Chest

Synonyms in a broader sense

  • Chest
  • Chest
  • Chest area
  • Breastbone
  • Sternum
  • Ribs
  • Thoracic Spine
  • Diaphragm
  • Lung

Anatomically limiting for the chest (thorax) upwards and downwards on a standing person (craniocaudal direction) are two openings of the thorax, an upper thoracic aperture (Apertura thoracis superior) and a lower thoracic aperture (Apertura thoracis inferior). The upper thoracic aperture provides the transition from a centrally located connective tissue space of the chest (mediastinum) to the connective tissue spaces of the neck. Consequently, in addition to numerous blood vessels, nerves and lymphatic pathways, the trachea and esophagus in particular pass from the neck into the thorax.

The upper thoracic aperture is surrounded at the front by the first two ribs (costae, singular costa) and a retraction of the sternum (incisura jugulars sterni), at the back by the first thoracic vertebra (see spine, thoracic spine). The lower thoracic aperture marks the transition from the chest to the abdominal cavity and is separated from it by the diaphragm (diaphragm), which extends within the aperture (lat. opening) and undergoes considerable positional changes during breathing (respiration).

The lower opening is bordered at the front by a sword-shaped extension of the sternum (Processus xiphoideus), the costal arch (Arcus costalis) on each side of the body and the ends of the last two ribs (11th and 12th ribs usually end freely in the abdominal muscles and have no contact with the costal arch), and at the back by the last, the 12th thoracic vertebra. The border between the abdomen and chest, which can be assumed from the outside, does not correspond to the actual anatomical border. For example, the space under the right costal arch (Arcus costalis dexter) is almost completely filled by the liver, which belongs to the right upper abdomen.

Similar to the transition from the neck to the chest, a large number of prominent pathways (blood vessels, lymphatic pathways, nerves) and the esophagus pass through the lower aperture and penetrate the diaphragm in certain sections. The anterior and posterior limits (dorsoventral direction) of the thorax in an upright person are the bony-cartilaginous elements of the ribs, the sternum and the back of the spine, which here describes an arc to the back (thoracic kyphosis). These are supplemented by an elaborate system of connective tissue (bony-cartilaginous elements + ligamentous apparatus = “ligamentous thorax”, the passive locomotor system of the breast) to form a wall for the thoracic cavity (Cavitas thoracis) located inside this thorax, in which the breast tissue is also located.

The joints of the thorax are also briefly mentioned here. The thoracic spine is actually hardly bendable, only the rotation is noteworthy. Our 12 pairs of ribs (each half of the body usually has 12 ribs, hence “pairs of ribs”.

Counted from top to bottom) are connected to the thoracic spine in their posterior origin by two “true” joints (diarthroses), whereby firstly the head of the rib (caput costae) is connected to the vertebral bodies (corpus vertebrae) by a recess and secondly the tubercle (tuberculum costae) is connected to the transverse processes of the vertebrae by joints. These are largely uniaxial swivel joints whose axis runs through the neck of the ribs (Collum costae), only ribs 6-9 form sliding joints at their cusps with the transverse processes of the vertebrae (vertebrae), so that the cusp does not rotate but slides slightly up and down. Except for the two lowest ribs, each has some kind of contact with the sternum, so that the ribs form a closed ring system, which gives the continuity of the thorax, e.g. the 3rd rib of the left half of the body together with the sternum and the 3rd rib of the right half of the body form a continuous arc.

At the sternum, the ribs are rather held by “fake” joints (synarthroses), which are more or less tight and hardly allow any movement. The decisive factor in the movement of the ribs on the sternum is therefore the twisting of the cartilaginous part of the ribs in conjunction with the rotation they undergo at the back of the spine. In sum, this results in a swinging of the ribs upwards during inhalation (inspiration), which widens the chest space, and in opposite movements during exhalation (expiration).The ball-joint connection of the collarbone with the sternum plays a more important role in the movements of the shoulder girdle and arms.

Between the ribs of one half of the body there is a free space, intercostal space (spatium intercostale). This is strongly tensed with muscles, especially the intercostal muscles (Musculi intercostales) and ligaments, which, in addition to the continuity of the rib ring system in the horizontal (transverse) direction, causes tension from bottom to top (dorsocranial direction). At the bottom and slightly inclined towards the inside of the chest, a groove (sulcus costae) is hidden on each rib, which is limited by intercostal muscles.

In this groove run the arteries, veins and nerves (arteria, venae et nervi intercostales) that systematically supply the chest wall.

  • Liver
  • Diaphragm
  • Heart
  • Lung
  • Windpipe
  • Thyroid gland
  • Collarbone
  • Rib
  • Chest wall
  • Pleura (pleura)
  • Stomach
  • Colon

The view of the human skeleton from the front (ventral) reveals the bony-cartilaginous components of the thorax: sternum, ribs (costae,singular costa) and the thoracic spine. The transition from the rib bone to the rib cartilage and the thoracic apertures are clearly visible here.

