The diaphragm is an involuntary muscle that separates the chest from the abdomen and is significantly involved in breathing. It performs efficient work with every breath, and it is through the diaphragm that humans are able to practice laughter at all.
What is the diaphragm?
The diaphragm is called by medical term diaphragm (not to be confused with contraceptive diaphragm) and describes a plate of muscles and tendons that separates the abdominal cavity (abdomen) from the thoracic cavity (thorax). With an average thickness of about 3 – 5 mm, in humans it performs the function of the main respiratory muscle. When the muscle contracts, the person breathes in. When the diaphragm relaxes, exhalation occurs. The diaphragm is also instrumental in enabling people to laugh. The aorta, esophagus and main veins run through the diaphragm. Nerves and blood vessels are embedded in the muscle-tendon plate. In its function, the diaphragm is unique to humans and mammals. The only exception in the animal kingdom is crocodiles, which, with a connective tissue capsule responsible for respiration, have similar mechanics for inspiration.
Anatomy and structure
The diaphragm, approximately 3 – 5 mm thick, has the shape of a dome-shaped plate encased in a layer of connective tissue. In the abdominal region it is additionally covered by the peritoneum, in the thoracic region by the pleura. In the center of the diaphragm is a usually v-shaped tendon plate in which tightly interwoven tendon fibers are interwoven. The tendon plate is covered by transversely striated muscular domes that find their attachments at the lumbar spine, sternum, and ribs. The diaphragm has three large openings and several small ones. The larger openings denote the aortic slit, the vena cava, and the esophageal slit. While the aortic and esophageal slits are only loosely fixed by connective tissue and thus easily movable, the vena cava is firmly fused to the diaphragm in the form of a ring of connective tissue. Only in this way can the muscles of the diaphragm contract during inhalation without the vena cava collapsing. Blood is supplied by four arteries, and the diaphragm is controlled by the phrenic nerve, which originates from the spinal cord in the 3rd – 5th cervical segment. The diaphragm works silently and is controlled involuntarily.
Functions and tasks
The diaphragm represents itself as the central motor of respiration, promoting more than two-thirds of the total respiratory activity. Contractions of the dome-shaped muscle plate cause the diaphragm to contract and descend, and the process of inhalation occurs. While this increases the volume in the chest cavity, the abdominal space is reduced, and the organs are pushed down into the abdominal cavity. The resulting negative pressure allows air to flow into the lungs, enabling inhalation. Due to the pressure of the diaphragm on the abdominal space, the abdomen bulges forward during inhalation. Thus, in a relaxed position, about 500 ml of air flows into the lungs. The relaxation of the diaphragm, which occurs when it rises again from the abdominal to the thoracic space, triggers exhalation by compressing the lungs. This process, like inhalation, occurs involuntarily and silently. The slackening and lifting of the diaphragm during exhalation allows air to escape from the lungs and the bulging abdomen flattens again. Away from breathing, the diaphragm also plays a significant role in enabling humans to perform the act of laughing. Human laughter, which is physiologically characterized as an increased activity of respiratory movements, is therefore also controlled by the diaphragm. In combination with the abdominal muscles, the diaphragm can build up pressure in the abdominal space without the abdomen bulging outward. This function finds its application in the form of the so-called “abdominal press” during defecation or labor.
Diseases
Because of its efficient and silent work, the diaphragm is often given little importance. It often becomes noticeable only when it is impaired by disease or discomfort. Hiccups, which are triggered by a spontaneous and jerky contraction of the diaphragm, may be mentioned as relatively harmless. Side stitching is felt in the most important respiratory muscle when there is an overload with a simultaneous undersupply of oxygen.If a diaphragmatic hernia is present, the organs move from the abdominal space to the thoracic space. A diaphragmatic hernia can be congenital, but can also develop later in life and usually require surgical treatment. Complaints manifest as inflammation of the esophagus, bloating and nausea, and shortness of breath. As a result of severe chest and abdominal injuries, a tear in the diaphragm (rupture) can occur, which must be surgically repaired as soon as possible due to the high mortality rate. Difficult breathing in combination with a protrusion of the diaphragm into the chest often indicates a diaphragmatic herniation. This is often caused by abnormal changes in the abdominal cavity or lung disease. Pain and limited range of motion of the diaphragm during breathing indicate inflammation of the muscle groups. Functional limitations of the diaphragm sometimes manifest themselves through breathing and vocal problems, since the contraction of the diaphragm simultaneously controls the lowering of the larynx and relieves the voice. Breathing that is too shallow, tension, psychological problems and stress can all lead to a massive restriction of movement.
Typical and common disorders
- Hiatal hernia
- Belching
- Hiccups
- Diaphragmatitis
