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I guess many of us have heard of the serratus anterior muscles – they run from the edge of the shoulder blade forwards to the side of the ribs, and are used to pull the shoulder blade forwards. They are sometimes called the “punching muscles” for obvious reasons, and also contribute to shoulder stability and strength, being heavily used for instance by aerialists. In well muscularly developed people, they are visible as a set of muscle ridges on the side of the ribcage. However the name serratus anterior suggests there might be a serratus posterior too. In fact there are two of them, superior and inferior. I got an introduction to them in a recent ST class with Sue Kelso where she got us to massage our upper back against the wall using a small hard rubber ball, first moving the shoulder blade to the side and out of the way. The area was surprisingly tender in me, suggesting that I hold chronic tension in the muscles there. Later I looked at the anatomy, and found that the area of tenderness most closely corresponded to the superior serratus posterior (upper bands of muscles in the picture). They run from the vertebral processes to the ribs (definitely not onto the shoulder blade). The muscles are in a layer just under the rhomboids. The action of the muscles is described as elevating and pulling back the ribs. I suspect that I was holding tension there as a way of helping to stand upright and counter my tendency to forward stoop. A stretch for these muscles would be something like the ST “3 Amigos” which uses a forward bend in the upper back, and drawing the shoulders down and forward to increase the movement of the ribs. Then that got me thinking about the inferior serratus posterior muscles (the lower band of muscles in the diagram), which I think solves a puzzle that I’ve had for ages. These muscles run from the lower vertebral processes upwards to the lower ribs. Their action is described as depressing the lower ribs. However, if the front of the ribs are fixed (e.g. by strong muscular activity around front of the ribcage) the action will become lifting the lower vertebrae. In the days when I used to bend over gently backwards and put my hands on the floor behind me, and then slowly stand up again, I found it enormously helpful if about 2/3 of the way up, I was able to contract a band of muscles around the lower back near the bottom of the ribcage. It was as though someone had put a hand on my back in that area, and was lifting me up. Until now, I’ve never been able to work out what these muscles might be. But now I suspect that they were the inferior serratus posterior muscles (I certainly felt them in the correct area), in the second mode of action described above, lifting the lower vertebrae on a fixed ribcage (remember once you are in a backbend, the direction of the action will be different). Stretches for this area include deep spinal rotations combined with a forward bend (many exercises). I also find that now when doing my (now minimal) standing backbends, I tense up both the upper and lower of groups of muscles in preparation. I wonder, does anyone else do this stuff and does anyone have any corresponding experiences? Thanks, Jim.