In order to gently open this entire construct for a heart operation, for example, a great deal of effort and sensitivity is required from the physicians. Thoracic surgery is a demanding specialty. The walls of the chest protectively enclose the breast tissue: the heart (Cor), one lung (Pulmo) in each half of the body and the thymus (sweetbread).

In addition, there are highly important blood and lymphatic vessels and nerve tracts. The thorax, heart and lungs need to be able to change their size considerably in order to perform their function; the thorax and lungs need the heart to fill up with blood or to expel it because of breathing (respiration). The construct that makes this mechanism possible is indispensable for understanding our chest and, by the way, our abdomen!

it is called “serosa” or “serous membranes”, always consists of two layers of cells (leaves), is named differently on each of the organs involved: and follows an essentially trivial principle: imagine an inflated balloon that is firmly knotted at its opening. Into this balloon you arch your clenched fist at any point until it comes to rest in the center of the balloon. One layer of the balloon wall lies directly against your fist, the other is on the outside, as in the original state.

Now push your fist further forward until the two rubber layers of the balloon touch. That’s it! In terms of organ systems with serous membranes, heart, lungs, abdomen, the fist corresponds to the organ, your arm to the suspension of the organ, the balloon layer directly adjacent to the fist to the cell layer close to the organ (visceral leaf) and the outer cell layer to the cell layer on the wall (parietal leaf).

All the above-mentioned conditions are now applied to the thorax (chest): In analogy to the fist and the balloon, the lungs are fused with the cell layer close to the organ (pleura, visceral pleura) and are only separated by a small gap (pleural gap) from the cell layer close to the wall (pleura, parietal pleura), which in turn is fused with the rest of the thoracic wall (muscles, connective tissue, ribs, breastbone, spine). One could only speak of a thoracic cavity in the sense of the word “cavity” if the lungs and the organs of the mediastinum were removed; in living humans (in situ), the intestines fill the chest almost completely. The wall-placed pleura (pleura parietalis) is thus like a wallpaper for the space inside our breast, it lines it, and the inner pleura (pleura visceralis) envelops the lungs (the fist from our thoughts) and approaches the wall-placed outer “wallpaper” from inside.

In addition, it must also be said that two depressions like room dividers in the depth of the breast emanate from the “wallpaper” (the pleura parietalis), which divide the space and border the central connective tissue space (mediastinum) of the breast from the side.The two skins of the pleura merely adhere to each other, because there is a slight vacuum in the mentioned gap (pleural gap) and it is filled with a few milliliters of “serous liquid”, so that “adhesive forces” (“sticking forces”) arise, comparable to two wet glass panes lying on top of each other. If the two skins lose their contact with each other, for example when a knife is stabbed in the thorax, the affected lung collapses due to its tendency to spontaneously contract (lung retraction force), while the thorax expands as usual during breathing. In this case, the lung cannot follow the breathing excursions of the thorax, and without an intact pleura no productive (sufficient) breathing is possible.

As mentioned above, the thorax expands visibly to everyone by the activity of the respiratory and auxiliary breathing muscles during inspiration, just as the abdomen protrudes. It is only through this increase in volume during inspiration that the inner space of the lungs is enlarged to such an extent that air can flow into the lungs from outside. As a result, the pressure inside the chest increases while the volume decreases, air flows out of the lungs via the trachea.

In other words, it is only because the lungs are connected to the wall of our chest through the two layers of the pleura that we can breathe. Now we have already learned about the considerable demands that our species makes on its chest. On the one hand, it must have sufficient stability to protect the viscera, and on the other hand, it must have the mobility (viscoelasticity) to ensure the respiratory function.

As we already know, the thoracic thorax as a whole includes a connective tissue area located in the middle of the chest, the mediastinum. Towards the head it merges into the connective tissue of the neck, and ends at the diaphragm. Its lateral boundaries are formed by the wall-shaped outer ribcage.

Within the mediastinum, the structures outdo each other in importance, the most decisive ones being mentioned: The heart (cor) together with the pericardium (pericardium) as well as the thymus (sweetbreads), the aorta, the superior vena cava, the pulmonary arteries and veins (arteriae et venae pulmonales), the left and right phrenic nerve (a.o. nerve supply (innervation) diaphragm)) as well as the various divisions of vegetative nerves such as the vagus nerve or the boundary strand, the most powerful lymphatic vessel (lactiferous duct, thoracic duct), esophagus and trachea, or left and right main bronchus (bronchus principalis sinister et dexter).

  • Lungs: pleura, pleural
  • Heart: pericardium, pericardium
  • Belly: Peritoneum, Peritoneum
  • Collarbone
  • Rib
  • Lung
  • Chest wall
  • Heart
  • Diaphragm
  • Liver
  • Mediastinum
  • Dermal artery (aorta)
  • Superior vena cava (vena cava)

Read next article in this series:

All articles in this series:

  1. Chest
  2. Anatomy and Function
  3. How is the thorax diagnosed?
  4. Thoracic Drainage