn inward) the arms. Many of our standing Jongs that focus on various arm movements are made possible by these actions of the latissimus dorsi. Can you visualize them? The scapula is also stabilized by the scapular portion of the muscle, allowing us to keep our arms light as we raise them overhead. Without this important stabilization, we would be unable to raise our arms fully, severely limiting our reaching ability in any movements we carry out in our daily lives.
The latissimus dorsi further serves as an accessory muscle in deep inspiration and forced expiration. This is possible as a result of its attachments to the lower ribs. When our arms are fixed, contraction of the latissimus dorsi elevates the ribs to expand the rib cage, helping us to take a deep breath. When we cough and sneeze, the contraction of its fibers also helps compress the thorax so we can force the air out as we do so. Such a wonderfully impressive muscle!
Which Tai Chi postures engage the latissmus dorsi the most?
Of great interest to our Tai Chi practice is the myofascial connection of the latissimus dorsi to the pelvis and sacrum. Its function in this area is to provide the entire pelvis with greater stability, especially during weight bearing (preparing us for the dan-yu drop). And because of the exceptional geography of the muscle, our arms (where the tendon inserts) are connected to the upper pelvis thanks to this myofascial connection.
When we drop the arms, for instance, the tendon of the latissimus dorsi becomes engaged, allowing us to achieve a more stable drop of the pelvis (as in coming back in the tor-yu, arms down and in). It is important to understand that the latissimus dorsi does not create the drop itself. That action is left to other muscles such as the psoas. Rather, it helps position the pelvis into stable alignment so that the subsequent drop performed is balanced and effective.
Several movements in Tai Chi activate and rely on a sound and flexible latissimus dorsi. Brush knees involve alternating arm swings that extend our arms behind us, followed by a returning forward while our arms rotate ( turn) inwards towards the midline. Single whip involves extension of the arms while opening the body to the same side, engaging the portion of the muscle fibers attached to the ribs. Our standing Jong in which we cross hands at the midline (adduction) in preparation to raise our arms overhead while internally rotating them (palms facing upwards) is performed mainly by the latissimus dorsi.
What are the health benefits we gain from this latissimus dorsi interplay?
As we can now appreciate, the latissimus dorsi is a vast muscle in both length and breadth and requires tremendous flexibility and strength to function well. Its muscle mass provides us with balance, co-ordination and stability in almost every movement we make starting with our arms down to our trunk and pelvis. With its critical connection between our upper and lower limbs, this incredible muscle enables us to perform moves that require complex dynamics. Without it, we would be severely restricted in our ability to function independently.
Due to its stabilizing effect, our overall posture is maintained and improved, minimizing any uncomfortable back pain we may be experiencing. Shoulder range of motion is enhanced and protected. Its secondary function in respiration cannot be underestimated as well. We have all sensed how our breathing can become laboured when ill with the flu, and our latissimus dorsi has been quietly part of this healing if unwanted congestion develops.
The slow, gentle and continuous movements of our Tai Chi practice are what provide the latissimus dorsi with the essential elasticity and strength needed to work for us. The compound directions within each posture we adopt and the interplay between the four extremities and the spine are what keep it vital and alive. And, in the end, we are the ones who reap the tremendous health benefits it provides!
Thank you to Master Moy for teaching us this foundationally healing art!
Copyright ©️ 2024 Lila Zitouni
Translation by Jordi Awarita, Cathy Filion
For myself these explanations help relaxation. Brief visualization helps the mind/body connection during moving & sitting meditation. Thank you for this.
Lila, Wonderful article. Has been a great help in my understanding of the mechanics of this muscle, its possible connection to the issues I am having with my lower back, and how I can adapt my Tai Chi practice to deal with those issues.