Aortic opening of the diaphragm. An inconspicuous muscle, the diaphragm - why work on it? Crossing of the legs of the diaphragm, or not

Thoracic diaphragm, diaphragma, m. phrenicus, in Greek “septum” διάφραγμα, as we of course remember, is a muscular-tendon septum and separates the thoracic and abdominal cavities.

Functions of the diaphragm in normal physiology

• Separates the chest and abdominal cavities as the διάφραγμα “septum”.
• Unites the thoracic and abdominal cavities. Osteopathic dysfunctions of the organs of the abdominal and thoracic cavities, striving for adaptation, almost always involve the diaphragm and change its shape and mobility.
• Support function. The diaphragm has many connective tissue connections with internal organs.
• External breathing together with the intercostal muscles. Diaphragm — the most important respiratory muscle (and cranial specialists will think about the PDM).
• “Second heart”: when inhaling, the diaphragm contracts and its dome lowers. At the same time, the pressure in the chest decreases, which contributes to the expansion of the lumen of the vena cava and venous inflow into the right atrium.
  On the other side of the diaphragm — In the abdominal cavity, during inhalation, pressure increases. Increasing pressure on the internal organs facilitates the outflow of venous blood from them. The inferior vena cava also feels the increase in intra-abdominal pressure and more easily gives venous blood up behind the diaphragm to the heart.
• Lymphatic drainage. The diaphragm functions as a pump for lymph in the same way as for venous return.
• Participation in activities digestive system. Rhythmic contractions of the diaphragm have a mechanical effect on the intestines and promote the outflow of bile.

Anatomy of diaphragms

Tendon center of the diaphragm

Rice. Tendon center of the diaphragm and the course of the fibers.Tendon center green in color, like a trefoil. In Italian anatomy, the superior and inferior semicircular ligaments around the opening of the inferior vena cava are also distinguished.

In a child, the tendon center is less pronounced — predominates in the diaphragm muscle part. Over the years, the muscle fibers in the diaphragm become smaller, and the tendon center increases.

It is also worth noting that the tendon center has great strength and low extensibility. The force lines originate from the tendon center and run radially along the muscle fibers of the muscular part of the diaphragm.

Muscular part of the diaphragm

The muscle bundles of the diaphragm extend radially from its tendon center and reach the lower aperture (exit) from chest and are attached to it. Thus, the diaphragm attachment — this is the entire osteochondral lower aperture of the chest: the lower 6 pairs of ribs, the xiphoid process, the thoracolumbar junction of the spine. The legs of the diaphragm extend to L4.

The entire muscular part (pars muscularis) of the diaphragm, depending on the places of attachment of its bundles, is divided into sternal part (pars sternalis), costal part (pars costalis), And lumbar part (pars lumbalis).

Rice. Diaphragm parts. The sternal part is highlighted in red, the costal part in blue, and the lumbar part in yellow. The tendon center of the diaphragm is pale turquoise.

Sternal part of the diaphragm smallest. It is usually represented by one (less often two) muscle bundle, which starts from the xiphoid process and the posterior layer of the fascia of the rectus abdominis muscle and follows dorsocranial to the anterior lobe of the tendon center of the diaphragm. In 6% of cases, the sternal part of the diaphragm is completely absent. Then in its place only a plate of diaphragmatic fascia and peritoneum remains.

Costal part of the diaphragm attached to the inner surface of the cartilages of the lower six pairs of ribs (VII - XII). This is the widest part of the aperture. The attachment of the left part is usually lower than the right one. At the point of attachment to the ribs, the muscle bundles of the diaphragm alternate with bundles of the transverse abdominal muscle.

The length of the muscle fibers of the costal part of the diaphragm is related to the width of the chest. Usually the distance from the costal arch to the tendon center is from 1 to 2-2.5 cm.

Lumbar part of the diaphragm the longest and also remarkable for the presence of legs — separate attachments to the skeleton.

Diaphragm legs

In addition to the muscular legs, the lumbar part of the diaphragm also has other more rigid connective tissue attachments to the transverse processes of the first (second) lumbar vertebra and to the twelfth rib. Between these diaphragm attachments connective tissue The diaphragm is stretched in the form of arches, and under these arches there are all sorts of vital structures.

