Diaphragm (Human Thorax) Location, Anatomy, Function and Position (2023)

The Human Diaphragm

The word ‘diaphragm’ is used to describe several structures in the human body and in particular the thoracic, urogenital and pelvic diaphragms. The most important and largest of these structures is the thoracic diaphragm. It is a flat sheet of muscle that is responsible for breathing. The diaphragm essentially pulls and pushes against the lung causing it to expand with inhalation and contract with exhalation. The thoracic diaphragm also separates the organs in the thoracic cavity (chest) and abdominal (belly). By separating these cavities, the important organs like the lungs and heart can function properly in its own compartments. Some organs like the large blood vessels and esophagus (food pipe) pass across the diaphragm between the chest and belly through different openings. In this way the chest and abdomen can communicate with each other only at certain points.

Anatomy of the Diaphragm

The thoracic diaphragm is essentially a large muscle. Like all muscles, it has tendons that attach to the muscles and secure it. The diaphragm is attached to the inside of the ribs, to the back of the breastbone and the spine. The muscle fibers then meet in the middle of the diaphragm at the central tendon. Unlike other muscle tendons, the central tendon does not attach to any bone.

  • Arteries that supply oxygen-rich blood to the diaphragm includes the phrenic arteries from aorta and internal thoracic arteries.
  • Veins drain oxygen-deficient blood from the diaphragm through the phrenic arteries that drain into the suprarenal veins and inferior vena cava.
  • Lymph is emptied from the diaphragm to the diaphragmatic lymph nodes and superior lumbar lymph nodes.
  • Nerves that control the muscle action of the diaphragm are the phrenic nerves (C3 to C5) and sensation is through the phrenic, intercostal (T5 to T11) and subcostal (T12) nerves.

Picture from Wikimedia Commons

(Video) Diaphragm - Definition, Function, Muscle & Anatomy | Kenhub

Shape of the diaphragm

The diaphragm is dome-shaped. The middle part of this dome is depressed just where the heart and its compartment, the mediastinum, are located. This makes the diaphragm a double dome, one on either side. It is the middle of these two side domes that move during respiration (breathing). During inhalation, the muscles contract and the diaphragm becomes almost flat. When the muscles of the diaphragm relax again it rises upwards to once again form the flat-topped dome shape.

Parts of the diaphragm

  • Top of the diaphragm (superior surface) is convex and protrudes into the thoracic cavity.
  • Bottom of the diaphragm (inferior surface) is concave and faces the abdominal cavity.
  • Front of the diaphragm (middle part) is known as the sternal part. It attaches to the back of the breastbone (xiphoid process of the sternum).
  • Back of the diaphragm (middle part) is the lumbar part. It communicates with the first three lumbar vertebrae.
  • Sides of the diaphragm are the remaining parts, excluding the sternal and costal parts, which attach to the back of the last six ribs and its costal cartilages.

There are two bands known as crura (singular ~ crus) that arise from the lumbar vertebrae. There is the right crus and left crus. It runs through to continue into the central tendon and its surrounding muscle fibers. The right and left crus twist along its course to create two openings – one for the aorta and the other for the esophagus.

(Video) Diaphragm Anatomy & Clinical Significance

Openings in the diaphragm

There are several openings in the diaphragm also known as an aperture or hiatus, in the diaphragm. This allows for different structures and organs to run between the thoracic and abdominal cavity since the diaphragm separates these two cavities. There are three large openings and several smaller ones. From front to back is the caval opening, esophageal hiatus and aortic hiatus.

  • Caval opening lies at the level of T8 and T9 vertebrae, slightly to the right of the midline of the diaphragm. The inferior vena cava runs through it, carrying oxygen-deficient blood to the heart. The right phrenic nerve and lymph vessels to the liver also pass through it.
  • Esophageal hiatus is approximately at the level of the T10 vertebra. The esophagus (food pipe) runs through it allowing food from the throat to reach the stomach. The vagal trunks and a few blood and lymphatic vessels also pass through this opening.
  • Aortic hiatus lies approximately at the level of the T12 vertebra. The aorta runs through it carrying oxygen-rich blood to the lower parts of the body. After passing through this opening, the aorta which was known as the thoracic aorta is now referred to as the abdominal aorta.

Picture from Wikimedia Commons

Functions of the Diaphragm


The main function of the diaphragm is as a muscle of respiration, meaning that it aids with breathing. It is aided by other muscles and accessory muscles of breathing when a person experiences shortness of breath. When the diaphragm contracts, the lungs expand and air is inhaled. This occurs because it creates negative pressure within the pleural cavity around the lungs and the elasticity of the lungs allows it to expand thereby drawing in air. When the diaphragm relaxes, it restores the pressure in the pleural cavity and the lungs recoil thereby pushing out air (exhalation). Sudden and repeat contractions of the diaphragm, which are involuntary, leads to hiccups.

