According to its form rib cage resembles an ovoid with a narrow upper end and a wider lower end, both ends being obliquely cut. In addition, the ovoid of the chest is somewhat compressed from front to back.
Rib cage, compages thoracis, has two openings or apertures: the upper one, apertura throracis superior, and the lower one, apertura thoracis inferior, covered by a muscular septum - the diaphragm. The ribs limiting the lower aperture form the costal arch, arcus costalis. The anterior edge of the lower aperture has an angle-shaped notch, angulus infrastemalis, substernal angle; at its apex lies the xiphoid process. The spinal column juts into the midline chest cavity, and on the sides of it, between it and the ribs, there are wide pulmonary grooves, sulci pulmonales, in which the posterior edges of the lungs are located. The spaces between the ribs are called intercostal spaces, spatia intercostalia.
In mammals, in which, due to their horizontal position, the thoracic viscera exert pressure on the lower wall, the chest is long and narrow, and the ventro-dorsal size exceeds the transverse one, as a result of which the chest has a compressed form from the sides with a protruding ventral wall in the form of a keel (keel-shaped).
In monkeys, due to the division of the limbs into arms and legs and the beginning of the transition to upright walking, the chest becomes wider and shorter, but the ventro-dorsal size still prevails over the transverse (monkey shape).
Finally, in humans, due to the complete transition to upright posture, the hand is freed from the function of movement and becomes a grasping organ of labor, as a result of which the chest experiences the pull of the muscles attached to it upper limb; the insides press not on the ventral wall, which has now become the front, but on the lower one, formed by the diaphragm, as a result of which the line of gravity in a vertical position of the body is transferred closer to the spinal column. All this leads to the fact that the chest becomes flat and wide, so that the transverse dimension exceeds the anteroposterior one. Reflecting this process of phylogenesis, the chest has different shapes in ontogenesis. As the child begins to stand up, walk and use his limbs, and as the entire apparatus of movement and internal organs grow and develop, the chest gradually acquires a characteristic human shape with a predominant transverse dimension.
The shape and size of the chest are also subject to significant individual variations, due to the degree of development of muscles and lungs, which in turn is associated with lifestyle and profession this person. Since it contains such vital important organs, like the heart and lungs, then these variations have great importance for rate physical development individual and diagnosis of internal diseases. Usually there are three shapes of the chest: flat, cylindrical and conical.
In people with well-developed muscles and lungs, the chest becomes wide, but short and takes on a conical shape, that is, its lower part is wider than the upper, the ribs are slightly inclined, the angulus infrasternalis is large. Such a chest is in a state of inhalation, which is why it is called inspiratory. On the contrary, in people with poorly developed muscles and lungs, the chest becomes narrow and long, acquiring a flat shape, in which the chest is strongly flattened in the anteroposterior diameter, so that its anterior wall is almost vertical, the ribs are strongly inclined, and the angulus infrasternalis is sharp. The chest is in a state of exhalation, which is why it is called expiratory.
The cylindrical shape occupies an intermediate position between the two described. In women, the chest is shorter and narrower in the lower section than in men, and more rounded. Social factors on the shape of the chest are reflected in the fact that, for example, in some developing countries, children of the exploited segments of the population living in dark dwellings, due to lack of nutrition and solar radiation, develop rickets (“English disease”), in which the chest takes on the shape “chicken breast”: the anteroposterior size predominates, and the sternum protrudes abnormally forward, like in chickens. IN pre-revolutionary Russia shoemakers who spent their entire lives sitting on a low stool in a bent position and using their chest as a support for the heel when driving nails into the sole, a depression appeared on the front wall of the chest and it became sunken (funnel-shaped chest of shoemakers). In children with long and flat chests, due to poor muscle development, when sitting on a desk incorrectly, the chest appears to be in a collapsed state, which affects the activity of the heart and lungs. To avoid diseases, children need physical education.
Movements of the chest. Respiratory movements consist of alternately raising and lowering the ribs, along with which the sternum moves. During inhalation, the posterior ends of the ribs rotate around the axis mentioned in the description of the joints of the ribs, and their anterior ends are raised so that the chest expands in anteroposterior size. Due to the oblique direction of the axis of rotation, the ribs simultaneously move apart to the sides, as a result of which the transverse size of the chest also increases. When the ribs are raised, the angular bends of the cartilages are straightened, movements occur in the joints between them and the sternum, and then the cartilages themselves are stretched and twisted. At the end of the inhalation caused by the muscular act, the ribs lower, and then exhalation occurs.