Rice. The legs of the diaphragm and the arches between them. In the middle between the muscular legs of the diaphragm (1st right leg) on ​​the anterior surface of the spine runs the aorta (6). Between the muscular pedicle (1) and the attachment of the diaphragm to the transverse process of the lumbar vertebra (2), the free edge of the diaphragm is stretched in the form of an arch or arc. This is the medial arcuate ligament (4). Lateral to the attachment to the transverse process there is another attachment of the diaphragm - to the twelfth rib (3). The stretched edge of the diaphragm from the transverse process to the twelfth rib forms another arch - the lateral arcuate ligament (5).

Lateral arcuate ligament (lig. arcuatum laterale).

Also called the lateral lumbocostal arch, or arcus lumbocostalis lateralis. Throws between the XII rib and the transverse process of the first or second lumbar vertebra.

Under the lateral arcuate ligament pass:

• quadratus lumborum muscle (m. quadratus lumborum),
• sympathetic trunk.

Medial arcuate ligament (lig. arcuatum mediale, or arcus lumbocostalis medialis).

• psoas major muscle (m. psoas major),
• large and small splanchnic nerves (nn. splanchnici),
• azygos vein on the right,
• hemizygos vein (v. hemiazygos), left.

Aperture holes

Aortic orifice(hiatus aorticus) is located to the left of the midline. Between the crura of the diaphragm and the spine (posteriorly) there remains a triangular space through which the aorta and the thoracic lymphatic duct pass. According to a number of researchers, in men aged 20 to 40 years, the diameter of the aortic opening is from 2.0 to 2.5 cm, over 40 years old - from 2 to 3.5 cm. In women, such expansion of the aortic opening was not detected; they initially have a freer opening of the aorta: about 2.7 cm.

In the area of ​​the aortic opening, the wall of the thoracic lymphatic duct is usually fused with the right leg of the diaphragm. This ensures the movement of lymph under the rhythmic influence of the pulsating diaphragm.

Esophageal opening(hiatus oesophageus). Rising higher above the aortic opening to the tendinous center, the crura of the diaphragm form the esophageal opening, through which the esophagus and vagus nerves pass. The esophageal opening of the diaphragm is located to the left of the midline.

Rice. The diagram shows the levels of the diaphragm holes. At the height of Th8 there is the opening of the inferior vena cava, at the level of Th10 - the esophageal opening, at the level of Th12 - the opening of the aorta.

Are the legs of the diaphragm crossed or not?

But we can learn that a number of respected anatomists have conducted research on the opening of the esophagus. And these respected people (Roy Camille, B.V. Petrovsky, N.N. Kanshin and N.O. Nikolaev) as a result of their work found several types of “branching” of the legs of the diaphragm.

The results are very surprising for all-feeling osteopaths. The most common option is the formation of both the aortic and esophageal openings in bundles only right leg without any crossovers. The esophageal opening is almost always limited by muscle bundles emanating only or almost only from the right leg of the diaphragm.

But there are also rare forms of formation of the esophageal opening:

a) the esophageal opening is formed by mutually intersecting bundles of the right and left medial legs in the form of a number 8, thus forming the hiatus aorticus and hiatus oesophageus. Previously, such formations of the esophageal and aortic openings were mistakenly considered classic, i.e., the most common;

b) formation of the esophageal opening only due to one left inner leg of the diaphragm;

c) when there is one common opening for both the aorta and the esophagus. Such a picture is rare.

Rice. The figure shows options for the “branching” of the diaphragm legs. The frequency of their occurrence is indicated under the types.

The esophagus is connected to the edges of the esophageal opening of the diaphragm by loose connective tissue. This loose connection allows the esophagus to maintain mobility in relation to the diaphragm and make sliding movements.

Fascia of the diaphragm
The diaphragm on the thoracic and abdominal surfaces is covered with fascia. Outside, on the fascia lies the connective tissue of the subpleural tissue above and the subperitoneal tissue below. This connective tissue tissue forms the basis for the serous parietal layer of the peritoneum on the side of the abdominal cavity, and the parietal layer of the pleura and cardiac bursa on the side of the thoracic cavity.

Rice. The edge of the diaphragm, the pleural angle, the kidney and their fascia. 1-pleura; 2-diaphragm; 3-fascia diaphragmatica; 4-liver; 5-adrenal gland; 6-right kidney; 7-fascia prerenalis; 8-peritoneum; 9-fascia Toldti; 10-paraureterium; 11-vasa iliaca communia; 12 am. iliacus; 13-fascia iliaca; 14-aponeurosis m. transversi abdominis (deep leaf of fascia thoracolumbalis); 15-m. erector spinae; 16- fascia retrorenalis; 17-m. quadratus lumborum; 18-arcus lumbocostalis lateralis; 19-fascia thoracolumbalis.

