As mentioned in my last newsletter the “diaphragm” is the major muscle during the act of breathing as well as playing a deep, foundational role in maintaining your posture and “core” stability. But to most, the diaphragm is too deep and mysterious to be a significant part of your musculoskeletal system. Yet, it is probably one of the most important muscles of your body that is vital to your overall health and wellbeing.
In looking at its design and structure, the diaphragm can be compared to a parachute when based on its origin, insertion, and shape. It originates on the lower border of the ribs wrapping all the way around the body. Unlike any other muscle in your body, it literally folds over onto itself to create its insertion point which is located at the center of the body referred to as its “central tendon.”
The “central tendon” is actually an aponeurosis which forms the top of the dome-shaped diaphragm. It blends with the fibrous pericardium above which is the membrane enclosing the heart to keep it in place. The diaphragm is like a hemisphere that arches up into the thoracic cavity forming both the roof of the abdominal cavity and the floor of the thoracic cavity.
The human torso or trunk is divided into the thoracic and abdominal cavities. The thoracic cavity includes everything contained in your rib cage which extends from the base of the neck to a few inches above the navel. Essentially, it is like a sealed off container for the lungs, with the heart resting in between. The abdominal cavity, on the other hand, consists of the part of your trunk that begins at the lower border of your rib cage and fills the space down into the pelvis containing your digestive organs. The diaphragm is the physical separation between these two cavities.
During inhalation, your thoracic cavity must be enlarged to allow air to rush into your lungs. The thoracic cavity can be increased in size by expanding your rib cage upward and outward to increase the circumference of the cavity. This increase is due to the contraction of the muscles between the ribs called the “intercostal muscles.”
When taking a deep breath, muscles of your shoulders and muscles on top of your rib cage attaching to the neck and skull can also contract to lift your rib cage even higher. I know you have heard me mention the anterior, posterior, and middle scalene muscles that go from the neck to the rib cage during treatment. These muscles are considered “accessory” breathing muscles.
Each rib attaches to your spine in the back of your trunk so that as you inhale, each rib can move upward and out from your spine. This indicates that while your rib cage tends to move as a whole, segments of it can move in isolation. A natural pattern that is seen throughout the human body. The significance of this is that when your rib cage expands, you can see and feel movement around your entire trunk in back as well as in front.
The thoracic cavity is further increased by lowering its floor or by contracting the diaphragm so it no longer bulges up as far. When your diaphragm contracts, it flattens downward pressing on top of your abdominal cavity. This increases the pressure within your abdomen causing your stomach to “stick out.” That is, if your abdominal muscles are not too tight. Because of the diaphragm’s effect on your abdomen, emphasis of the diaphragm in breathing is often times referred to as “belly” or “abdominal” breathing.
During the exhalation phase of your breath, a decrease in size of your thoracic cavity occurs through the reversal of the process just described. The intercostals between the ribs, the muscles of the upper chest, and neck muscles attaching to the first and second ribs now elongate, allowing your rib cage to get narrow and drop mainly due to the downward pull of gravity on your ribs. Your diaphragm then rises back up into the thoracic cavity mainly due to the natural elasticity of your lungs to which your diaphragm clings.
The end result is a decrease in the circumference and depth of your thoracic cavity which then forces air out of your lungs as they are pressed flat. It is for this reason, breathing moderately deep with emphasis on the exhalation phase of your breath is an excellent and simple way of easing muscular tension of your neck, shoulders, and back.
In addition to its foundational role in your breathing, it plays a supportive role in your posture. Many postural and movement specialists today have shown that the diaphragm plays a vital role in postural stabilization that is under your volitional control and that the diaphragm can perform its respiratory function and postural tasks simultaneously.
It wasn’t too long ago that the diaphragm was never mentioned in the discussions of core and core-stability training. And even today, there are still many posture and movement experts who give advice about core stabilization, but neglect to mention the diaphragm. It is only mentioned as an afterthought and not emphasized as it should be.
However, the diaphragm does much more than affect your breathing and core stability. One of the most interesting facts about the diaphragm is that it has an indirect effect on your parasympathetic nervous system (PNS) which is part of your central nervous system (CNS).
