Notes on Anatomy and Physiology: Slings at the Front, Slings at the Back

For awhile now, we’ve been delineating hand to foot continuities that run throughout the body, providing strength, flexibility and a more developed sense of one’s body in space as they unfold. These patterns of uninterrupted flow, created by sequences of muscle, tendon, fascia and bone, come and go with movement.

We saw, last time, how motion of the hands helps create lines of pull that travel by various routes up into the torso. Our task today is to look for some of the strings that will convey these impulses from the torso down into the pelvis, legs and feet.

Back of the torso

A good place to start is at the back of the trunk. Remember that you can enlarge an image simply by clicking on it.

The next two drawings provide an overview of what Myers calls the Back Functional Line. Both illustrations reveal the same continuous line of pull running across the back and linking up each hand with the opposite leg.


Fig 1 The Back Functional Line. Myers, page 170

Fig 2 Diane Lee refers to this same line as the posterior oblique sling. No matter the name, the linkages connect thorax, pelvis and leg. Lee, page 52

Setting off from the left side, we begin with the left latissimus dorsi at its origin on the left upper arm, follow down to where the tendons of the latissimus merge with the thoracolumbar fascia, cross the midline over to the right gluteus maximus on the other side, travel with the right vastus lateralis as it passes along the outside aspect of the thigh, and end up where the vastus lateralis inserts onto the right tibia just below the knee cap.

If we had started with the right latissimus, we would have ended up at the left tibia. These two potential lines of pull crisscross the back of the torso to form an X. I use the word “potential’ because we can choose to either engage these lines or leave them dormant.

Other links carry the line eventually to the foot but you get the idea: myofascia working together with bone to form a continuous chain.

Now, let’s examine elements of these back lines in a little more detail, starting with the latissimus dorsi and thoracolumbar fascia.

Fig 3 A posterior view of the torso, showing the latissimus dorsi-thoracolumbar fascia-gluteus maximus connection. On the right, the latissimus dorsi and other superficial muscles have been cut away to reveal some of the deeper muscles. Biel, page 194

Notice that the fibers of the latissimus dorsi and thoracolumbar fascia on one side follow the same trajectory as the contralateral gluteus maximus.

Fig 4 A view of the posterior aspect of the right gluteus maximus. The line of pull from the left latissimus dorsi travels across the midline to the right gluteus maximus by means of the thoracolumbar fascia. Biel, page 309

The gluteus maximus takes off from the sacrum, coccyx and posterior iliac crest (hip bone), runs diagonally down and across the buttock and attaches to the upper femur and the fibrous iliotibial tract.

Fig 5 A side view of the right thigh with the large vastus lateralis partially covered by a fibrous band known as the iliotibial tract. Biel, page 295

The vastus lateralis is one of the four muscles making up the quadriceps femoris, the largest muscle in the body. It starts its journey at the upper femur right where the gluteus maximus comes to an end and proceeds to run down the lateral thigh, terminating at the upper shin bone just below the knee cap.

Front of the Torso

The following image depicts the elements making up a line that connects the hand, shoulder and rib cage with the contralateral pelvis and leg – this time along the front surface of the body. Myers named this chain the Front Functional Line.

Fig 6 A line of pull that runs from one hand across the front surface of the trunk to the other side of the pelvis and leg. Myers, page 170

This time, on the left side, the sequence begins with the origin of the left pectoralis major at the upper left arm, runs with the pectoralis onto the chest, continues down the abdomen with the rectus abdominis to the pubis, and then crosses over to the right leg by means of the adductor longus. Of course, the right arm connects to the left leg in the same manner. Once more, two lines intersect as they cross the torso to connect one arm with the contralateral leg.

The anterior oblique sling is shown below. Described by Diane Lee and Andrew Vleeming, it is clearly similar to the central portion of the Front Functional Line.

Fig 7 The anterior oblique sling connects the external oblique muscle of the anterior abdominal wall with the midline fascia, the contralateral internal oblique abdominal muscle (not shown) and the adductors of the thigh. Lee, page 52

Opposite lines often work in reciprocity, one lengthening while the other shortens. The anterior oblique slings are doing this in the photo below.