Literature:

Maksimenkov A.N. Surgical anatomy of the abdomen 1972.

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Diaphragm—its own mobility and embryogenesis.

As we know and feel, the thoraco-abdominal diaphragm has complex mobility of its own. One of the most interesting models is the connection between motility, or the intrinsic mobility of organs, and embryogenesis. It is assumed that the organ in its mobility (motility) repeats embryonic movements and movements. Let's try to consider the embryogenesis of the diaphragm and its correspondence to its own fluid mobility.

Rice. The arrows indicate the movements of parts of the growing diaphragm.

Diaphragma

Starting around the circumference of the lower opening of the chest (apertura thoracis inferior), it protrudes dome-shaped into the chest and separates chest cavity from the abdominal cavity. Along the periphery, the diaphragm is formed by a thin muscle plate, which from its beginning is directed upward and inward and ends in the middle with a tendon center (centrum tendineum), the right half of which rises in front to the level of the IV, and the left half to the level of the V rib. Adjacent to the diaphragm above are: fascia phrenico-pleuralis (part of the fascia endothoracica), subpleural tissue and (on most of the surface) the diaphragmatic pleura, as well as (on a smaller part of the surface) the pericardium.

Adjacent to the diaphragm below are the fascia endoabdominalis, preperitoneal tissue and parietal peritoneum. The latter covers the diaphragm, with the exception of those areas where the retroperitoneal tissue is adjacent to it with the kidneys, adrenal glands, large vessels located in it next to the diaphragm and where between the sheets of lig. coronarium hepatis the liver is adjacent to the diaphragm.

The muscular section of the human diaphragm consists of pars stemalis, pars costalis and pars lumbalis. The sternal part of the diaphragm starts from back surface xiphoid process and sometimes (in 6% of cases) may be completely absent. The most extensive part of the diaphragm is the costal part. It starts from the inner surface of the 6 lower ribs, departing from the edge of the costal arch by 1-2.5 cm. The lumbar part of the diaphragm is the thickest. It consists of the right and left legs (crus dextrum and crus sinistrum). The medial parts of both legs start from the anterior and lateral surfaces of the bodies of the I-IV lumbar vertebrae, go up and forward and connect with each other above the aorta, forming the hiatus aorticus. Then towards the left and up medial bundles They diverge again, forming the esophageal opening of the diaphragm (hiatus oeso-phageus), and unite near the tendon center. Wide lateral muscle bundles of the legs of the lumbar part of the diaphragm begin from lig. arcuatum mediale and lig. arcuatum laterale. Through the hiatus aorticus, which is limited by body XII thoracic vertebra and the tendon semi-ring of the right and left legs of the diaphragm, passes the aorta and the thoracic duct located behind and medially from it. The walls of the aorta and thoracic duct fuse with the edges of the opening. The esophagus and the anterior and posterior trunks of the vagus nerves pass through the hiatus oesophageus, located anterior and superior to the aortic opening. The distance from the hiatus aorticus to the hiatus oesophageus is on average 2-4 cm with fluctuations from 1 to 6 cm. Medially, through the gaps in the right and left legs of the diaphragm, the greater and lesser splanchnic nerves penetrate from the chest cavity into the abdominal cavity, and in the opposite direction to the right - azygos and on the left - semi-zygos veins. The sympathetic trunk passes between the lateral and medial parts of the right and left crura lumbar region diaphragm respectively on each side. The inferior vena cava enters the chest cavity through the foramen venae cavae, located in the tendon center. The walls of the hole and the vein are firmly fused to each other. Between the sternum and costal parts of the diaphragmatic muscle in front and between the costal and lumbar parts at the back, there are unstable triangular-shaped areas that are devoid of muscle tissue and, due to their weakness, can become a site for the formation of diaphragmatic hernias and the spread of suppurative processes.

Arteries. From above, the following penetrate the diaphragm: in front - branches of a. musculophrenicae and a. pericardiacophrenicae (both from the inner thoracic artery), from behind - aa. phrenicae superiores (from the thoracic aorta). The main vessel supplying the diaphragm is a. phrenica inferior. It starts from the front surface abdominal aorta directly at the lower edge of the tendon semi-ring of the legs of the diaphragm and, heading forward and upward, soon divides into right and left branches, which spread over the entire lower surface of the diaphragm (Fig. 42). The right and left branches of the phrenic artery can independently arise from the abdominal aorta, like its paired parietal branches.

