The Diaphragm – Functional Anatomy and Clinical Application as it relates to Lumbar Stability
The lumbar spine is a complex structure, requiring stability in movement, while resisting forces in a variety of planes. Several mechanisms assist the lumbar spine in maintaining stability. Adequate mobility in both the hips and thoracic spine set up the lumbar spine to succeed in maintaining stable segments.
One very important structure that helps integrate lumbar stability is the diaphragm. While many practitioners focus on the ability of the diaphragm to maintain an adequate breath, they forget it plays an integral part in providing stability and mobility to the lumbar vertebrae.
The diaphragm is attached to lumbar spine via the crura tendon. Although thin, this central tendon is a very powerful force producing structure. The right crus tendon attaches to the anterior surface and intervertebral fibrocartilage of spinal levels L1-L3. The left crus tendon has attachments at spinal levels L1-L2. Since there are two separate tendinous insertions the left and right sides of the diaphragm can act independently of each other.
Through the work of Myers, Stecco and others we have discovered the diaphragm has many connections that influence function of the lumbar spine. The crura tendons connect fascially to the anterior longitudinal ligament. This area, according to Myers, is the meeting point of the upper and lower portions of the deep front line where, “walking meets breathing”. Here the diaphragm also shares connections with the quadratus lumborum, psoas major, and kidneys. With such a complex series of attachments the diaphragm not only affects the musculoskeletal system, but can also influence the adrenal glands and digestion. On the right side of body the falciform ligament forms a connection between the diaphragm and the liver. This dense structure is often mistaken as an abnormal adhesion during treatment.
Lastly, the diaphragm is innervated by nerve roots c3-c5 in the cervical spine. It is imperative that the clinician rules out the cervical spine, as well as phrenic neuropathy prior to integrating lumbar stability and breathing pattern re-education. The presence of such lesions may lead to mixed results while trying to achieve optimal lumbar stability.
Although clinical emphasis often centers on lumbar spine stability it still requires movement. Through adequate balance of static and dynamic restraints the lumbar spine is able to flex, extend and rotate in a precise and intricate manor. The primary balancing act occurs between upward tension exerted by the diaphragm, and downward force exerted by the psoas major. An optimal balance of this mechanism contributes to efficient co-contraction of the small segmental stabilizers and large abdominal musculature. This helps provide a strong stable abdominal cavity. Failure to achieve this results in inadequate motion of individual lumbar vertebrae, and compensatory movement patterns.
Dysfunction in the diaphragm and lumbar spine may present for a number of reasons. The inability to breathe properly, will certainly affect function. Breathing is taken for granted, as it is automatically driven by our nervous system. A clinician should be mindful that the nervous system, like any system, can get lazy, injured and adapt. If a patient needs more oxygen, the body has to supply the demand. A change in respiratory rate or increase in the use of secondary respiratory muscles will alter the length of the thoracic cavity. This will increase oxygen delivery to tissue, but not without sacrificing thoracic cavity mobility. Without correct rib expansion and movement of the thoracic spine the diaphragm eventually loses strength, and the body begins to adapt.
Stability – Mobility – Dysfunction
The joint by joint theory used in the functional movement screen [FMS] and selective functional movement assessment [SFMA] states that certain joints require mobility while others are designed to be stable. Stability does not mean that segments remain fixed and stable, unless such a demand is placed on the body. More often the body is required to have controlled stability as a joint rolls, tilts, or glides.
In cases of low back pain patients can easily alter stability and mobility of the diaphragm. With optimal function tendinous and fascial structures at attachment sites remain healthy. This allows for interlayer sliding and normal joint motion. Adequate joint mechanics drive proprioceptive input to the brain and creates optimal function. With prolonged postures tissue and joint health changes. Tissue under sustained low grade mechanical load becomes of poor quality and can develop fibrosis. Fibrotic tissue does not move well and creates increased tension in muscles and fascia.
The following actions can occur while attempting to achieve balance between all sides of the spine. When the amplitude of a diaphragmatic contraction decreases, the aponeurosis of the crura tendon can increase in tension. This not only drives dysfunction in the diaphragm, but restricts motion of the L1-L3 segments. In response to upper segmental fixation the lower lumbar spine, segments L4-L5, can become hypermobile.
In an attempt to normalize itself, the body will recruit a number of restraints that if not balanced, create faulty stability. As the psoas major opposes the diaphragm it creates both a compressive force and anterior shear on the lumbar segments. To equalize, the spine activates posterior spinal restraints. The multifidi help to counteract the psoas major and control anterior shear forces.
If this mechanism becomes dysfunctional the nervous system attempts to increase lower lumbar stability through recruiting static restraints, the ilio-lumbar ligaments. When short the ilio-lumbar ligaments prevent anterior glide of L4-L5 and restrict motion of sacroiliac joints. The end result can be a lumbar spine that is partially or fully fixated and dynamically very unstable.
A patient may present to you in any stage of this balancing act. In most cases the patient is no longer able to safely flex or extend the lumbar spine. As the spine needs to bend, compensatory patterns occur at the thoraco-lumbar junction. In time permanent positional change of the diaphragm can occur relative to the lumbar vertebrae. Soon after symptoms arise, these can vary from general soreness and fatigue to discopathies or derangements at L4-L5-S1. Sprains to the ilio-lumbar ligaments are also common, and may indicate more advanced staged dysfunction as there is distinct loss of dynamic lumbar stabilization in these cases.
Next week I will follow up with a simple blog (with videos) on clinical application and rehabilitation, in treating patients with similar clinical presentations. As always questions and comments are appreciated. Pass it around if you enjoy it!Email This Post