Fig 8 In this man, the anterior oblique sling running from the right ribs to the left pelvis is contracting while the opposite sling running from left to right agrees to let go and lengthen. It is the task of the central nervous system to arrange for these two slings to work in tandem and with the proper timing. Myers, page 135

As we look briefly now at the links in this chain, recall that the pectoralis major runs from the front of the humerus to the medial half of the clavicle, the sternum and the cartilage of the first 6 ribs.

Fig 9 A front view of the right pectoralis major as it hooks the arm into the collar bone, sternum and rib cage. Notice the direction of the muscle fiber. Neumann, page 162

Starting from the chest wall at the cartilage of ribs 5,6 and 6, the rectus abdominis picks up from where the pectoralis major left off and travels down the front wall of the abdomen to the pubis.

Fig 10 A view of the anterior abdomen, showing the rectus abdominis connecting the rib cage with the pubis. Neumann, page 389

At the pubis, the adductor longus takes over from the rectus muscle, crosses the midline and attaches to the inside edge of the femur that is opposite to the hand where the line commenced. As before, each hand connects to the contralateral leg.

Fig 11 The adductor longus links the pubis to the thigh. Biel, page 314

Thus, front and back, there are big tendons or myofascial lines that provide added strength and precision to the movements of the limbs by connecting them across the body to their opposite. Left upper with right lower and left lower with right upper. In this way, the trunk adds its power to that of the limbs.

The final drawings show these lines in action as someone prepares to throw the javelin. Imagine how these lines are similarly activated as we open up in Brush Knees. There are differences, of course, partly because the javelin thrower is leaning back as he prepares to release the javelin. In Brush Knees, the torso remains more upright and the front hand has the same amount of  intention as the back.

Fig 12 The lines in action. The top drawing depicts the left back line as it shortens; the lower image displays the lengthening right front line. Imagine the upper person opening up to the left in Brush Knees while the person below opens up to the right in the same move. Myers, page 172

In the west, we have tended to study a muscle, joint or region of the body in isolation. This does provide rich details about how a part functions on its own. But it does not reveal how the parts work with one another to ensure that the organism as a whole functions well. Whatever muscle, tendon and bone may do on their own, they are also bundled into precise sequences that establish specific lines of force and structure.

We can see that moving confidently through the world is aided by:

  • good bones, joints and ligaments
  • supple, strong chains of myofascia – linkages of muscle, tendon, fascia and bone
  • neural programming capable of activating in proper sequence those myofascial lines of force and
  • a mindful, calm spirit.

To respond when things fall apart, we need to know how they are meant to work together. The concept of one big tendon helps us grasp how the hands, head and feet are linked. How the body maintains global stability while moving, and retains flexibility while creating strength.

In the last few articles, we have examined a few of the body wide continuities that form, dissolve and then reappear as we make our way through the world. There are others. Just remember they exist. Look for them as you move and use your practice of the Taoist Tai Chi™ internal arts of health to help keep them soft and robust.

1. Anatomy Trains, Second Edition, 2009, Thomas W. Myers, Churchill Livingstone Elsevier, ISBN 978-0-443-10283-7

2. The Pelvic Girdle, Third Edition, 2004, Diane Lee, Churchill Livingstone, ISBN 0 433 07373 2

3. Trail Guide to the Body, Third Edition, 2005, Andrew Biel, Books of Discovery, ISBN 0-9658534-5-4

4. Kinesiology of the Musculoskeletal System, Second Edition, 2010, Donald A. Neumann, ISBN 978-0-323-03989-5

Bruce McFarlane MD

© Taoist Tai Chi Society of Canada 2010


Filed under Anatomy and Physiology, Health Watch

10 responses to “Notes on Anatomy and Physiology: Slings at the Front, Slings at the Back

  1. Lynda McLay

    wonderful concept. It will hopefully help me understand my own danyu, which over 10years I still find difficult to experience balance in applying the machanics of this very important part of our Tai Chi. Thank you sincerely for your time and sharing with us who are interested. Have a great Christmas.