(Video) What is the Diaphragm?


The diaphragm also separates the thoracic and abdominal cavities. This allows the heart and lungs to function in its own environment where it can maintain the relative pressure needed for its activity. It also prevents tightly packed abdominal cavity organs from making contact with the important thoracic structures – heart and lungs.

Blood Flow

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(Video) Diaphragm Breathing

When the diaphragm contracts, it pushes down the organs in the abdominal cavity. This action squeezes blood in the inferior vena cava thereby pushing the blood up towards the heart. It is further assisted by the decrease in the pressure within the thoracic cavity as the diaphragm flattens.

Diaphragm Location

The diaphragm is located at the junction of the thoracic and abdominal cavities about halfway down the chest behind the breasts. It has several organs lying immediately above and below it, with a few running through its openings and some even piercing it.

Picture from Wikimedia Commons

(Video) Location of Organs – Anatomy | Lecturio

Position of the diaphragm

The position of the upper parts (dome) of the diaphragm changes with breathing. The periphery of the diaphragm is firmly attached to the breastbone, ribs and vertebrae and its position does not change.

  • Periphery of the diaphragm originates at the level of the 11th and 12th ribs.
  • Center of the diaphragm reaches as high as the 5th rib during expiration.

It is important to remember that the center of the diaphragm is pushed downwards when exhaling. It does not flatten entirely so it does not reach as low as the periphery. Fluid, a mass or other causes of raised pressure in the thoracic or abdominal cavity can push the middle of the diaphragm higher or lower. The liver sitting just under the right diaphragm causes it to be slightly higher than the left diaphragm. Read more on the .

Organs around the diaphragm

The main organs and structures around the diaphragm are as follows :

(Video) Intercostal Muscles - Function, Area & Course - Human Anatomy | Kenhub

  • Above the diaphragm lies the two lungs on either side and the mediastinum housing the heart at the middle.
  • Below the diaphragm is the liver (right), pancreas (around the middle extending to the right), stomach (more towards the left), spleen (left) and kidneys (right and left sides).
  • Front and around the diaphragm lies the breastbone and ribs.
  • Back of the diaphragm lies the vertebral column.


What is the location and function of diaphragm? ›

The diaphragm, located below the lungs, is the major muscle of respiration. It is a large, dome-shaped muscle that contracts rhythmically and continually, and most of the time, involuntarily. Upon inhalation, the diaphragm contracts and flattens and the chest cavity enlarges.

Where is the diaphragm located in the thorax? ›

One can find the origins of the diaphragm along the lumbar vertebrae of the spine and the inferior border of the ribs and sternum. The superior diaphragm origin is continuous from the xiphoid process anteriorly to lower 6 costal cartilages of the thorax laterally and first 2 lumbar vertebrae posteriorly.

Why is the diaphragm located? ›

The diaphragm is a muscle that helps you inhale and exhale (breathe in and out). This thin, dome-shaped muscle sits below your lungs and heart. It's attached to your sternum (a bone in the middle of your chest), the bottom of your rib cage and your spine.

What is the position of diaphragm when we breathe in? ›

When you breathe in, or inhale, your diaphragm contracts and moves downward. This increases the space in your chest cavity, and your lungs expand into it. The muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage both upward and outward when you inhale.

What is the diaphragm function quizlet? ›

What is the diaphragm? A sheetlike dome shaped muscle that sits above the abdominal cavity and below the thoracic cavity and is used for breathing.

Where is the location of the diaphragm quizlet? ›

What is the diaphragm and where is it located? A double-domed (right and left dome) sheet of skeletal muscle, located at the inferior most aspect of the rib cage.

What is the anatomy of the thoracic diaphragm? ›

The diaphragm is an unpaired, dome shaped skeletal muscle that is located in the trunk. It separates the thoracic and abdominal cavities from each other by closing the inferior thoracic aperture. The diaphragm is the primary muscle that is active in inspiration.

Is the diaphragm in the thorax or abdomen? ›

The diaphragm is a thin dome-shaped muscle which separates the thoracic cavity (lungs and heart) from the abdominal cavity (intestines, stomach, liver, etc.).

Is the diaphragm in the front or back? ›

The diaphragm, viewed from above at left with the front of the body on top, is a sheet of muscle and tendon the divides that torso in two. Above is the thorax with the lungs and heart, below is the abdomen, featuring the intestines, stomach, liver, kidneys...

