DO - DEUTSCHE ZEITSCHRIFT FÜR OSTEOPATHIE (German Journal of Osteopathy) 1/2007
The Mediastinum and Intrathoracic Fascial Release
Eric Hebgen, Königswinter, IFAO
The mediastinum is the space enclosed by the two pleural cavities. This is one possible definition of the mediastinum, but it fails to reveal the importance of this compartment. No other space in the human body contains such a large number of vital circulatory structures in such a small area. There is no other region in the body where we can see the significance of fascial continuity and movement as clearly as in the mediastinum.
What I mean by this can be illustrated with one look at embryology. In an early developmental stage (day 24-28), after the yolk sac has been integrated into the embryo as the primary intestinal tube and a first cavity has developed, the mediastinum does not exist yet, but this is nevertheless an extremely important stage for its functional significance.
A bodily cavity exist, but it is not yet differentiated into an abdominal and a thoracic cavity - this only occurs later. What is of particular significance here is the lining of this cavity with mesodermal tissue. Later on, this is differentiated into the peritoneum, the pleura, and the pericardium/epicardium - in each case into a parietal and visceral lobe. This means that these three serous membranes share a common embryologic origin and are functionally related! Later, this functional connection is referred to in terms of the central tendon, by which we mean the fascial cord that extends from the base of the skull to the floor of the pelvis.
How are these two separate cavities formed? The key to this process is the migration of the heart from the cervical region into the thorax, which occurs as the result of the cranio-caudal collapse of the embryo in the fourth week of development. The heart originates in the cervical area and takes its fascial connections along when it migrates into the thorax. The connective tissue, or mesoderm, cranial to the heart also migrates into the thorax. There, it ends up caudal to the heart and forms the first still incomplete layer of separation between the newly formed cavities of the abdomen and thorax. The future diaphragm develops from this transverse septum, as well as the fascial tissue that we call pleuroperitoneal membrane, and the striated muscles in the wall of the torso. The division into the lung cavities and the mediastinum takes place in the thoracic cavity: The pericardium develops out of the lining of the thorax, the lobes of the lung grow from dorsal into the thorax. They also take the lining of the thorax with them as their exterior cover – hence the pleura is formed. The space that has now formed between the lungs, the diaphragm, the upper thoracic aperture, and the anterior and posterior endothoracic fascia (also the mesodermal lining of the primitive first cavity of the embryo) is called mediastinum.
The following key points are noteworthy:
- As the result of its migration from the cervical region into the thorax, the heart and pericardium have extensive fascial contact points in all three planes of the mediastinum.
- In an early stage of its development, the diaphragm is a fascia; even after its development is finalized, it retains the relevant properties.
- Pleura, pericardium, and peritoneum share a common origin and cooperate in functional terms as part of the central tendon. The mediastinum provides the space for this.
In conclusion, the mediastinum "functions" as fascia and part of the central tendon, and should also be treated as such, i.e. in fascial and intrathoracic terms. But before turning to that topic, let us take one look at the topography of the mediastinum. Here we find numerous important circulatory structures in considerable vicinity to each other and affected by a movement that is imperceptible at first glance. Now let us look at the "content" of the mediastinum from anterior to posterior: Behind the sternum, we find the heart sac, which is connected to the sternum via ligament. On top of the pericardium, roughly in the upper third of the sternum, is the thymus, which performs an important immunologic function during childhood. Lateral to the pericardium, we find the two phrenic nerves. Further toward posterior, so to speak as the next layer behind the pericardium and thymus, the upper third of the mediastinum contains the large vessels that emerge from the heart or run into it. Further again behind these, we find the trachea. At the level of TVB 4, this structure splits into the two main bronchial tubes, which are themselves in contact with the pericardium. In the upper third of the mediastinum, the esophagus is located, even further behind the tracheae and touching the pericardium only after the tracheal bifurcation. On the right side, the vagus nerve approximates the esophagus very quickly after entering the thorax; the left vagus nerve must first cross the arch of the aorta before it can also run together with the gullet toward caudal and across the diaphragm. Furthest toward dorsal, directly in front of the spinal column, we find additional circulatory structures: The azygos and hemiazygos veins, the thoracic duct, and in front of the heads of the ribs the sympathetic trunk. We can conclude a number of things from this list: The mediastinum is traversed by venous, arterial, lymphatic, sympathetic, and parasympathetic pathways with significance for the abdominal organs. The healthy functioning of these organs therefore depends on the structure “mediastinum.”
How does the mediastinum function? This space between sternum and spinal column, the two halves of the lung, the diaphragm, and the upper thoracic aperture is tightly packed with organs and conduits and in between, as if connecting them all, with fascial tissue. Consequently, all structures in the mediastinum are dependent on each other because they are attached to each other. Looked at from the outside, it appears as if there were very little movement in this space, but the situation looks very different from the intrathoracic perspective. Each day, we perform ca. 20,000 breaths. This creates constant pushing and pulling on the mediastinum in cranio-caudal and lateral direction. Hereby, the heads of the ribs move the sympathetic trunk in a particular fashion, which is certainly not for nothing! The heart beats ca. 100,000 times per day. This movement in turn causes continuous vibrations in the mediastinum. There is thus no other region in the body where we see as much movement or as many significant circulatory structures in one place as the mediastinum. All these structures apparently need this amount of continuous movement to carry out their tasks to the best of their ability. The articular, ligamentary, and muscular mobility of the thorax plays an important role in this context. If we find dysfunctions in these structures, we have at our disposal numerous treatments of the thorax and hence also of the mediastinum "from the outside,” but these are not the topic of the following discussion. Rather, I now want to introduce the fascial intrathoracic release of the mediastinum.
