The diaphragm is a thin muscular tendinous septum that separates the chest cavity from the abdominal cavity and allows the structures which pass between the chest and abdomen.
It is the most important muscle for respiration.
It is dome shaped and consists of two parts which are
1. Peripheral muscular part
2. Centrally placed tendon


Diaphragm arises from three parts which are

1. Sternal part

The sternal part arises from the xiphoid process of the sternum.

2. A Costal part

The costal part of diaphragm arises from the surface of the lower six ribs and their costal cartilages.

3. Vertebral part

The vertebral part of the diaphragm arises from the crura and arcuate ligaments.

Crura from which diaphragm arises are the right crus and left crus. Right crus arises from the first three lumbar vertebrae and intervertebral discs while the left crus arise from the first two lumbar vertebrae and intervertebral discs.
Lateral to crura diaphragm arises from arcuate ligament which is medial and lateral arcuate ligaments.
Medial arcuate ligament extends from 2nd lumbar vertebrae to the transverse process of the 1st lumbar vertebrae.
Lateral arcuate ligament extends from the transverse process of 1st lumbar vertebrae to the lower border of the 12th rib.

Central tendon

The diaphragm is inserted into the central tendon and its upper surface of the tendon is partially fused with the fibrous pericardium.

Shapes of Diaphragm

If we see the diaphragm from the front it curves into right and left domes. The right dome reaches to the upper border of the 5th rib while the left dome reaches to the lower border of the 5th rib.
These right and left dome supports the right and left lungs.
The central tendon of Diaphragm lies at the level of the xiphisternal joint which is a joint between the sternum and xiphoid process.
Central tendon supports the heart.
It is lower when the person is sitting or standing.
The Diaphragm is higher in the supine position.
If we see the diaphragm from the side it gives the appearance of an inverted j. which has a long limb and a short limb. Long limb extends from the vertebral column while the short limb extends to the xiphoid process.

Nerve supply

it receives both motor and sensory nerve supply.

Sensory nerve supply

The central part receives sensory nerve supply from the phrenic nerve while the peripheral part receives sensory nerve supply from the lower six intercostal nerves.

Motor nerve supply

It receives motor nerve supply from the right and left phrenic nerves.

The action of the diaphragm

When the diaphragm contracts it pulls down its central tendon due to which vertical diameter of the thorax increases.

Functions of the diaphragm

1. On contraction, it pulls down its central tendon due to which vertical diameter of the thorax increases so it is an important muscle for inspiration.
2. Contraction of it assists the contraction of the anterior abdominal wall muscles due to which intra-abdominal pressure rises which is helpful in micturition, defecation, and parturition.
3. When a person takes a deep breath and holds it this muscle increases the intra-abdominal pressure to such extent that it supports the vertebral column and prevent flexion.
4. It also acts as a thoracoabdominal pump because it increases the intra-abdominal pressure and lowers the intra-thoracic pressure due to which blood is compressed in the inferior vena cava and forces it upward into the right atrium.


There are three main openings in this muscle which are
1. Aortic opening
2. Esophageal opening
3. Caval opening


Aortic opening of the diaphragm

It lies anterior to the body of the 12th thoracic vertebrae between crura.
the structures which pass through the aortic opening are
Thoracic duct
Azygous vein

Esophageal opening of the diaphragm

Esophageal opening lies at the level of 10th thoracic vertebrae in a sling of muscle fibers.
the structures which pass through the esophageal opening are
right vagus nerve
left vagus nerve
esophageal branches of left gastric vessels

Caval opening of the diaphragm

It lies at the level of the 8th thoracic vertebrae in the central tendon.
The structures which pass through caval opening are
Inferior vena cava
terminal branches of the right phrenic nerve.

Diaphragm conditions

Diaphragm condition or the conditions that involve or affect the diaphragm.

Hiatal hernia

This hernia happens when the stomach upper part bulges through the esophageal opening.

1. Age-related changes
2.  Injuries
3.  Birth defects
4.   Chronic pressure on surrounding muscles
5.  Common in people over the age of fifty.
6.  Obesity

1. Heartburn
2.  Acid reflux
3.  Trouble in swallowing
4.   Chest pain

Larger and severe hiatal hernias require surgery but smaller and mild hiatal hernias are manageable with medications.

Diaphragmatic hernia

This condition occurs when one of the organs in the abdomen bulges out into the chest through the diaphragmatic opening. Sometimes it is present at birth and is known as a congenital diaphragmatic hernia. Injuries can cause this condition. The diaphragmatic hernia that is caused by the injuries is known as acquired diaphragmatic hernia.

1. difficulty in breathing
2.  Rapid breathing
3.  Rapid heart rate
4.   Bowel  sound in the chest

Both congenital and acquired diaphragmatic hernias need immediate surgery in which abdominal organs are removed from the chest cavity and diaphragm is repaired.

Cramp and spasm

Diaphragmatic cramp or spasm can cause pain in the chest and also cause the shortness of the breath and Due to the above symptoms sometimes it’s can be mistaken for a heart attack.

1. chest pain
2.  Shortness of breath
3.   Sweating
4.   Anxiety
5.   Cannot take a full breath

Diaphragmatic flutter

It is a rare condition that is often mistaken for a spasm. People who suffer from the diaphragmatic flutter feel the flattering as a pulsing sensation in the abdominal wall.

1. pulsing sensation in the abdominal wall
2.  Chest tightness
3.   Chest pain
4.   Abdominal pain

Phrenic nerve damage

Various factors can damage the phrenic nerve that includes
1. injuries
2.  Surgeries
3.  Cancer in the lungs
4.  Cancer in nearby  lymph nodes
5.   Autoimmune diseases
6.   Multiple sclerosis
7.   Viral illnesses

Phrenic nerve damage can cause
1. dysfunction of the diaphragm
2.  Paralysis of the diaphragm

This condition does not always cause symptoms but below are some of the possible symptoms

1. Shortness of breath
2.  Morning headaches
3.   Trouble sleeping
4.    Chest pain

Healthy diaphragm

If you want to maintain a healthy diaphragm then follow the following steps

1.  Avoid foods that trigger heartburn
2.   Avoid foods that trigger acid reflux
3.   Eat less portion of food at a time
4.   Stretching and warming before exercise
5.  Regular exercise in the limit.

Categories: human thorax