Diaphragm

Synonyms

medical: diaphragm

Definition

The diaphragm is a peculiarity of mammals. It is a three to five millimeter thick, dome-shaped, muscular-tendon plate that separates the chest (thorax) from the abdomen and represents the most important respiratory muscle. Structure: The diaphragm can be divided tissue-technically (histologically) into two parts.

The muscular parts originate from the origins of the thoracic musculature at the lower thoracic wall. They unite in a central tendon field (Centrum tendineum), which represents the sinewy part. For orientation, the muscular part of the diaphragm is divided into three sections: The muscular part of the pars sternalis originates from the posterior surface of the xiphoid process (Processus xiphoideus) and the rectus sheath.

The pars costalis originates from the cartilage of the lower six ribs at the costal arch. The medial part (crus mediale) of the pars lumbalis originates from the lumbar vertebral bodies 1-3 and their intervertebral discs; the lateral part (crus laterale) originates from the second lumbar vertebral body, the 1st lumbar vertebrae, among others. Tendon arch of the psoasarcade (arcade-shaped tendon strip of the Musculus psoas major, Ligamentum mediale), the 2nd tendon arch of the quadratus arcade (arcade-shaped tendon strip of the Musculus quadratus lumborum, Ligamentum laterale) and the costal process of the second lumbar vertebral body to the tip of the 12th rib.

The different muscular parts unite on both sides in a dome-shaped manner to form a sinewy center and thus form the boundary between the abdominal and thoracic cavity. Thus, it has close neighborly relations to organs of both body cavities. On the upper side, in the thoracic cavity, the right lobe of the lung adjoins on the right side and on the left side the left lobe of the lung and the pericardium, which is fused with the sinewy center of the diaphragm.

At the bottom of the abdominal cavity, the liver (with its area nuda fused to the diaphragm) and the right kidney are adjacent to the diaphragm on the right side and the left liver lobe, gastric fundus, spleen and left kidney on the left side. Between the muscle parts there are triangular triangles filled with little connective tissue: the trigonum sternocostale (central, so-called Larey’s cleft) in the pars sternalis and the trigonum lumbocostale (both sides, so-called Bochdalek triangle).

  • Middle part, behind the sternum = Pars sternalis
  • Both sides facing the ribs = Pars costalis
  • Back part, facing the back = Pars lumbalis, with right and left thigh (Crus dexter and Crus sinister).

Passage of the diaphragm/diaphragmatic gaps:The diaphragm has openings for the passage of conducting pathways and organ connections.

The following overview gives a general idea. Diaphragmatic gap: Foramen venae cavae (at the level of the 8th diaphragmatic vertebrae) Hiatus oesophageus (at the level of BWK 10) Hiatus aorticus (at the level of BWK 12/LWK 1) Gaps in the crus medial gaps between the crus medial and lateral trigonum sternocostal vascular supply of the diaphragm: Above the diaphragm, the following arteries supply the diaphragm with oxygen-rich blood: arteria pericardiacophrenica dexter und sinister, which originate on both sides of the arteria thoracica interna dexter und sinister, and arteria musculophrenica dexter und sinister, which continue the course of the arteria thoracica interna. A branch of the thoracic aorta, the arteria phrenica superior, also contributes to the supply.

Below the diaphragm, a branch of the abdominal aorta, the arteria phrenica inferior, supplies the diaphragm. The venous outflow is via veins of the same name. The diaphragm is nervously supplied by the phrenic nerve from the cervical plexus.

It receives parts from the spinal cord segments C3-5 (the “C” stands for cervical, i.e. located in the neck area). An old saying for this is: “Three, four, five, keeps the diaphragm alive!

  • Penetrating structures:Vena cava inferiorRamus phrenicoabdominalis of the right phrenic nerve
  • Inferior vena cava
  • Ramus phrenicoabdominalis of the right phrenic nerve
  • Inferior vena cava
  • Ramus phrenicoabdominalis of the right phrenic nerve
  • Penetrating structures: Oesophagus and trunci vagales anterior and posterior (parasympathetic nerve fibers)
  • Oesophagus and on it lying
  • Trunci vagales anterior and posterior (parasympathetic nerve fibers)
  • Oesophagus and on it lying
  • Trunci vagales anterior and posterior (parasympathetic nerve fibers)
  • Penetrating structures: Aorta descendensDuctus thoracicus (“thoracic milk duct”, lymph vessel)
  • Aorta descendens
  • Ductus thoracicus ( breast milk duct, lymph vessel)
  • Aorta descendens
  • Ductus thoracicus ( breast milk duct, lymph vessel)
  • Penetrating structures:Right: Vena azygosLeft: Vein hemiazygosNervi splanchnici
  • Right: Vena azygos
  • Left: vein hemiazygos
  • Nervi splanchnici
  • Right: Vena azygos
  • Left: vein hemiazygos
  • Nervi splanchnici
  • Penetrating structures:Truncus sympathicus
  • Sympathetic trunk
  • Sympathetic trunk
  • Penetrating structures:Arteria and vena thoracica interna/epigastrica superior
  • Arteria and vena thoracica interna/epigastrica superior
  • Arteria and vena thoracica interna/epigastrica superior

Read next article in this series:

All articles in this series:

  1. Diaphragm
  2. Functional and topographic anatomy of the diaphragm
  3. Pain in the diaphragm
  4. Diaphragmatic spasm
  5. Train diaphragm
  6. Summary