Intrathoracic Fascial Release
The difficulty in this method of treating the thorax lies in the fact that we are here, in contrast to other regions of the body, forced to evaluate the soft fascia through the hard osseous thorax. Hence we direct our attention and palpation deep into the thorax and there evaluate the fascial movements in layers, so to speak. Treatment follows from palpation in accordance with the general principles for treating fascia.
2.1 First Preliminary Exercise
The patient is in lateral position, the practitioner is standing behind the patient. Place one hand flat on the ventral thorax, the other at the same height and position on the dorsal thorax. With the ventral hand, apply pressure toward posterior until the posterior hand feels this pressure. Now repeat this exercise starting from the posterior hand. Lastly, move the hands and evaluate another area of the thorax in the same way. Hereby ask yourself the following questions: How do the different layers of the thorax feel under the pressure of palpation while you are passing through? Can you distinguish between the various layers? Do you have to vary the amount of pressure you apply to penetrate a layer?
2.2 Second Preliminary Exercise
Starting positions for patient and practitioner are as described above. Apply simultaneous pressure with the anterior and posterior hand until you sense the pressure of the other hand on its path through the thorax with each of your hands. Repeat this exercise in different locations along the thorax and try to move the layer where the two palpation pressures meet, now more toward anterior and now more toward posterior.
After you have familiarized yourself well with this preliminary exercise, you can now begin to evaluate the different fascial layers in the thorax. For this purpose, select an intrathoracic fascial layer as described above, maintain this pressure, and concentrate on the intrathoracic fascial movement: Is the movement dynamic and vital in regards to quality and quantity? Are there preferred movement directions? Now you are bound to ask yourself: What does "normal" mean after all? Is there a physiological movement? You should be able to affirm this. A physiological movement results from the embryologic migration that I have described above. Nevertheless, I think that we should not base our interpretation on the fascial movements that happened in the thorax at an early stage of life, without considering the actual compensation for dysfunctions. In my opinion, it is practically impossible to restore a physiological fascial movement in the thorax because it is intrinsic to fascial dynamics that they adapt to dysfunctions in the sense of spatial approximation to the disturbed structure. This adaptation occurs especially early in the mediastinum, due to its association with the central tendon. The question that we should ask ourselves should therefore be: What is the purpose of the fascial movement that we have actually perceived in the thorax? Is this a case of compensation and does it draw me towards the dysfunction or are there restrictions that are in need of treatment?
In a second step of this palpation, you now take action: Follow the perceived movement to find the area that this movement is running toward as a place of high fascial tension. Now move the fascia in all other directions of the space, to evaluate whether the movement is free - whether the fascial tension inside the thorax is normal. Hereby, you must not rely on a right-left comparison because, for example, the two halves of the lung are constructed differently and the heart is displaced somewhat to the left side. Over the course of time, you will gather enough experience to judge inter-individually what is "normal" and what is not.
By means of the palpation described above, you have discovered areas in the thorax that show high fascial tension in need of treatment. To treat these, again palpate into that layer of the thorax that you have evaluated as disturbed. Now you are able to treat, indirectly, directly, or by unwinding.
In the fascial layer to be treated, follow the fascial movements to their actual endpoint. There, you use manual pressure to hold the movement in the reached end position - even against a palpable countermovement by the fascia. After an individually determined length of time, allow the movement of the intrathoracic fascia to reverse direction and evaluate whether the dynamic has improved in terms of quality and quantity. If necessary, repeat the treatment.
In the layer requiring treatment, perform a countermovement to the fascia's own movement in the thorax by pulling manually exactly in the direction that you have discovered to be impaired in movement. Once you feel a strong pull of the fascia against your chosen direction, maintain this position until a release in the tissue occurs, which you will sense as sudden slackening in the fascial pull. If the movement is still not free after this maneuver, repeat the whole process.
In this method, you follow the fascial intrathoracic movement without influencing it until you reach a still point. You stay there with the tissue until another movement occurs. It is only now that you interfere correctively by directly facilitating the direction of the limited movement.
The diagnostic and therapeutic principles introduced here for one visceral cavity can be transferred to the abdomen as well. With a little practice, it is also possible to perform the examination and treatment with only one hand. You will also learn over time to evaluate the individual thoracic tissues (bronchial tubes, pericardium, hilum of the lung, etc).
The embryologic development of the mediastinum shows that this structure can be regarded as fascia. This space is so important for the viscera because essential pathways for the abdominal organs run through the mediastinum. As the result of the heartbeat and respiration, the mediastinum experiences a lot of movement. It is treatable with the technique of intrathoracic fascial release. Preliminary exercises prepare for this technique, which can be performed directly, indirectly, or as unwinding.
The mediastinum and intrathoracic fascial release The embryologic development of the mediastinum shows that this structure can be considered as fascia. This cavity is especially important for the viscera because major abdominal organ pathways travel through the mediastinum. Heartbeat and respiration cause the mediastinum to move continuously. The technique of intrathoracic fascial release can be used to treat the mediastinum. Preliminary excercises can prepare for this technique, which can be carried out directly, indirectly, or as unwinding.
Le médiastin et le « release » fascial endothoracique Le développement embryologique du médiastin montre que cette structure peut être considérée comme un fascia. Cet espace est très important pour les viscères car des voies de transfert principales pour les organes abdominaux passent par le médiastin. Dû à la pulsation du cœur et à la respiration, le médiastin est toujours en mouvement. On peut le traiter en appliquant la technique du « release » fascial endothoracique. Des exercices préliminaires préparent à cette manipulation directe, indirecte et comme « unwinding ».