The diaphragm is a thin, dome-shaped muscle that sits below the lungs and heart. It separates the chest cavity from the abdominal cavity and is the main muscle used for breathing.
Every time you inhale, your diaphragm contracts and moves downward. This increases space in the chest and helps pull air into the lungs. When you exhale, the diaphragm relaxes, moves upward and helps push air out. Most of this happens automatically, without you having to think about it.
What is the diaphragm?
The diaphragm is a large sheet of skeletal muscle located at the base of the chest. It forms a barrier between the thoracic cavity, which contains the lungs and heart, and the abdominal cavity, which contains organs such as the stomach, liver and intestines.
It is often described as dome-shaped because, when relaxed, it curves upward into the chest. During breathing, the diaphragm changes shape and position to help move air in and out of the lungs.
Although it works automatically most of the time, you can also influence it voluntarily when you take a deep breath, hold your breath, sing, speak, cough or practice breathing exercises.
Where is the diaphragm located?
The diaphragm is located below the lungs and heart and above the abdominal organs. It attaches to several structures, including the lower ribs, the breastbone and the spine.
In simple terms, it sits between your chest and belly. When it contracts, it moves downward toward the abdomen. When it relaxes, it moves upward toward the chest.
What does the diaphragm do?
The diaphragm has several important roles, but its main job is breathing. It helps create the pressure changes that allow air to move into and out of the lungs.
The diaphragm helps with:
- Inhalation, by contracting and moving downward.
- Exhalation, by relaxing and moving upward.
- Coughing, by helping generate pressure.
- Sneezing, by supporting forceful air movement.
- Speaking and singing, by helping control airflow.
- Vomiting and straining, by contributing to pressure changes in the abdomen.
The diaphragm also works with other breathing muscles, including the intercostal muscles between the ribs and, during labored breathing, some neck and chest muscles.
How the diaphragm works during breathing
Breathing depends on pressure changes. Air moves into the lungs when pressure inside the chest drops. Air moves out when that pressure rises again.
During inhalation
When you inhale, the diaphragm contracts and flattens. This movement increases the size of the chest cavity. As the chest expands, pressure inside the lungs decreases, and air flows in through the nose or mouth, down the airways and into the lungs.
During exhalation
When you exhale, the diaphragm relaxes and returns to its dome shape. The chest cavity becomes smaller, pressure increases and air moves out of the lungs.
Quiet breathing usually relies heavily on the diaphragm. During exercise, illness or shortness of breath, other muscles may help more actively.
Diaphragm anatomy: main parts
The diaphragm is not just a flat sheet. It has muscle fibers and a central tendon, and several important structures pass through it.
| Part or feature | Basic explanation |
|---|---|
| Dome shape | The relaxed diaphragm curves upward into the chest. |
| Central tendon | A strong central area where diaphragm muscle fibers attach. |
| Rib attachments | The diaphragm attaches to the lower ribs and helps expand the chest. |
| Sternum attachment | Part of the diaphragm attaches near the lower breastbone. |
| Spinal attachments | Muscle fibers attach toward the lumbar spine through crura. |
| Openings | Structures such as the esophagus and major blood vessels pass through openings in the diaphragm. |
What nerve controls the diaphragm?
The diaphragm is mainly controlled by the phrenic nerve. The phrenic nerves carry signals from the neck region of the spinal cord to the diaphragm, telling it when to contract.
If the phrenic nerve is damaged or not working properly, the diaphragm may become weak or paralyzed. This can make breathing harder, especially when lying flat or during exertion.
Why the diaphragm matters for breathing
The lungs do not have muscles that move air on their own. Instead, breathing depends on muscles around the chest and abdomen. The diaphragm is the most important muscle for inhalation because its downward movement expands the chest and helps air enter the lungs.
When the diaphragm is weak, paralyzed or restricted, a person may feel short of breath, breathe more shallowly or need to use accessory muscles in the neck and chest.
Common diaphragm problems
Several conditions can affect the diaphragm or how it works. Some are mild and temporary, while others may need medical evaluation.
Hiccups
Hiccups happen when the diaphragm contracts suddenly and involuntarily. The vocal cords close quickly afterward, creating the “hic” sound. Most hiccups are harmless and go away on their own, but persistent hiccups should be checked by a healthcare professional.
Diaphragm strain or irritation
The diaphragm can be irritated by certain digestive, chest or abdominal issues. Some people feel discomfort, tightness or pain that worsens with deep breathing, coughing or movement. Chest or upper abdominal pain should be evaluated if it is severe, new or concerning.
Diaphragm paralysis
Diaphragm paralysis happens when one or both sides of the diaphragm lose strength or movement. This can be caused by nerve injury, surgery, trauma, neurological disease or other conditions. Some people have few symptoms, while others develop shortness of breath, especially when lying down.