Can you live without a diaphragm? ›

We can't live without one and it's an extremely important part of body. The diaphragm is such a hard working muscle, one takes 23,000 breaths in a day, so if you lived till 80 years old, you will take about 673,000,000 breaths! No wonder it's important to pay attention to this remarkable muscle.

Is the diaphragm behind the heart? ›

It is a complete septum between thorax and abdomen only in mammals. Above the diaphragm and in contact with its superior surface, are the lungs, heart, esophagus, and aorta; below it, and in contact with its inferior surface, are the liver, stomach, and spleen.

Can diaphragm cause breathing problems? ›

Diseases of the diaphragm — the muscle that powers a person's breathing and serves as the barrier between the chest and the abdominal cavity — can cause breathing problems. These conditions are often present at birth or form as a result of injury, accident or surgery.

Is the diaphragm above or below the heart? ›

Location. Many body organs are near the diaphragm. Your heart, lungs, and the upper part of your esophagus (food pipe) are in the thoracic cavity above the diaphragm. Your lower esophagus, stomach, intestines, liver, and kidneys are below the diaphragm, in your abdominal cavity.

Can you breathe from your diaphragm? ›

During diaphragmatic breathing, you consciously use your diaphragm to take deep breaths. When you breathe normally, you don't use your lungs to their full capacity. Diaphragmatic breathing allows you to use your lungs at 100% capacity to increase lung efficiency.

How many major functions does the diaphragm have? ›

The diaphragm helps in the inspiration and expiration of air in and out of the lungs. At the time of inspiration, the diaphragm contracts, increasing the pulmonary volume, thereby reducing the intrapulmonary pressure to less than the atmospheric pressure, and air moves into the lungs.

What is the diaphragm motor function? ›

The diaphragm motor unit remains the final executor of neuromotor control and produces motor force output across a range of ventilatory and higher force, non-ventilatory behaviors.

What nerves control the diaphragm? ›

The phrenic nerve is among the most important nerves in the body due to its role in respiration. The phrenic nerve provides the primary motor supply to the diaphragm, the major respiratory muscle.

Is the diaphragm a bone or muscle? ›

The diaphragm is the major muscle of inspiration, and respiration for that matter, as expiration is a passive movement. When the diaphragm contracts, it descends inferiorly into the abdominal cavity, which results in an increase in intrathoracic volume.

What is the anatomy of the normal diaphragm? ›

The thoracic diaphragm is a dome-shaped septum, composed of muscle surrounding a central tendon, which separates the thoracic and abdominal cavities. The function of the diaphragm is to expand the chest cavity during inspiration and to promote occlusion of the gastroesophageal junction.

What organ is under the diaphragm? ›

The liver is located under the ribs on the right hand side of the body. It lies just below the lungs, under the top of the diaphragm to which it is attached. The diaphragm is the muscle beneath the lungs which regulates our breathing. The liver is partly protected by the rib cage.

Can you control your diaphragm? ›

Diaphragm movement is involuntary. You can't control whether it moves or not, but you can control the abdominal wall, and as you've learned, this needs to be flexible in order for the organs to make room for the diaphragm to move down and allow for the influx of air to create a lovely sound.

Is diaphragm breathing or chest breathing? ›

Diaphragmatic breathing (also called "abdominal breathing" or "belly breathing") encourages full oxygen exchange — that is, the beneficial trade of incoming oxygen for outgoing carbon dioxide. Not surprisingly, this type of breathing slows the heartbeat and can lower or stabilize blood pressure.

What type of muscle is the diaphragm? ›

The mammalian diaphragm muscle is essential for respiration, and thus is one of the most critical skeletal muscles in the human body.

Is the diaphragm one muscle or two? ›

The diaphragm should be viewed as two distinct muscles, crural and costal, which act in synchrony throughout respiration. However, the activities of these two muscular regions can diverge during certain events such as swallowing and emesis.

Can your diaphragm cause back pain? ›

If the diaphragm isn't working properly, it can lead to problems down the kinetic chain, leading to lower back pain.

What is diaphragm made of? ›

The muscles of the diaphragm arise from the lower part of the sternum (breastbone), the lower six ribs, and the lumbar (loin) vertebrae of the spine and are attached to a central membranous tendon.

Does the diaphragm weaken with age? ›

The diaphragm can, over time, become weaker, decreasing the ability to inhale and exhale. This change will only be significant when exercising. Ribcage bones become thinner and change shape, altering the ribcage so that it is less able to expand and contract with breathing.