The chest is made up of: the bone skeleton, fascia, muscles, vessels and nerves that fill the intercostal spaces. The bony skeleton of the chest consists of the sternum, 12 pairs of ribs and 12 thoracic vertebrae.
The sternum (sternum) is a flat, elongated bone, covered on the outside with a compact substance and consisting inside of a spongy bone substance, rich in blood vessels and containing red bone marrow.
It consists of the manubrium, body and xiphoid process and is closely connected with the strong periosteum covering it.
Ribs(costae), depending on their relationship to the sternum and to each other, are divided into true (I-VII pairs), false (VIII-X pairs) and free (XI-XII pairs). Costae verae, with their cartilages, directly articulate with the sternum, forming articulationes sternocostales. Costae spuriae, sequentially connecting with each other with their cartilages, join the cartilage of the VII rib and form the arcus costalis. Costae fluctuantes end freely in the thickness of soft tissues. To the upper surface of the first rib, to the tuberculum m. scaleni anterioris, the anterior scalene muscle is attached, in front of which edge crosses v. subclavia, and behind in sulcus a. subclaviae passes a. subclavia. The ribs of the chest are tilted forward, and the degree of their tilt increases downward and increases with age. The width of the intercostal spaces varies. The second and third intercostal spaces reach the greatest size, which are therefore most convenient for ligating the internal mammary artery. Other intercostal spaces are narrower. So, the first and fourth intercostal spaces are 1/2 times narrower than the third.
At the back, the chest consists of 12 thoracic vertebrae with their intervertebral discs. They protrude deeply into the chest cavity and divide its posterior section into two sulci pulmonales. From the sides thoracic vertebrae articulate with the ribs at the joints of the head and tubercle of the rib (articulationes capitis costae, articulationes costo-transversariae). The chest has openings at the top and bottom. The upper opening of the chest (apertura thoracis superior) is formed by the body of the first thoracic vertebra, both first ribs and the jugular notch of the manubrium of the sternum. The upper opening, like the ribs, is inclined forward and downward. It, depending on the structure of the first rib, has two extreme shapes and can be narrow when the sagittal diameter of the foramen predominates, or wide when the frontal diameter of the foramen is relatively larger. Important vessels, nerves, trachea, esophagus, as well as the apices of the pleural sacs and lungs are adjacent to the walls of the superior aperture and pass through it. The lower opening of the chest (apertura thoracis inferior) is formed by the body of the XII thoracic vertebra, the XII ribs, the ends of the XI ribs, the costal arches and the xiphoid process. The costal arches form a substernal angle, the value of which can vary from 35 to 120°. With a larger angulus infrasternalis, access to organs top floor abdominal cavity is better than in cases where this angle is small.
Rice. 32. Chest of a newborn.
Outside rib cage covered with a thin sheet of its own fascia, which fuses with the periosteum and perichondrium of the ribs and sternum, with the periosteum of the transverse processes of the vertebrae. Between the fascia and the intercostal muscles there is a thin layer of fiber.
External intercostal muscles (mm. intercostales externi), attached to the edges of the ribs, fill the intercostal spaces from the tubercles of the ribs at the back to the costal cartilages at the front. The muscle fibers are directed obliquely: in the dorsal part of the chest - from top to bottom and laterally, in the lateral part - from top to bottom and forward, in the anterior part - from top to bottom and medially. In the cartilaginous part of the intercostal spaces, the continuation of these muscles in the medial side to the edges of the sternum are membranae intercostales externae, which have the appearance of shiny aponeurotic plates.
Rice. 33. Chest and right shoulder blade. Front view.
Internal intercostal muscles (mm. intercostales interni), attaching to the edges of the ribs with inside, perform intercostal spaces from the lateral edge of the sternum in front to the costal angles in the back. The direction of the muscle fibers is opposite to the previous muscle. The continuation of the muscles in the medial side from the corners of the ribs to the bodies of the thoracic vertebrae are the membra-nae intercostales intemae. Often, muscle bundles are separated from the internal intercostal muscles, which are attached along the inner edge of the sulcus costae and are called mm. intercostales intimate. Between mm. intercostales intimi and intemi there is fiber in which the intercostal space can pass neurovascular bundle or intercostal nerve.