Rice. 40. Diaphragm from the side of the pleural cavities and the pericardial cavity. View from above.

Lymphatic drainage from the diaphragm is complex and is directed upward, into the sternal The lymph nodes and into the nodes of the anterior and posterior mediastinum, and down into the nodes of the retroperitoneal space, located at the upper edge of the pancreas, at the gates of the spleen and liver, at the cardiac part of the stomach and at the inferior vena cava.

Rice. 41. Diaphragm after removal of the pleura and pericardium. Vessels and nerves of the diaphragm. View from above

Rice. 42. Diaphragm from the abdominal cavity. Bottom view

Innervation. Right and left pp. phrenici begin from the cervical plexus (Cm-Cv), penetrate the chest cavity and, passing through the anterior mediastinum, enter the diaphragm and innervate each half of the muscle. The right n. phrenicus approaches the tendinous center at the level and lateral to the inferior vena cava and divides into two branches. The left one approaches the diaphragm somewhat more laterally and anteriorly than the right nerve, and at the level of the apex of the heart it enters the muscular part of the diaphragm, dividing into 5-6 branches. To the lower surface of the diaphragm from the celiac plexus along a. phrenica inferior and its branches can penetrate a single branch or a number of branches forming the diaphragmatic autonomic plexus. The right part of this plexus is often well defined, contains from two to four ganglia phrenica and forms a constant connection with the right phrenic nerve in the lumbar part of the diaphragm. The left part of the plexus is often absent, has no ganglia, and its connections with the phrenic nerve are found only on individual drugs. Sensitive branches from the VII-XII intercostal nerves penetrate into the peripheral parts of the diaphragm to a small depth together with the vessels.

(diaphragma, s.m. phrenicus) - a movable muscle-tendon septum between the thoracic and abdominal cavities. The diaphragm has a dome shape due to its position internal organs and the difference in pressure in the chest and abdominal cavities. The convex side of the diaphragm is directed into the chest cavity, and the concave side is directed down into the abdominal cavity. The diaphragm is the main respiratory muscle and the most important body abdominal press. The muscle bundles of the diaphragm are located along the periphery, have a tendon or muscle origin on the bony part of the lower ribs or costal cartilages surrounding the lower aperture of the chest, on the posterior surface of the sternum and lumbar vertebrae. Converging upward, towards the middle of the diaphragm, the muscle bundles pass into the tendon center (centrum tendineum). According to the beginning, the lumbar, costal and sternal parts of the diaphragm are distinguished. The muscle bundles of the lumbar part (pars lumbalis) of the diaphragm begin on the anterior surface of the lumbar vertebrae, forming the right and left legs (crus dextrum et crus snistrum), as well as on the medial and lateral arcuate ligaments. Medial arcuate ligament(lig. arcuatum mediale) is stretched over the psoas major muscle between the lateral surface of the 1st lumbar vertebra and the apex of the transverse process of the 2nd lumbar vertebra. Lateral arcuate ligament(lig. arcuatum laterale) runs transversely in front along the square mouse of the lumbar region and connects the apex of the transverse process of the 11th lumbar vertebra with the XII rib.

The right leg of the lumbar part of the diaphragm is more developed and begins on the anterior surface of the bodies of the I-IV lumbar vertebrae. The left leg originates on the first three lumbar vertebrae. The right and left legs of the diaphragm below are woven into the anterior longitudinal ligament of the spine. At the top, the muscle bundles of these legs intersect in front of the body of the first lumbar vertebra, limiting the aortic opening (hiatus aorticus). The aorta and thoracic (lymphatic) duct pass through this opening. The edges of the aortic opening of the diaphragm are limited by bundles of fibrous fibers - these are median arcuate ligament(lig. arcuatum medianum). When the muscle bundles of the legs of the diaphragm contract, this ligament protects the aorta from compression. Above and to the left of the aortic opening, the muscle bundles of the right and left legs of the diaphragm again cross, and then diverge again, forming the esophageal opening (hidtus esophageus). Through this opening, the esophagus, together with the vagus nerves, passes from the chest cavity to the abdominal cavity. Between the muscle bundles of the right and left legs of the diaphragm pass the corresponding sympathetic trunk, the greater and lesser splanchnic nerves, as well as the azygos vein (right) and semi-gypsy vein (left).

