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The Diaphragm and Thoracic Sling

Working with my Nerve Release students and I wanted to share some information that's not frequently discussed in terms of healthy function in the horse but really should be on the forefront -

The diaphragm.

It is one of the first and most profound structures in the body that is negatively affected by an underdeveloped thoracic sling.

Common Symptoms of dysfunction in the diaphragm are:

Holding of Breath Sympathetic State/Hypervigilance Dip in front of withers Back tension / pain Atrophy in medial glutes Overdevelopment of Hamstrings Lack of hind end engagement Girth Cramps / Black out/Falling when girthed.

(These symptoms can also be other pathologies, always seek Veterinarian consult first). The anterior (front) part of the diaphragm attaches to the sternum. The sternum is a long, flat bone located in the center of the thorax connecting the rib bones via cartilage. This attachment helps secure the diaphragm's position within the body and plays a role in maintaining its dome shape.

It also shares a strong fascial attachment to the pericardium, which then attaches to the visceral fascia of the esophagus and trachea all the way up onto the hyoid.

The posterior part of the diaphragm has dorsal attachments at T17/18 to L4 where it shares a fascial attachment to the psoas.

(We sit directly over the top of the Diaphragm) and it is suspended from ribs 9 to 17/18.

By attaching to the sternum, lumbar vertebrae, and the lower ribs, the diaphragm forms a complete partition between the thoracic cavity (housing the heart and lungs) and the abdominal cavity (containing the digestive and reproductive organs).

This arrangement allows the diaphragm to effectively carry out its primary function, which is to facilitate the process of respiration.

As the primary muscle responsible for breathing, the diaphragm plays a crucial role in the respiratory system as well as the parasympathetic system.

During inhalation, the diaphragm contracts and flattens, increasing the volume of the thoracic cavity and decreasing air pressure within the lungs. This causes air to rush in and fill the lungs.

During exhalation, the diaphragm relaxes and returns to its dome shape, decreasing the volume of the thoracic cavity and increasing air pressure within the lungs, which pushes the air out.

In addition to its respiratory function, the diaphragm also aids in stabilizing the core and maintaining intra-abdominal pressure.

**Which is essential for proper posture, balance, and movement**.

The primary nerve responsible for the function of the diaphragm is the phrenic nerve, which originates from the cervical spinal cord, specifically the spinal roots C3, C4, and C5.

The phrenic nerve provides motor innervation to the diaphragm, controlling its contraction and relaxation during the breathing process.

(Another major reason why horses being ridden with brace in their ventral neck is so damaging as it conpresses this nerve).

The Vagus nerve also passes through and innervates into this area and is arguably what causes the black out/ girthing problems.

Additionally, the diaphragm receives minor sensory innervation from the lower intercostal nerves (T5-T11) and the subcostal nerve (T12).

These nerves provide feedback on the diaphragm's position and tension, enabling the body to regulate and adjust diaphragmatic movements for efficient respiration. . To paint a full picture then -

When the horse is collapsed through its thoracic sling and therefore has a negative-angle in the spine, the heart and sternum are pushed down and forward.

This not only puts pressure on the heart, but it pulls the diaphragm along with it, putting strain on the lumbar attachments, causing the back to tighten.

While the attachments of the diaphragm are being pulled down and foreword, the shared fascial attachment into the psoas is being pulled in the opposite direction due the horse having to use it's psoas to stabilize it's spine and anchor it's balance point from also being pulled down.

This causes significant strain over the lumbo sacral plexus and into the hamstrings, causing symptoms such as sciatica, stringhalt and shivers due to the resulting nerve compression.

Because a healthy and correctly placed diaphragm supports the structures of the abdominal cavity containing the digestive and reproductive organs, displacement of it can also cause restriction of the organs and fascial adhesions to form.

In summary -

It has the capacity to complete change the structure of the horse for the better or the worse. How can you help you horse with these issues?

Nerve release work can't be beat - Here is a list of my certified bodyworkers to find one in your area-

Pillar 1 Walking in straight lines, 5-10 minutes a day does wonders for it as well, here's a free video all about that -

If you want someone to personally walk you through some manual work to help, you can find our trainers here to set up a distance session-

Pictures below are before and after a single session of diaphragm release work with focus on the thoracic sling by Betsy Vonda and Kaylie Hanson


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