What Does The Diaphragm Do?

The diaphragm is the primary muscle that drives breathing. It is a large, dome-shaped sheet of muscle that sits at the base of the chest cavity, separating the lungs and heart from the abdominal organs. When you inhale, the diaphragm contracts and flattens, creating more space for the lungs to expand and pull in air. When you exhale, it relaxes and returns to its dome shape, pushing air out.

Where Is the Diaphragm Located and What Does It Look Like?

The diaphragm sits horizontally across the body, roughly at the level of the lower ribs. Think of it as the floor of the chest cavity and the ceiling of the abdominal cavity. It is attached to the sternum (breastbone) at the front, the lower ribs along the sides, and the spine at the back.

At rest, it curves upward like an inverted bowl or a parachute. The right side sits slightly higher than the left because the liver presses up against it from below. This is normal anatomy, not a sign of a problem.

The muscle has three large openings that allow structures to pass between the chest and the abdomen. The esophagus passes through one opening to reach the stomach. The aorta — the body’s largest artery — passes through another. The inferior vena cava, which returns blood from the lower body to the heart, passes through the third. These openings are tightly sealed around the structures, so the muscle can move freely without creating gaps.

What Does The Diaphragm Do During Breathing?

Breathing is the diaphragm’s main job, and it performs it with every breath you take. When the diaphragm contracts, it moves downward and flattens. This increases the vertical space in the chest cavity. The pressure inside the chest drops below the pressure of the outside air, and air rushes into the lungs. This is called inhalation, and it is an active process — the diaphragm does work.

Exhalation is mostly passive. The diaphragm relaxes, moving upward into its dome shape. The chest cavity shrinks, pressure rises, and air flows out. You do not normally need to push air out; the natural elasticity of the lungs and chest wall does the work.

The diaphragm is responsible for about 75 percent of the air you move in a normal resting breath. The remaining 25 percent comes from the accessory muscles in the neck and between the ribs, which assist when you need to breathe more deeply or more rapidly, such as during exercise.

One common misconception is that the lungs expand and pull air in on their own. They do not. The lungs have no muscles. They are passive elastic organs that follow the movement of the diaphragm and chest wall. If the diaphragm stops working, the lungs cannot inflate on their own.

What Other Jobs Does the Diaphragm Have?

Breathing is not the diaphragm’s only function. It also plays a role in several other important bodily processes.

Pressure management in the abdomen. When the diaphragm contracts along with the abdominal wall muscles, it increases pressure inside the abdominal cavity. This pressure helps with functions like urination, defecation, and childbirth. It also helps stabilize the spine when you lift something heavy — this is why weightlifters are taught to brace their core before a heavy lift.

Vomiting. The diaphragm contracts forcefully during vomiting. This increases abdominal pressure and helps expel stomach contents. It also coordinates with the muscles of the throat to prevent vomit from entering the lungs.

Swallowing and acid reflux protection. The diaphragm has a muscular ring around the esophagus where it passes through. This ring acts as a second sphincter, helping to keep stomach acid from flowing backward into the esophagus. When this mechanism weakens, acid reflux and heartburn can develop. This is why hiatal hernias — where part of the stomach pushes up through the diaphragm — are closely linked to reflux symptoms.

Lymphatic circulation. The movement of the diaphragm acts like a pump for the lymphatic system. Lymph fluid, which carries immune cells and removes waste from tissues, has no central pump like the heart. It relies on muscle movement to circulate. The rhythmic motion of the diaphragm during breathing helps move lymph through the chest and back into the bloodstream.

What Happens When the Diaphragm Malfunctions?

When the diaphragm does not work properly, the effects are felt quickly because breathing is affected. The severity depends on the cause and whether the problem affects one side or both sides.

Diaphragmatic paralysis occurs when the nerve that supplies the diaphragm — the phrenic nerve — is damaged. This can happen from neck or chest surgery, trauma, certain neurological diseases, or sometimes without a clear cause. If one side of the diaphragm is paralyzed, it cannot contract. The paralyzed side moves upward when you inhale instead of downward, which reduces the amount of air you can take in. Many people with one-sided paralysis have no symptoms at rest but experience shortness of breath with exertion. If both sides are paralyzed, breathing becomes severely impaired, and most people require mechanical ventilation support.