On the back wall of the chest from the chest cavity there are mm. subcostales, which have the same direction as the internal intercostal muscles, but spread over one or even two ribs. Another muscle located on the inner surface of the chest in front is m. transver-sus thoracis. The inside of the chest is lined with fascia endothoracica.
The chest is supplied with blood by the posterior intercostal arteries, originating from thoracic aorta and subclavian arteries, and anterior intercostal and sternal branches from the internal thoracic arteries. Ah. intercostales posteriores of the first two intercostal spaces are branches of aa. intercostales supremae. Starting from subclavian artery or costocervical trunk, a. intercostalis supreme goes back and down, bends around the posterior half of the pleura dome from above, lies anterior to the necks of the 1st and 2nd ribs and gives off here the first, second, and sometimes third posterior intercostal arteries. The right posterior intercostal arteries, arising from the thoracic aorta, bend around the vertebral bodies in front and side and are located behind thoracic duct, azygos vein with intercostal veins flowing into it and behind thoracic borderline sympathetic trunk. At the level of the costal angle, the posterior intercostal artery lies in the sulcus costae. Along the route between the head of the rib and the costal angle, the artery crosses the intercostal space below its rib. Above the artery is the intercostal vein, below is the nerve of the same name. These relationships persist throughout the entire intercostal space. In its initial part, the nerve can also lie above or posterior to the artery. During their course, the posterior intercostal arteries give off numerous branches to the thoracic vertebral bodies, ribs, intercostal muscles, sympathetic trunk, rr. colla-terales and lateral branches supplying the skin and subcutaneous tissue.
A. thoracica interna starts from the subclavian artery, goes forward and down and, between the 1st and 2nd ribs, approaches the inner surface of the anterior chest wall. From here the artery runs down lateral to the sternum, behind the costal cartilages and internal intercostal muscles. At the back, the artery is covered by the intrathoracic fascia, pre-pleural tissue and parietal pleura, and below the cartilage of the third rib it is also covered by the transverse thoracic muscle. From the lateral edge of the sternum, the artery is located on average at a distance of 1-2 cm, but it should be remembered that the artery can lie closer to the sternal edge and even retrosternally. Branches extend from the artery to the organs of the mediastinum (rr. mediastinales, thymici, bronchiales, a. pericardiacophrenica), to the superficial soft tissues(rr. perforan-tes), to the sternum (rr. sternales) and two branches to each intercostal space (intercostales anteriores), of which one runs along the lower, and the other along the upper edge of the rib. The anterior intercostal branches anastomose with the branches of the posterior intercostal artery. Near the diaphragm, the internal mammary artery divides into its terminal branches- a. musculo-phrenica and a. epigastrica superior.
The main veins draining blood from the chest in front are vv. thoracicae internae, receiving blood from the anterior intercostal veins. Blood is taken from the posterior intercostal veins: on the right - v. azygos, left - v. hemiazygos and V. hemiazygos accessoria. The anterior and posterior intercostal veins widely anastomose with each other and are located in the intercostal spaces above the arteries.
Lymph flows from the chest mainly through intercostal lymphatic vessels, which are located either along the upper and lower edges of the ribs, or in the spaces between the ribs, accompanying blood vessels. From the anterior semicircle of the chest, lymph flows into the peristernal The lymph nodes(see lymphatic drainage from the mammary gland). From the posterior semicircle of the chest, lymph flows into small intercostal lymph nodes (from 2 to 5), located in the intercostal spaces between the neck and head of the rib. Lymphatic vessels from these nodes behind the azygos and semi-gyzygos veins and the aorta they go to the thoracic proton, forming a large-leaf plexus, which includes lymph nodes. From the second or third upper intercostal spaces, lymph flows into the lower deep ones. cervical nodes, located at the brachial plexus.
Rice. 34. Posterior (inner) surface of the anterior wall of the chest cavity.
On the right, the intrathoracic fascia has been removed.
Rice. 35. Muscles, fascia, vessels and nerves of the anterior chest wall. Front view.
