Chapter 1: The Structure and Function of Breathing

This is a chapter 1 summary of “Multidisciplinary Approaches to Breathing Pattern Disorders” by Leon Chaitow. The second edition will be coming out this December, and you can preorder it by clicking on the link or the photo below



Breathing has been something I have been interested in very much since I first learned about its power from Bill Hartman and through the Postural Restoration Institute, and this excellent book is a great way to get a full overview.

The first chapter covers too much anatomy to go through every little detail in my short blog post. So study up.  Here are the highlights.

Structure, Function, and You

In order to have favorable respiration, structure makes all the difference. Adequate thoracic, ribcage, and breathing muscle mobility must be restored and maintained in order to uptake a quality breath. This can be achieved via re-education and training.

Realize too that psychological distress can also play a huge role in how we breathe. Disorders such as anxiety and depression can have corresponding breathing dysfunctions.  It may be the way the body responds to ensure survival.

Ergo, when attempting to change breathing patterns favorably, one must address both structural and psychological factors.


Homeostasis is the body’s process to normalize itself. If too many homeostatic-disrupting tasks are occurring at one time however—such as nutritional deficiencies and toxin ingestion—homeostatic function can become overwhelmed.  This systematic stress can lead to breakdown and a switch to heterostasis, in which the body must be treated. We can restore homeostasis via the following:

  • Take away as many undesirable adaptive factors as possible.
  • Enhance, improve, and modulate defensive and repair processes.
  • Treat symptoms without further burdening the system.

A general rule of thumb when addressing these areas: The weaker a patient is, the lighter the intervention must be.

Normal Breathing

There are several benefits to having optimal respiratory function:

  • Allows gas exchange.
  • Enhanced cellular function so the brain, organs, and body tissues perform normally.
  • Permits normal speech.
  • Involved in non-verbal expression.
  • Assists in fluid movement.
  • Mobilizes the spine.
  • Enhances digestive function

Air takes a fascinating journey when it enters our body. It goes through the following passageway

Nose –> Nasopharynx –> oropharynx –> laryngeal pharynx –> larynx –> trachea –> bronchi –> bronchioles

The two breathing strategies we utilize are nose and mouth breathing. Nose breathing is slow and rhythmic; utilized for sleep, rest, and quiet activity. But when we need large air volumes, mouth breathing comes into play. Mouth breathing requires much less resistance compared to the nose, and involves intercostal and anterior neck muscle activity.

Regardless of which strategy is used to breathe, the following occurs at the diaphragmatic level:

  • Diaphragm descends during inhalation; pulling the central tendon down.
  • Abdominal viscera resist the diaphragm from descending.
  • This resistance fixes the central tendon, causing the ribs to displace laterally.
  • At the same time, the sternum moves superiorly and anteriorly.
  • The combination of the above two leads to thoracic cavity expansion.
  • Greater breath volumes lead to accessory muscle utilization.
  • Abdominal muscle tone allows for correct viscera position so an appropriate amount of central tendon resistance can occur.

At the gas exchange level, air travels via the following pathway:

Nasal cavity and mouth –>  trachea –> bronchi –> bronchiole –> alveoli

Luke, I am your Fascia

Lung function can also be affected by fascial links throughout the body.  There is a direct fascial connection from the base of the skull to the diaphragmatic apex. Thus, stress in one area along this pathway can affect areas along the same location. As an example, changes in cervical spine or diaphragm position can lead to changes in breathing patterns.

You can also see fascial connections between the diaphragm, cervical spine, and pleura.  You can often see that the pleura can be affected with impairments in the prior regions.  For example, there have been dissections in which degenerated lower cervical structures also have corresponding fibrotic change to the pleuropulmonary attachments.

Ain’t no Bones About it

From a spinal perspective, breathing has a large effect on joint mobility; namely in the frontal plane. Every time we inhale, the odd segments (C3, T7) become more mobile, with the even segments increasing mobility during exhalation. This effect decreases as we travel down to the lower thoracic segments. The exception for this mobility is the cervicocranial junction, in which all three planes become more mobile upon inhalation. Taking this phenomenon into account, it may be helpful to utilize breathing cycles during mobilizations depending on which segments you wish facilitate.

Neural Regulation and Breathing

The brain works on controlling respiration in order to maintain balanced concentrations of oxygen and carbon dioxide. Respiratory control centers are located in the brainstem via three primary nuclei groups:

  1. Dorsal respiratory group – Found in the medulla. This area creates inspiratory movements and is responsible for the basic breathing rhythm.
  2. Pneumotaxic center – Found in the superior part of the pons. This area controls the filling phase of breathing.
  3. Ventral respiratory group – Found in the medulla. This area causes both inspiration and expiration. However, this area is inactive during quiet breathing.

While not a brain area, the Hering-Breuer reflex is an important neurological phenomenon. Located in the nerves of the bronchi and bronchioles, this reflex prevents lung overinflation via sending messages to the dorsal respiratory center via the vagus nerve.

Most of the above is in reference to quiet breathing. We can use a cortical overriding system via spinal neurons to respiratory muscles to consciously change breathing patterns.

This strategy is utilized in day-to-day activities such as speaking and singing. There is also some evidence that the cortex and thalamus drive some normal respiratory function. These areas are likely what we target and are likely originators for breathing pattern disorders (BPDs) and hyperventilation syndromes (HVSs).

Autonomic Fun

You cannot talk breathing without mentioning the autonomic nervous system (ANS).  There are two divisions of the ANS; the sympathetic (SNS) and parasympathetic (PNS) nervous systems.  The SNS deals with flight, fight, or freeze responses; and its neurons connect to the head, neck, heart, larynx, trachea, bronchi, and lungs. So we can see a vast number of areas that are affected if the SNS is dominant.

The PNS, on the other hand, deals with visceral functions aka rest and digest.  These areas govern the lungs, cranial, and pelvic regions.

There is also a third nervous system called the non-adrenergic noncholinergic (NANC) system, which contains inhibitory and stimulating fibers. The main neurotransmitter for this region is nitric oxide.

When inhibitory neurons in the NANC are active, smooth muscle relaxation and bronchodilation occur via calcium ions, with the opposite occurring via NANC’s stimulatory C fibers.

The Muscles of Respiration

The two thoracic-based muscle groups that influence respiration can be broken down into extrinsic and intrinsic. Extrinsic muscles position the torso; which influences shoulder, arm, neck, and head placement. As we learned previously, the position of these areas can influence breathing mechanics.

The intrinsic muscles predominately focus on moving thoracic vertebrae or the rib cage, and are the money muscles associated with respiration.

To get more specific, there are several muscles that work on inspiration. The king of course is the diaphragm, which provides 70-80% of the inhalation force. Other muscles that assist inspiration include lateral external intercostals, parasternal internal intercostals, scalenes, and levator costarum.

When we need an extra inspiratory kick for more demanding activities, we will often use accessory muscles to facilitate this process. These muscles include sternocleidomastoid (SCM), upper trapezius, pectoralis major and minor, serratus anterior, latissimus dorsi, serrratus posterior superior, iliocostalis thoracis, subclavius, and omohyoid.

We also have muscles that can perform exhalation, but understand that exhaling is primarily a passive process. We exhale based on elastic recoil from the lungs, diaphragm, pleura, and costal cartilages.

But sometimes you may want to utilize muscles to force an exhale. The guys for this would include interosseous internal intercostals, abdominal muscles, transversus thoracics, subcostales, iliocostalis lumborum, quadratus lumborum, serratus posterior inferior, and latissimus dorsi.