Diaphragmatic hernia
A diaphragmatic hernia occurs when abdominal organs move through an abnormal opening in the diaphragm into the chest cavity. Some cases are congenital, meaning present at birth, while others can occur after trauma.
Hiatal hernia
A hiatal hernia occurs when part of the stomach pushes up through the diaphragm through the opening where the esophagus passes. It is different from diaphragm paralysis and is often discussed in relation to reflux or digestive symptoms.
Symptoms that may involve the diaphragm
Diaphragm-related symptoms depend on the cause. Possible symptoms may include:
- Shortness of breath.
- Difficulty taking a deep breath.
- Breathing discomfort when lying flat.
- Chest or upper abdominal discomfort.
- Frequent or persistent hiccups.
- Weak cough.
- Fatigue during activity.
- Unusual breathing pattern.
These symptoms can have many causes, including heart, lung, digestive, muscle or nerve problems. A healthcare professional can help determine the cause.
When to seek medical help
Seek urgent medical care if breathing symptoms are sudden, severe or associated with warning signs such as:
- Chest pain or pressure.
- Severe shortness of breath.
- Bluish lips or face.
- Fainting or severe weakness.
- Confusion.
- Trauma to the chest or abdomen.
- High fever with breathing difficulty.
- Symptoms of stroke, such as face drooping, arm weakness or speech trouble.
If symptoms are severe or life-threatening, use local emergency services.
How diaphragm problems may be diagnosed
The evaluation depends on symptoms and medical history. A healthcare professional may consider tests that look at breathing, muscle function, nerve function or the structures of the chest and abdomen.
Possible tests may include:
- Chest X-ray, to look for diaphragm elevation or lung-related problems.
- Ultrasound, to observe diaphragm movement.
- Fluoroscopy, sometimes called a sniff test, to assess diaphragm motion.
- Pulmonary function tests, to measure breathing capacity and airflow.
- CT or MRI, if structural problems, trauma or tumors need to be evaluated.
- Nerve or muscle testing, if a nerve or neuromuscular cause is suspected.
Respiratory muscle function can also be assessed with tests such as maximal inspiratory and expiratory pressure measurements when muscle weakness is suspected.
Can you strengthen your diaphragm?
Some people use diaphragmatic breathing exercises to improve breathing awareness and efficiency. Diaphragmatic breathing encourages deeper breathing using the diaphragm rather than shallow upper-chest breathing.
These exercises may be recommended in some respiratory, stress-related or rehabilitation settings, but they are not a cure for all diaphragm problems. People with lung disease, recent surgery, severe shortness of breath or unexplained symptoms should ask a healthcare professional before starting exercises.
How to do basic diaphragmatic breathing
If a healthcare professional says it is appropriate, a simple diaphragmatic breathing exercise may involve:
- Sitting or lying in a comfortable position.
- Placing one hand on the chest and one hand on the abdomen.
- Breathing in slowly through the nose so the abdomen rises more than the chest.
- Relaxing the shoulders and neck.
- Breathing out slowly through the mouth.
- Repeating for a short period, without forcing the breath.
Stop if you feel dizzy, worse, short of breath or uncomfortable.
Quick summary
- The diaphragm is the main muscle used for breathing.
- It sits below the lungs and separates the chest from the abdomen.
- It contracts and moves downward during inhalation.
- It relaxes and moves upward during exhalation.
- The phrenic nerve helps control diaphragm movement.
- Problems can include hiccups, hernias, weakness or paralysis.
- Sudden or severe breathing problems need urgent medical care.
Frequently asked questions
What is the main function of the diaphragm?
The main function of the diaphragm is breathing. It contracts and moves downward during inhalation to help air enter the lungs, then relaxes and moves upward during exhalation to help air leave the lungs.
Where is the diaphragm located?
The diaphragm is located below the lungs and heart and above the abdominal organs. It separates the chest cavity from the abdominal cavity.
Can the diaphragm cause pain?
Diaphragm irritation, muscle strain, digestive problems, chest conditions or abdominal issues can cause discomfort that may be felt near the lower chest or upper abdomen. New, severe or unexplained pain should be evaluated by a healthcare professional.
What happens if the diaphragm is weak?
A weak diaphragm may make breathing harder, especially during activity or when lying flat. Some people may develop shallow breathing, fatigue, weak cough or shortness of breath. The cause should be evaluated by a healthcare professional.
What nerve controls the diaphragm?
The diaphragm is mainly controlled by the phrenic nerve, which carries signals from the spinal cord in the neck region to the diaphragm muscle.
Are hiccups caused by the diaphragm?
Yes. Hiccups involve sudden involuntary contractions of the diaphragm followed by quick closure of the vocal cords. Most hiccups are harmless, but persistent or severe hiccups should be checked.
Can breathing exercises help the diaphragm?
Diaphragmatic breathing exercises may help some people use the diaphragm more effectively and become more aware of their breathing pattern. They should not replace medical care for unexplained shortness of breath or suspected diaphragm disease.