The Diaphragm: Beyond Breath (Part 1)
- May 30
- 3 min read
By Gavin Buehler
If you have been following along with our articles, we have been reviewing the importance and function of the core. The deep core which is responsible for providing stability for your spine and pelvis along with protecting vital organs, consists of four parts that include the diaphragm, multifidus muscles, pelvic floor and transversus abdominis. These muscles create your “core cannister,” which we discussed in a previous article. While zooming in on specific areas of the body can often lead to tunnel vision where we lose sight of how everything works together as a whole, it is still important to break things down to understand each individual part so that we can have a better understanding as to how it might contribute and integrate with the whole.
In this article we’re going to begin a closer look at the diaphragm.
This structure is well known as the key muscle for breathing, however we never really look past that when mentioning it. But it has multiple functions, and its fascial reach spans from head through to toe making it one of the most impactful structures of the entire body. To make things even more interesting, it is one of few, but for most of us the only structure that we have both voluntary and involuntary control over enabling a link to our autonomic systems that we generally cannot consciously control.
The Anatomy
Before we can understand more about diaphragmatic functions, we need to have an anatomical picture. A full anatomy overview of the diaphragmatic areas and attachments is well beyond this article. However, I will go through its typically mentioned areas and attachments and a few interesting points. This will still seem pretty detailed. (For keeners this medical journal reference will provide an in-depth look.) Let’s dig in.
The diaphragm is a thin dome shaped sheet of skeletal muscle approximately 2-4mm thick that separates the thoracic (ribcage area containing lungs and heart) and abdominal cavities. Its attachments are typically grouped into sternal, costal, and lumbar origins, all converging into a central tendon.
1. Sternal Attachment
The smallest portion of the diaphragm.
Arises from the posterior (back) surface of the xiphoid process of the sternum.
Usually consists of two small muscular slips.
Landmark structure:
Xiphoid Process
2. Costal Attachments
The largest portion.
Originates from the internal surfaces of ribs 7–12 and their costal cartilages.
The muscle fibers interlock with the fibers of the abdominal wall muscles, especially the transversus abdominis.
Key attachment points:
Inner surfaces of ribs 7–12
Costal cartilages of ribs 7–12
3. Lumbar Attachments
The strongest and most complex attachments.
These arise from the lumbar vertebrae via the right and left crura and the arcuate ligaments.
Right Crus
Attaches to the anterior (front) surfaces and intervertebral discs of L1–L3 (sometimes L4).
Longer and larger than the left crus.
Left Crus
Attaches to L1–L2 (sometimes L3).
Arcuate Ligaments
Median Arcuate Ligament
Connects the right and left crura.
Forms the anterior (front) boundary of the aortic hiatus (the opening in the diaphragm where the aortic artery travels through.)
Medial Arcuate Ligament
Extends from the body of L2 to the transverse process of L1.
Arches over the psoas major muscle.
Lateral Arcuate Ligament
Extends from the transverse process of L1 to the 12th rib.
Arches over the quadratus lumborum muscle.
4. Central Tendon (Insertion)
All muscular fibers converge here.
Thin but very strong aponeurotic center.
Fused superiorly with the fibrous pericardium surrounding the heart.
Quick Summary Table
Region | Main Attachments |
Sternal | Posterior xiphoid process |
Costal | Internal surfaces of ribs 7–12 and costal cartilages |
Lumbar | Right crus (L1–L3), Left crus (L1–L2), arcuate ligaments |
Insertion | Central tendon |
Clinical Relevance
The lumbar attachments are particularly important because they influence:
Respiratory mechanics
Lumbar spine stability
Fascial continuity with the psoas major and quadratus lumborum
The passage of structures through the diaphragm (esophagus, aorta, inferior vena cava)
It is a crucial point of information transferance
This is where the diaphragm becomes much more interesting than the commonly known "breathing muscle." Anatomically, it's positioned at the center of a large fascial and pressure-management system that links the rib cage, spine, pelvis, and abdominal cavity from an immediate standpoint, but extends further through the head all the way down to the big toe! It is a “breathing network” additionally influencing posture, vascular, nervous and lymphatic systems, gastroesophageal functions while serving as an important exchange point of information and a source of information itself.
In the next installment of this series we'll look at how the diaphragm functions as a breathing mechanism and take a closer look the fascial net that encompasses it.
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As always, these articles and videos are for entertainment and educational purposes only. Please consult a health professional before attempting new exercises or protocols, as the following suggestions may or may not be appropriate for you.
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