Diaphragmatic hernia is a condition where an organ — usually the stomach or part of the intestine — pushes through a defect or weakness in the diaphragm. This can be present at birth (congenital) or develop later in life (acquired). A hiatal hernia is the most common type, where the upper part of the stomach slides through the esophageal opening. Large hernias can compress the lungs and cause shortness of breath. In severe cases, the blood supply to the herniated organ can be cut off, which is a surgical emergency.

Diaphragmatic spasms cause a sudden, involuntary contraction of the muscle. The most familiar type is a hiccup. Hiccups are brief, repeated spasms of the diaphragm that cause a sudden intake of air that is cut off by the closing of the vocal cords. Most hiccups resolve on their own within minutes. Persistent hiccups lasting more than 48 hours can be a sign of an underlying medical issue, such as nerve irritation, electrolyte imbalance, or certain medications, and should be evaluated by a doctor.

Diaphragmatic flutter is a much rarer condition where the diaphragm contracts rapidly and repeatedly. It can cause shortness of breath, chest discomfort, and visible movement of the abdominal wall. It is poorly understood, and treatment options are limited.

How Can You Keep Your Diaphragm Healthy?

The diaphragm is a skeletal muscle, and like other skeletal muscles, it responds to training. Regular aerobic exercise strengthens the diaphragm and improves its endurance. This is why people who exercise regularly feel less breathless during physical activity — their breathing muscles have adapted to work more efficiently.

Breathing exercises specifically target the diaphragm. Diaphragmatic breathing, sometimes called belly breathing, involves consciously engaging the diaphragm to take slow, deep breaths. To do it, place one hand on your chest and one on your abdomen. Breathe in slowly through your nose so that your abdomen rises more than your chest. Breathe out slowly through pursed lips. This technique is commonly taught to people with chronic obstructive pulmonary disease (COPD) because it can reduce the work of breathing and improve gas exchange.

Some research suggests that inspiratory muscle training — using a device that provides resistance when you inhale — can strengthen the diaphragm and other breathing muscles. This approach is used in some rehabilitation programs for people with respiratory conditions and in some athletic training protocols. The evidence for benefit in healthy people is mixed, and no standardized recommendation exists for general use.

Smoking damages the lungs, but it also impairs the function of the breathing muscles. Smoking causes chronic inflammation and increases the work of breathing, which places extra demand on the diaphragm over time. Quitting smoking is one of the most effective ways to protect both lung and diaphragm function.

When Should You See a Doctor About Diaphragm Problems?

Diaphragm problems can be difficult to diagnose because their symptoms overlap with many other conditions. Shortness of breath, for example, is a symptom of heart disease, lung disease, anemia, and many other conditions, not just diaphragm dysfunction.

Seek medical evaluation if you experience any of the following:

• Shortness of breath that is new, worsening, or occurs with minimal exertion
• Chest pain or pressure that is not clearly related to activity
• Hiccups that last longer than 48 hours
• Difficulty swallowing or food getting stuck
• Severe heartburn that does not respond to over-the-counter treatments
• A visible bulge or asymmetry in the abdomen or lower chest

Diagnosing diaphragm dysfunction typically involves imaging studies. A chest X-ray can show an elevated diaphragm on one side, which may suggest paralysis. Fluoroscopy — a real-time X-ray — can show whether the diaphragm moves normally during a sniff test. Ultrasound is also used to assess diaphragm thickness and movement. Pulmonary function tests measure how well air moves in and out of the lungs, which helps determine how much the diaphragm dysfunction is affecting breathing.

Treatment depends entirely on the cause. One-sided paralysis that causes no symptoms may require no treatment at all. Symptomatic paralysis might be treated with surgery to placate or fold the paralyzed diaphragm, which can improve breathing capacity. Hernias typically require surgical repair. There is no medication that directly strengthens the diaphragm.