On each side, between the lumbar and costal parts of the diaphragm, there is a triangular-shaped area devoid of muscle fibers, the so-called lumbocostal triangle. Here, the abdominal cavity is separated from the thoracic cavity only by thin plates of intra-abdominal and intrathoracic fascia and serous membranes (peritoneum and pleura). Diaphragmatic hernias can form within this triangle.

The costal part (pars costalis) of the diaphragm begins on the inner surface of the six to seven lower ribs with separate muscle bundles that are wedged between the teeth of the transverse abdominal muscle.

The sternal part (pars sternalis) of the diaphragm is the narrowest and weakest, beginning on the posterior surface of the sternum.

Between the sternum and the costal parts of the diaphragm there are also triangular sections - sternocostal triangles, where, as noted, the pectoral fascia and abdominal cavities are separated from each other only by the intrathoracic and intra-abdominal fascia and serous membranes (pleura and peritoneum). Diaphragmatic hernias can also form here.

In the tendon center of the diaphragm on the right there is an opening for the inferior vena cava (foramen venae cavae), through which this vein passes from the abdominal cavity to the thoracic cavity.

Function of the diaphragm: when the diaphragm contracts, its dome flattens, which leads to an increase in the thoracic cavity and a decrease in the abdominal cavity. When contracted simultaneously with the abdominal muscles, the diaphragm helps to increase intra-abdominal pressure.

Diaphragm diseases

Damage to the diaphragm can occur with penetrating wounds of the chest and abdomen and with closed trauma, mainly during transport or catatrauma (fall from a height). Against the background of this injury, damage to the diaphragm is not always determined clinically, but in all cases of damage to the chest and abdomen, the diaphragm must be examined without fail, and it must be remembered that in 90-95% of cases closed injury the left dome is damaged.

The most common pathology of the diaphragm is hernia. Based on location, hernias of the dome of the diaphragm and the esophageal opening are distinguished. It is extremely rare to have hernias of the fissure of the sympathetic trunk, the inferior vena cava, or the foramen of the intercostal nerve, but they do not give a clinical picture and more often serve as an operational finding. Based on their origin, hernias are divided into congenital and acquired, with a missed rupture. Clinical manifestations depend on the size of the hernial orifice and the tissues emerging through them into the chest cavity. For small sizes and prolapse of only the omentum clinical manifestations there may not be a hernia. The most acute strangulated hernias domes of the diaphragm (hiatal hernias are never strangulated): sudden attack sharp pain in the epigastrium and chest, there may even be painful shock, palpitations, shortness of breath, vomiting, and if the intestine is strangulated - signs of intestinal obstruction.

Sliding hernias of the dome of the diaphragm, most often of traumatic origin, but can also form with underdevelopment of the diaphragm with localization in the region of the costo-lumbar triangle, usually on the left (Bogdalek's hernia), are accompanied by two syndromes: gastrointestinal and cardio-respiratory or a combination thereof. Gastrointestinal syndrome is manifested by pain in the epigastrium and hypochondrium (usually in the left), chest, radiating upward - to the neck, arm, under the shoulder blade, emaciation, vomiting, sometimes with an admixture of blood, paradoxical dysphagia (solid food passes freely, liquid food is retained followed by vomiting ). When prolapse into the chest cavity of the stomach there may be stomach bleeding. Cardiorespiratory syndrome is manifested by cyanosis, shortness of breath, palpitations, which intensify after eating, physical activity, in a tilted position. On physical examination of the chest, there may be a change in percussion sound (tympanitis or dullness), weakening or absence of breathing in the lower lobes, bowel sounds, etc. may be detected.

Diaphragmatic hernias are accompanied by pain and burning in the epigastrium and behind the sternum, heartburn, belching of air, regurgitation, and sometimes dysphagia. Symptoms intensify after eating, in a horizontal position, or bending the body. Sen's syndrome may develop: a combination of hiatal hernia, cholelithiasis and diverticulitis of the colon. Relaxation of the diaphragm can rarely occur: congenital, caused by underdevelopment of muscles, and acquired, formed when inflammatory processes in the diaphragm, damage to the phrenic nerve. Accompanied by pain in the epigastrium and hypochondrium, shortness of breath, palpitations, a feeling of heaviness after eating, belching, nausea, constipation, and weakness. Patients have frequent recurrent pneumonia of the lower lobes.