What happens when your diaphragm is damaged? ›

Symptoms of significant, usually bilateral diaphragm weakness or paralysis are shortness of breath when lying flat, with walking or with immersion in water up to the lower chest. Bilateral diaphragm paralysis can produce sleep-disordered breathing with reductions in blood oxygen levels.

What causes your diaphragm to stop working? ›

[2] There are multiple potential causes for diaphragm dysfunction, including trauma or compression of the phrenic nerve, medications, demyelinating disorders, cervical spinal cord injury, or even congenital causes.

Does a chest xray show your diaphragm? ›

Assessing the diaphragm

This area of the lungs should be checked whenever assessing a chest X-ray. Inferior displacement of the diaphragm is a sign of lung hyperexpansion. Raised position of a single hemidiaphragm may indicate phrenic nerve palsy.

How do you diagnose diaphragm problems? ›

Diagnosing Disorders of the Diaphragm
  1. X-ray: A chest X-ray can identify the presence of blockages or fluids creating pressure.
  2. Computed tomography (CT) scan: This test combines X-ray and computer technology to produce detailed cross-sectional images of your chest cavity.

How do you fix diaphragm problems? ›

A weak or paralyzed diaphragm often goes misdiagnosed and left untreated, causing breathing issues that can worsen over time. While there are several medical treatments options, surgery remains the most effective way to treat a paralyzed or weakened diaphragm.

Can stress affect the diaphragm? ›

What many people do not talk about, is that just like any other muscle, our diaphragm can get tight and restricted. One of the reasons our this muscle gets tight is stress and/or anxiety. With our busy lives, we often experience a lot of this on a day-to-day basis.

What does diaphragm pain feel like? ›

pain in your chest or lower ribs. pain in your side when sneezing or coughing. pain that wraps around your middle back. sharp pains when drawing a deep breath or exhaling.

How does the diaphragm affect the heart? ›

The diaphragm plays a major role in modulating hemodynamics via acting as a respiratory pump that increases systemic venous and lymph return, regulating left ventricular (LV) afterload, modulating pericardial pressure, regulating heart rate variability (HRV), and modulating arterial baroreflex sensitivity.

Which part of the heart is closest to the diaphragm? ›

The inferior or diaphragmatic surface of the heart forms a roughly straight plane or slight concavity that projects to the left and slightly inferiorly to the apex of the heart. It lies superior to the central tendon of the diaphragm and at its lateral projection, the muscular part of the left hemidiaphragm.

How can I improve my shortness of breath when walking? ›

Use Pursed Lip Breathing when walking. Inhale through your nose and exhale through pursed lips. Exhale slowly and comfortably, not forcibly, breathing out twice as long as you breath in. This will keep your breathing slow and restore oxygen to your body more rapidly.

Can you live with a paralyzed diaphragm? ›

You can live with a paralyzed diaphragm. Many patients don't have any symptoms and never need treatment.

What exercises increase lung capacity? ›

Aerobic activities like walking, running or jumping rope give your heart and lungs the kind of workout they need to function efficiently. Muscle-strengthening activities like weight-lifting or Pilates build core strength, improving your posture, and toning your breathing muscles.

Where is diaphragm pain felt? ›

pain in your chest or lower ribs. pain in your side when sneezing or coughing. pain that wraps around your middle back. sharp pains when drawing a deep breath or exhaling.

What is the difference between thoracic and diaphragm? ›

The thorax is inferiorly bounded by the dome-shaped thoracic diaphragm, consisting of muscles and tendons that activate to breathe air in and out of the lungs. The diaphragm separates the thoracic cavity from the abdominal cavity.

What diseases can affect your diaphragm? ›

  • Diaphragm Diseases.
  • Hyperhidrosis.
  • Pleural Diseases.
  • Thoracic Aneurysm. Thoracic Endovascular Aneurysm Repair. Thoracic Aortic Aneurysm.
  • Find a Doctor.
  • Refer to Us.

Can you damage your diaphragm? ›

Heavy impact or a surgical procedure can injure the diaphragm. The resulting pain may be intermittent or constant. Some types of trauma can tear the diaphragm muscle. This is a severe condition called a ruptured diaphragm, which a CT scan or thoracoscopy can diagnose.

How do you know if your diaphragm is messed up? ›

Tight chest. Shortness of breath when lying flat, walking, or immersed in water. Low blood oxygen levels resulting in sleep disorders. Painful sides when sneezing and coughing.


1. Intercostal Muscles - Function, Area & Course - Human Anatomy | Kenhub
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3. Thorax organs - plastic anatomy
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4. Anatomy Thorax Overview - Ribs, Sternal angle, Pleura and Pneumothorax
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6. Muscles of Respiration | Breathing Mechanics | Respiratory Physiology
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