  2. Ellen Rice

    Thanks for this. I have learned that the largest muscle is not the gluteus maximus as I have been teaching my grade five students from the teaching materials provided to me but is rather the quadriceps femoris. Although it is not the end of the world, I do feel better giving my students accurate information when teaching them required curriculum about what a body ‘system’ is and how it is necessary that the different body systems work together for optimal performance. I have developed a set of skeletal muscle stretches for gym class that help the children to remember a very few of the skeletal muscles that I require they know. (It is their science test to lead the class in gym by naming muscle groups used and demonstrating the stretches for each.) Knowing the names of muscle groups and how they feel in use helps the children to develop and integrate body knowledge into their everyday function just as you are helping us to do for Tai Chi. Developing mastery of the body in use is especially enjoyable when it is approached as play in Tai Chi. Thanks again.

  3. we surely learned lots from this article, and we learned each part of muscle and how they works. now i can start to particle each of my muscle, thanks

  4. Bruce,
    Thank you for including references to the biotensegrity model and my articles. You are very close to the biotensegrity model, but there are still several points with which I take issue. In the biotensegrity model, all muscles work all the time, muscles are never “dormant”. They work synergistically, never as antagonists. If we think of the bones as pulleys within a network of multiple ropes, all the ropes are in tension all the time and the movement is more a realignment of the pulleys (bones) within the continuous tension network. This would mean that every movement is a total body experience and never confined to a muscle, a joint, a limb. Fascia, (at every level), is totally integrated in the system, muscle and bone are merely condensations within the fascial network. The lumbo-dorsal fascia functions as part of everything else and it, (nor any other tissue), cannot be considered as having an isolated specific function, (i.e., “contract this muscle and it does that–“). I believe this is consistent with martial arts philosophy and a better match than the lever model or Anatomy Trains model.
    I would be happy to discuss details of how the biotensegrity model differs from the Anatomy Trains model, but that takes space and time and an open give and take.

  5. That was great.

    It seems to me that by focusing on the parts individually, we can digest them and then add them together to make a more integrated whole. And that means both looking at pictures of individual muscles and chains of muscles as well as doing exercises to feel individual muscles as well as chains of muscles.

    I’m starting to understand that with the “new” understanding of the body (tensegrity, myofascial meridians and all), we don’t have to throw out the old understanding (muscles as isolated units.) Rather both views help us to more fully understand the whole that is our body.

  6. Thank you for these great images. I’m studying fascia and these pictures were very helpful to me.

  7. I love this! Great pictures; they really tell the story about function. It’s important to treat the whole system and to train the while system, not just one body part, right?

  8. Kevin Teixeira

    Thank you for putting so many or the pieces together and explaining them so well. Can you take this a step further? I have read that fascia cells under go a change if stressed by a continuous load and can contract & release much like regular muscle cells. Your essays help explain then how Zan Zhuang (standing meditation ) helps lead to whole body strength, or One Big Tendon as you wrote elsewhere. The various body & arm positIons and mental exercises pull/separate/release this soft tissue fabric so that it strengthens. Would love to read an essay about the use of intentand Zan Zhuang on fascia.

  9. Katie Gerrish

    This topic was raised by my clinical educator whilst on clinical placement, I was told to research Myofascial slings, and was apprehensive that I wouldn’t understand or be able to apply this to my anatomy – your page has made it very clear and straightforward to me – thankyou it has been very helpful.

  10. Thanks, Bruce.
    Your articles have re-enforced understanding of principles of movement uncovering otherwise hidden essential structures of balance.

    There is an issue that my 64.5 years has brought to bear on my practice of tai chi over the past 27 years: destruction by inflammation of joint covering tissue. Osteoarthritis has greatly reduced my mobility in the knees and changes my gait. Gentle and frequent donyus and toryus are necessary as opposed to hundreds at a time.

    Sooner or later, knee replacements are looming unless some other tai chi practice can restore destroyed joint lining.

    Thank you again, Bruce, for your inspiration over the years. You checked out my knee joints one night about 5 years ago at CIT week at Orangeville.

    Any development of your understanding of the body’s ability to regenerate the above-described joint tissues? My knee specialist here in Tampa holds the opinion that my knees are beyond regeneration.

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