The examination complex should include: x-ray of the lungs and abdomen, if indicated, a study is performed with contrasting the stomach and intestines with barium suspension and pneumoperitoneum (carefully, with a ready-made kit for puncture of the pleural cavity or thoracentesis), laparoscopy or thoracoscopy with artificial pneumothorax, FGS. The purpose of the study is not only to establish the pathology of the diaphragm, but also to conduct differential diagnosis with tumors of the esophagus, tumors and cysts in the liver, spleen.

Tactics: treatment is carried out surgically, the examination is complex, so the patient should be hospitalized in the thoracic department, or less often in the abdominal surgery department.

The diaphragm (diaphragma) (Fig. 167) is an unpaired muscular aponeurotic plate separating the thoracic and abdominal cavities. On the side of these cavities, the diaphragm is covered with thin fascia and serous membranes. The diaphragm has the shape of a vault, convexly facing the chest cavity, which is due to high pressure in the peritoneal cavity and low - in the pleural cavity.

The muscle bundles of the diaphragm are radially oriented towards its center and, at the point of origin, are divided into lumbar, costal and sternal parts.

Lumbar part(pars lumbalis) the most complex. It consists of three paired legs: medial (crus mediate), intermediate (crus intermedium) and lateral (crus laterale).

The medial leg, paired, right, starts from the anterior surface of the lig. longitudinale anterior of the spine at the level of the III-IV lumbar vertebrae, the left one is shorter and is formed at the level of the II lumbar vertebra. The muscle bundles of the right and left legs rise and at the level of the first lumbar vertebra partially intersect each other, forming the aortic opening (hiatus aorticus) of the diaphragm for the passage of the aorta and the beginning of the thoracic lymphatic duct. The edge of the aortic opening has a tendon structure, which protects the aorta from compression when the diaphragm contracts. The muscle bundles 4-5 cm above and to the left of the aortic opening intersect again, forming an opening for the passage of the esophagus (hiatus esophageus), the anterior and posterior trunks of the vagus nerves. Muscle bundles limit this opening and perform the function of the esophageal sphincter.

The intermediate leg, the steam room, begins in the same place as the previous one, rises along the lateral surface of the vertebrae somewhat lateral from the medial leg. Above the aortic opening, the bundles diverge radially. Between the medial and intermediate legs there is a slight gap on the right for the passage of the nn. splanchnici et v. azygos, left - nn. splanchnici et v. hemiazygos.

The lateral leg, paired, the largest of all three legs, originates from two arches (arcus medialis et arcus lateralis), representing thickened fascia, thrown respectively through m. psoas major and m.quadratus lumborum. The cms mediale is stretched between the body of the 1st or 2nd lumbar vertebra and the transverse process of the 1st vertebra. Crus laterale is longer, starts from the apex of the transverse process of the 1st lumbar vertebra and attaches to the 12th rib. The lateral leg, starting from these arches, is initially fused with the posterior part of the chest, and then deviates forward and fan-shapedly scatters in the dome. A narrow gap is formed between the lateral and intermediate legs for the passage of the truncus sympathicus.

Rib part the steam room is the most extensive section of the diaphragm. It begins with teeth from the inner surface of the cartilages of the VII-XI ribs. The muscle bundles pass into the tendon center of the diaphragm. At the junction of the lateral leg, lumbar and costal parts there are triangular spaces (trigonum lumbocostal), devoid of muscle bundles and covered with pleura, as well as peritoneum and thin fascia.

Sternal part The diaphragm begins from the inner surface of the xiphoid process of the sternum and, rising, is included in the tendon center of the diaphragm. Near the edge of the sternum, between the sternum and the costal parts of the muscle, there is also a gap (trigonum sternocostal) for the passage of a. et v. thoracicae internae.

Through these weak points of the diaphragm, the internal organs of the abdominal cavity can penetrate into the chest cavity.

The tendon center (centrum tendineum) occupies the dome of the diaphragm and is formed by the tendon of the muscle parts (Fig. 167). To the right of the midline and somewhat posteriorly, at the dome, there is an opening for the passage of the inferior vena cava (for. venae cavae inferioris). Between the edge of the opening of the diaphragm and the wall of the inferior vena cava there are collagen bundles.

The lungs and heart are located on the diaphragm. From the contact of the heart on the diaphragm there is cardiac pressure (impressio cardiaca).