The PNS is also part of your autonomic nervous system (ANS), so it is not under your conscious control, but is controlled involuntarily through internal reflex activity of the CNS. But, your PNS can be indirectly influenced by your diaphragm and breathing.
When looking closer at the structure of the diaphragm, you will see that the vagus nerve, the 10th cranial nerve, runs directly through the esophageal hiatus of the diaphragm. Remember in my newsletter about the vagus nerve, it impacts your gut as well as your digestion, heart rate, and your body’s immune response.
The vagus nerve which is the longest of the cranial nerves is the main nerve circuitry of the PNS. It sends signals up and down its length telling your brain when you are hungry or full, signals your stomach to start the digestive process or peristalsis, slows down your heart rate, and will even activate your immune system’s inflammatory stress response.
During the act of breathing, the natural movement of the diaphragm around the vagus nerve can stimulate your parasympathetic response and tone. In this case, the more your diaphragm moves and massages the vagus nerve, the more the PNS is facilitated. To increase your PNS tone, you merely need to practice your “diaphragmatic or belly” breathing. But that is easier said than done! Due to poor posture, stress, general tension, and just too much sitting during this pandemic, most of you have poor diaphragm movement.
The diaphragm can also affect the tone of the PNS through the natural cadence of the breath and its connection to your heart rate. That is because when you inhale, your heart rate naturally increases. This naturally occurs to speed up filling of the low-pressure environment of your lungs. As you exhale, the heart rate naturally slows down to avoid excessive pressure in the arteries of your lungs. This variable heart rate with breathing is referred to as “respiratory sinus arrhythmia” (RSA).
The ANS will automatically modulate your heart rate through pressure receptors or baroreceptors in your arteries. As your heart rate increases with inhalation, your body creates a sympathetic response, the polar opposite of the PNS. As your heart rate decreases with exhalation, your body creates a parasympathetic response.
In this way described, your diaphragm is a mediator of your ANS and can be a powerful regulator of your parasympathetic and sympathetic tone. By emphasizing the different phases of your breath, you have an innate ability to affect your PNS and SNS tone. In emphasizing your exhalation phase, you can increase PNS tone and help encourage the “rest and digest” response of your CNS. Conversely with your inhalation phase emphasized, you can increase the SNS tone that encourages the “fight or flight” response of your CNS.
Besides this strong and indirect connection between the diaphragm and your CNS, there are also several distinct roles the diaphragm can play at an energetic level that is pretty much an unknown in Western medicine yet recognized in Eastern philosophy and medicine.
In the Eastern traditions, you are as well as all humans and creation itself are recognized as energy. In fact, energy is all there is. Understanding that you are an energetic being first and foremost is an important step for many of you to take in your never ending journey toward optimal health and fitness.
Energy is what is seen as the building block of all matter. The same energy that makes up your flesh as a human being is the same energy that composes the bricks of a house and for that matter the tree in the yard. It’s all the same energy which is constantly flowing and transforming.
In fact, it is now believed by many scientists that the secret of the universe we live in is in the terms of energy, frequency, and vibration. This is a very simplistic explanation for a very complex matter. “No pun intended!” But now at the “quantum” level it all looks like one large pool of energy soup, a vast ocean of energy which is always flowing with different concentrations and essences at various points.
Therefore, life is seen as an energetic process from sub-atomic particles, amino acids, peptides, on up to your DNA and the cells that eventually form to make you which resonates with your own, unique, signature frequency of energy.
The “Einstein” equation was simply the recipe for the amount of energy required to create the appearance of mass. It means there are not two fundamental entities or polarities described as something material and the other immaterial, but only one entity and that is energy.
For thousands of years ancient religions and cultures around the world have described various forms of life, creation as energy. The East Indians and Tibetans may have called it “prana” and the Japanese “Ki”, but they are talking about the same thing. The Chinese call it Qi or Chi which is described as origin of life energy. Qi/Chi is not an element of any kind, but rather it is the origin of everything. Since Qi/Chi is the ultimate energy from which the universe and the essence of all existence is derived, Qi/Chi is immune to the limitations of time and space.
