Diaphragm: anatomy, function, and abnormalities


The diaphragm, often called the thoracic diaphragm, is the large muscle that separates the chest from the abdomen. This muscle plays an important role in breathing because its alternating movements help you breathe in and out.


It is not easy to recognize that you have a health problem that affects your diaphragm. Symptoms, if present, can include problems like heartburn , nausea, and shortness of breath. Diaphragm-related diseases can range from minor problems like hiccups to more serious problems like hiatal hernia or paralysis. Diaphragm problems can usually be treated with medicine or surgery.


The diaphragm is a parachute-shaped fibrous muscle that runs between the chest and abdomen, separating the two large cavities. It is asymmetrical, since the right dome is larger than the left. The diaphragm has holes that allow certain structures to occlude the chest and abdomen.

With rhythmic movement, the diaphragm remains attached to the ribs, sternum (breastbone), and spine.


The diaphragm is primarily made up of muscle and fibrous tissue. The central tendon is the largest portion of the diaphragm that attaches the diaphragm to the ribs.

The diaphragm has three large holes (orifices):

In addition to these holes, several smaller holes also allow the passage of smaller nerves and blood vessels.


The diaphragm covers the body from front to back. This is the floor of the chest cavity and the roof of the abdominal cavity .

Your heart, lungs, and the upper part of the esophagus (food tube) are in the chest cavity above the diaphragm. The lower part of the esophagus, stomach, intestines, liver and kidneys is located below the diaphragm in the abdominal cavity.

The left and right phrenic nerves send signals to control the diaphragm, which receives its blood supply primarily from the lower phrenic arteries.

Anatomical variations

In a healthy person, the anatomy of the diaphragm may differ slightly. For example, the left or right side may be slightly higher or lower without affecting physical function.

During pregnancy, a woman's enlarged uterus can slightly displace the abdominal space, raising the diaphragm and causing shortness of breath.


The diaphragm plays an important role in respiration (respiration). Most of the time, the diaphragm moves involuntarily.

Your thoracic diaphragm also plays a role in helping muscles move during labor, bowel movements, urination, and heavy lifting. This muscle also helps maintain the flow of lymphatic fluid throughout the body .

Diaphragmatic movement

When the diaphragm is activated by a nerve, it contracts and flattens. This reduces pressure and increases space in the chest cavity, allowing the lungs to expand as you inhale. When the diaphragm relaxes, the chest cavity becomes smaller and the lungs release air .

Your diaphragm contracts rhythmically and involuntarily (for example, during sleep) due to signals from your brain. You can also voluntarily contract your diaphragm to hold your breath, breathe deeper or faster, or to tense your muscles .

Diaphragmatic breathing is a technique used to strengthen the diaphragm, allowing more air to flow in and out of the lungs without fatigue of the pectoral muscles. This is also called abdominal breathing and is often used by singers .

Related conditions

There are several diseases that affect the thoracic diaphragm. Traumatic injuries or anatomical defects can affect muscle function and movement of the diaphragm can also be impaired due to conditions such as nerve disease or cancer.


When the diaphragm becomes irritated, for example from fast eating or drinking, it can involuntarily contract many times and cause hiccups. Hiccups occur when air is exhaled at the same time as the diaphragm contracts .

Hiccups usually go away on their own, but there are treatments for persistent cases.

Hernia of the esophageal opening of the diaphragm.

A hiatal hernia is a bulge from the lower esophagus (and sometimes the stomach) into the chest cavity. This defect can cause heartburn, indigestion, and nausea.

Several conditions can cause a hiatal hernia , including increased pressure in the abdomen (due to obesity or pregnancy) or straining (such as lifting heavy objects, coughing, or having a bowel movement). Smoking increases the risk, as do some genetic diseases such as Ehlers-Danlos syndrome .

Sometimes hiatal hernias can only be treated with medications and lifestyle measures. In some cases, surgery is recommended to reduce the risk of complications such as volvulus (twisting) and strangulation (cutting off the blood supply) of the tissues.

The surgery can be done openly or laparoscopically. With the latter method, several small incisions are made in the abdominal cavity and the reconstruction is performed with special instruments equipped with a camera .

Diaphragm hernia

Diaphragmatic hernias are structural defects that allow abdominal organs to enter the chest cavity. They can be present from birth or, less frequently, can result from trauma.

  • Congenital : The diaphragm does not develop properly in about 1 in 2000 births. As a result, part of the contents of the abdominal cavity can enter the chest cavity. This can lead to incomplete lung development (pulmonary hypoplasia ). Significant progress has been made in supporting children with congenital diaphragmatic hernia. For example, an artificial diaphragm can be made surgically .
  • Acquired: Diaphragmatic hernias can also occur in adults as a result of trauma, such as road traffic injuries, gunshot wounds, or stab wounds. These hernias can cause life-threatening problems, such as compression of the lungs, and generally must be repaired with surgery.


Conditions that affect the nerves that control the diaphragm can lead to muscle weakness or complete paralysis .

These nerves can be damaged due to several mechanisms :

Diaphragm weakness caused by nerve injury can cause shortness of breath, especially when lying down. Treatment may require treatment, surgery, rehabilitation, or mechanically assisted breathing support.

Chronic Obstructive Pulmonary Disease (COPD)

Lung disease, especially COPD , can cause diaphragm weakness. This happens through a progressive process that involves a number of factors.

COPD leads to hyperinflation of the lungs , which physically press on the diaphragm. The entire muscle becomes flat and its mobility is reduced. Over time, cells in the diaphragm change due to excessive stress, causing them to lose their ability to function at their maximum strength. Chronic oxygen deprivation due to COPD also damages these cells .

Diaphragm weakness caused by COPD causes increased shortness of breath.


Tumors can spread to the diaphragm or take up space in the chest or abdomen, putting physical pressure on the diaphragm and affecting its ability to function. For example, mesothelioma , cancer of the pleura (the lining of the lungs), can spread to the diaphragm. Lung cancer , lymphoma , and stomach cancer are other types of cancer that can affect the diaphragm.

Symptoms can be gradual or abrupt and can include shortness of breath, pain when breathing, or loss of consciousness. Treatment generally includes surgical removal of the tumor, radiation therapy, and / or chemotherapy.


An evaluation of the diaphragm can include many tests that are tailored to the medical problem in question. Imaging tests, such as chest or abdominal computed tomography (CT) , magnetic resonance imaging (MRI) , or ultrasound, can reveal anatomical changes or tumors.

Diagnosis of a hiatal hernia may include tests such as upper gastrointestinal endoscopy or barium ingestion , which evaluate the structure of the gastrointestinal system. And the diaphragm problems associated with COPD can be evaluated using respiratory tests such as spirometry or pulmonary function tests .

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