The right dome of the diaphragm is higher than the left, since on the side of the abdominal cavity there is a more massive liver on the right, and a spleen and stomach on the left.

Innervation: n. phrenicus (C III-V).

Function. When the diaphragm contracts, the tendon center lowers by 2-4 cm. Since the parietal layer of the pleura is fused with the diaphragm, when the dome is lowered, it increases pleural cavity, which creates a difference in air pressure between the pleural cavity and the lumen of the alveoli of the lungs. As the diaphragm lowers, the lung expands and the inhalation phase begins. When the diaphragm relaxes under the influence of intra-abdominal pressure, the dome rises again and takes its original position. This corresponds to the exhalation phase.

Embryogenesis of the diaphragm

At the 4th week of embryonic development, at the level of 4-5 cervical somites, mesenchyme folds appear on the dorsal and ventral sides. The ventral fold turns into a transverse fold (septum transversum), which penetrates between the rudiments of the heart and stomach. At the end of the 6th week of intrauterine development, folds protrude from the lateral and posterior walls of the neck, which connect to the septum transversum, forming a connective tissue plate into which the muscle originating from the cervical myotomes grows. By the 12th week of development, the diaphragm, under pressure from the heart and lungs, lowers from the neck and takes a permanent position.

The diaphragm (Fig. 107, 108), which is also called the abdominal barrier, is a muscular partition between the chest cavity and abdominal cavity. This is a thin, wide, unpaired plate, curved with its convex side up, closing the lower opening of the chest.

Rice. 107. Aperture (top view):

1 - lumbar part of the diaphragm;
2 - aortic opening;
4 - esophageal opening;
5 - opening of the vena cava;
6 - tendon center;
7 - sternal part of the diaphragm

The diaphragm functions as the main respiratory muscle. By flattening during contraction, it increases the volume of the chest, facilitating inhalation. When relaxed, the diaphragm takes on a spherical convex shape, reducing the ribcage, which allows exhalation. When contracted together with the abdominal muscles, the diaphragm helps the abdominal muscles work.

All muscle bundles of the diaphragm, which come from the bone and cartilaginous parts of the lower aperture of the chest and lumbar vertebrae, are directed to the center, where they pass into tendon bundles and form the tendon center (centrum tendineum) (Fig. 107, 108), which has the shape of a trefoil. In the tendon center there is a four-sided opening of the vena cava (foramen venae cavae) (Fig. 107, 108), which allows the inferior vena cava to pass through.

Rice. 108. Diaphragm and muscles of the posterior abdominal wall:

1 - sternal part of the diaphragm;
2 - tendon center;
3 - costal part of the diaphragm;
4 - opening of the vena cava;
5 - esophageal opening;
6 - lumbar part of the diaphragm;
7 - medial arcuate ligament;
8 - aortic opening;
9 - median arcuate ligament;
10 - lateral arcuate ligament;
11 - left leg of the diaphragm;
12 - right leg of the diaphragm

At the point where the muscle bundles begin in the diaphragm, three parts are distinguished. The sternal part (pars sternalis diaphragmatis) (Fig. 107, 108) starts from the posterior surface of the xiphoid process. The costal part (pars costalis diaphragmatis) (Fig. 107, 108) is the most extensive. It begins on the inner surface of the bony and cartilaginous parts of the six lower ribs. Its beams are directed upward and inward. The lumbar part (pars lumbalis diaphragmatis) (Fig. 107, 108) is divided into right leg(crus dextrum) (Fig. 108) and left leg(crus sinistrum) (Fig. 108), each of which starts from the anterolateral surface of the I–III lumbar vertebrae and tendon lumbar costal ligaments.

The medial arcuate ligament (lig. arcuatum mediale) (Fig. 108) goes from the body to the transverse process of the 1st lumbar vertebra, the lateral arcuate ligament (lig. arcuatum laterale) (Fig. 108) - from the transverse process of the 1st lumbar vertebra to the XII rib; The median arcuate ligament (lig. arcuatum medianum) (Fig. 108) closes the aortic opening. The central muscle bundles of the lumbar part limit the aortic opening (hiatus aorticus) (Fig. 107, 108), which allows the aorta to pass through. Slightly lower is the esophageal opening (hiatus esophageus) (Fig. 107, 108), which passes through the esophagus.

The thoracic and abdominal surfaces of the diaphragm are covered with fascia.