Traditional acupuncture, a branch of traditional Chinese medicine, which is a tried and tested healthcare system practiced over thousands of years in China and the Far East gives us a complex and detailed understanding of the body’s energetic balance.
It is the diaphragm that has the capacity to regulate the flow of Qi/Chi throughout your body. In Chinese medicine, the diaphragm is actually seen as the gateway between the upper and lower parts of the human body. It plays a role in regulating the ascending and descending functions of the human body. It holds the potential to transport Qi/Chi, blood and fluids to the entire body that provides the nourishment for the brain and human organs in addition to managing respiration and digestion.
On top of that, the diaphragm also has a connection to all 14 meridians of Chinese acupuncture because all these pathways which Qi/Chi flows through the body pass through it either superficially or internally. Each of these meridians also connect internally to the organs giving the diaphragm the unique and tremendous potential to affect your heath and wellbeing.
Superficial meridians supply energy, Qi/Chi to the muscles and tissues while the internal meridians control the deeper functioning of the internal organs. Again, this also occurs via the parasympathetic nervous system and the diaphragm as already mentioned.
These regulatory functions of Qi/Chi provided by the diaphragm allow it to act as the moderator of yin and yang energy in your body, a very important treatment principle of Chinese medicine. In order for one to be healthy, there needs to be a balance between yin and yang.
Yin/Yang energy can refer to a wide range of things within Chinese philosophy and medicine, but yang can refer to the Qi/Chi energy produced within the human body. Yin, on the other hand, refers to the blood, body fluid, or simply referring to substance which includes muscle and body mass. The equivalent of Yin/Yang energy in our Western thought and medicine would be our autonomic nervous system and its parasympathetic and sympathetic divisions. Just as with our ANS, the yin and yang energy restrain and balance each other while an imbalance may give rise to illness depending on which organ or energy meridian is affected.
So what does the diaphragm have to do with yin/yang energy? Well the diaphragm has the potential to be fierce and intense in its role to nourish your body in very “yang” way. For instance, the diaphragm quickly steps into action when needed like when you sprint requiring a quicker exchange rate of O2. However during most of your day, you don’t need to pay any attention to your breath. Your breath instead just quietly meanders through its role in a quiet and seamless way. Thus, more “yin” qualities of your body. It is this yin quality that calms your body just like your body’s parasympathetic nervous system.
Therefore, the diaphragm has the power to command nourishment to the entire body and at the same time has the capacity to be effortless and soft in its transactions that embody both the “yin” and “yang” qualities and sometimes simultaneously.
On a more emotional level, the diaphragm is also found to be the bridge between the conscious and unconscious emotions in Chinese Medicine. It is the diaphragm that tends to be the place where you store unconscious emotional tension or grief. During times of high stress or emotional intensity in your life, your diaphragm can get rigid and bound down creating more problems due to a decrease in the oxygenation of tissues throughout your body.
Tension in the diaphragm can then affect the PNS tone contributing to the stress response cycle or affect the meridians that pass through it. This impact on the meridians has the power to affect the entire energetic, Qi/Chi system.
So as you can see, the “diaphragm” is a very important muscle of the human body. With its ability to regulate the upward and downward movement in the body and its connection to the meridians of Chinese medicine, it has the capacity to affect both the regulation of energy (Qi/Chi) throughout your body as well as functioning of your body’s internal organs. In combination with its close connection to the parasympathetic nervous system and its regulation of yin and yang energy as well as your emotions, you can see how powerful this one deep and mysterious muscle can be. But more importantly, how it is vital to your health and wellbeing. Hopefully now, you can see why breathing is considered our primary and most important movement pattern. Be well.
Important facts about the diaphragm you probably did not know:
•Together with the heart, the diaphragm forms our rhythmic center.
•It connects to both autonomic and the somatic (body) nervous system.
•The diaphragm is the only muscle crossing the body’s midline.
•It is attached to the spine and involved with our core stability.
•Contraction of the diaphragm pumps the lymph up the thoracic duct.
Terry