Two seemingly opposite things are true about depth in bodywork: First, there is nothing you’re ever touching but skin. All else is literally untouchable (unless you decide to become a surgeon). Once you’ve accepted that limitation, however, another truth emerges: There is no structure in the body that you cannot contact with therapeutic intent. Every bone, every foramen, every ligament, every joint capsule, every fold between organs — all are accessible with the right combination of angle and approach.
The problem is that when learning bodywork, you try too hard, and you confuse depth with pressure. But they are different qualities, and in some places — such as the ribcage or the cranium — too much pressure will make surface tissues opaque and prevent your contact with anything deeper. But if you cultivate a practice of “just enough” pressure, and then pair it with reasonably accurate anatomy, you can profoundly affect deep structures in the body.
So it is with the phrenic nerves — innervators of the diaphragm — as they spill over the anterior scalene and begin their journey down each side of the heart. Once inside the ribcage, they descend the crevice between pleura and pericardium, and must contend daily with the pressures and tensions conferred by the movements of the mediastinum. The pericardium, especially, is often quite joined to the phrenic nerves. Which makes sense, since the pericardium then connects seamlessly into the diaphragm’s central tendon. Near the bottom of the heart, each phrenic nerve sends a branch anteriorly, toward either side the xiphoid process. Then, upon joining the diaphragm, each nerve branches in multiple directions to innervate the whole dome of the diaphragm. These branching points are of particular interest since adverse neural tension can converge there.
OK, let me ask the obvious question here: Is it really possible to put your hand on the outside of someone’s ribcage and make a specific therapeutic contact with the phrenic nerve? In my experience — and in the experience of many students — yes, absolutely. After some practice, most practitioners wouldn’t even call it difficult. Furthermore you can learn to feel quite a lot of detail inside the ribcage, and make keen palpatory assessments as to what’s sliding, what’s under tension, and what’s limiting the motion of the whole breathing apparatus.
It helps to begin with simple abstractions, and then zoom in when you get curious. To begin with, it may be useful to visualize the heart and diaphragm as one structure, with a heart-balloon above and then a muscular skirt below. This shape is the ‘phrenic neurofascia’ — a single fabric with the phrenic nerves along its major axes.
Try this: Place a few fingertips from each hand on your sternum. Acquaint yourself with the landscape — the divots between rib attachments, the horizontal ridges and fascial lines, the broad manubrium above, the xiphoid extending below. This is your depth: the sternal surface. Feel the slippery bone when you make tiny circles, and feel the firm grab of fascia when you carry the skin in one direction. Now make a depth adjustment. Instead of sliding on the sternum, take the sternum with you. You’ll be tempted to push hard — but stick with medium pressure. Just slide upward until the fascia engages. And then pay close attention: the sternum has joined your motion. If you gently go farther, you’ll notice a slight pull into your rectus abdominis. If you add a sideways component to your hook, you’ll feel the ribs compress slightly on that side. If you breath deeply, you’ll gain a sense of the sternum as the center of the rib cage, and you might feel how the ribs connect to the spine.
Now adjust your depth again, and imagine the underside of the sternum. Realize that the sternum is firmly attached to a tight fascial balloon — the pericardium — that surrounds the heart and stretches toward the spine. The sternum is no longer an object of your curiosity; it has become your tool for contacting the next layer. Try to keep your pressure the same, and explore the curved expanse of the pericardium. You can hook into its front surface, a mere half-centimeter from your fingertips, or your intention can reach into the top, the sides, the back. Can you feel the valley between the heart and lungs? Can you hook into the broad attachment to the diaphragmatic dome? Take another deep breath, and feel the pericardium become taut as the diaphragm descends.
I call the phrenic nerves the “neurofascial axis” of pericardium-diaphragm. The nerves are part of the pericardium’s fabric (indeed, they innervate the pericardium), and you can create space, mobility and tensile balance in the phrenic nerves by doing the same with the whole landscape. Once you become used to engaging the interior in this way, you’ll often be able to find local adhesions, contractures, and bands of tension, whose resolution coincide with profound changes in breathing.
When in doubt, look at pictures, and then try again. As your mental picture improves, the shape of the pericardium will emerge naturally in your palpatory vision. You will realize that the apparent hardness of the sternum is no obstacle at all if you know how it’s connected. The question of pressure is easy: what level of pressure feels comfortable for your patient? What level of pressure allows you to feel the most detail in your object of inquiry?