On the right, in the upper three intercostal spaces, the fascia is preserved; below, the fascia and external intercostal membrane are removed and the intercostal muscles are exposed. On the left, the IV and V ribs with intercostal muscles were partially removed and the internal ones were prepared thoracic vessels parasternal lymph nodes and intercostal vessels and nerves.
Rice. 36. Vessels and nerves of the posterior chest and posterior mediastinum. Front view, from the chest cavity.
Rice. 37. Vessels and nerves adjacent to the right dome of the pleura. Bottom view, from the side
pleural cavity (2/3).
Innervation. Each of the thoracic spinal nerves (n. thoracicus), emerging from the intervertebral foramen, gives off: g. meningeus, g. communicantes to the sympathetic trunk and two large branches - g. dorsalis and g. ventralis, or n. intercostalis. The exception is the I thoracic nerve, the main part of the ventral branch of which (and sometimes the II thoracic) goes to the formation brachial plexus. Due to this, the first intercostal nerve is much thinner than the others. Typically, each intercostal nerve is directed laterally and, having reached the costal angle, penetrates between the external and internal intercostal muscles, located below the intercostal vessels. From the intervertebral foramen to the costal angle, the nerve may be located above, below, or behind the intercostal artery. In this area, the nerve in front is covered with thin intrathoracic fascia, subpleural tissue and pleura. The presence of such a thin wall separating the nerve from the pleural cavity causes involvement of the nerve in pleurisy. inflammatory process. Moving laterally and forward from the costal angle, the intercostal nerve is located below the lower edge of its rib and can even approach the upper edge of the underlying rib. Only in the first to third intercostal spaces can the nerve be directly adjacent to the lower edge of the rib or rise higher, hiding behind the rib. Throughout part or all of the intercostal space, the nerve can pass between mm. intercostales inkrnus and intimus. In these cases, the nerve is separated from the parietal pleura by only a very thin m. intercostalis intimus and intrathoracic fascia, and from the vessels - the internal intercostal muscle. Along the entire length of the intercostal nerve, branches depart from it, innervating the intercostal and subcostal muscles, the transverse thoracic muscle, the parietal pleura, as well as the skin of the lateral and anterior surface of the chest. The lateral cutaneous branches (rr. cutanei laterales pectorales) pierce the intercostal muscles and approximately from the mid-axillary line (and in the lower part somewhat posterior to it) exit into the subcutaneous tissue, where they again divide into the anterior and posterior branch, innervating the skin of the lateral and anterolateral surface of the chest. The intercostal nerves (from II to V-VI inclusive), reaching the lateral surface of the sternum, give off rr. cutanei anteriores pectorales, which penetrate the subcutaneous tissue, where they are divided into medial and lateral branches. Starting from VI-VII, intercostal nerves penetrate into the anterior abdominal wall, where they innervate the skin, muscles and parietal peritoneum.
Rice. 38. Vessels and nerves adjacent to the left dome of the pleura. Bottom view, from the side
left pleural cavity.
Between the posterior axillary and parasternal lines VI-XI, intercostal nerves in 25% of cases are located on the inner surface of mm. intercostales interni and on the side of the thoracic cavity are covered only by fascia and parietal pleura. Directly under the pleura and fascia lie the intercostal nerves in the posterior sections of the intercostal spaces (Fig. 36). Irritation of the six lower intercostal nerves in pleurisy and pneumonia can simulate acute illness abdominal cavity (abdominal pain, muscle dysfunction, etc.) and cause diagnostic errors.
Rice. 39. Arteries of the chest and anterolateral abdominal wall and their connections
(radiographs).
1, 13 - a. musculophrenlca; 2, 10 - gg. intercostales anteriores; 3" 5, 14 - a. thoracica interna; 4 - g. costalis lateralis; 6 - a. intercostalls surpema; 6 - a. spinalis; 7 - rr. dorsales; 8 - arcus aortae; 11 - aorta thoracica; 12 - aa. intercostales posteriores; 15 - a. epigastrca superior; 16-a. circumflexa ilium profunda; 17 - a. eplgastrica Inferior; 18 - a. eplgastrica superficialis; 19 - branches aa. lumbales.
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The chest is part of the torso. It is formed by the sternum, ribs, spine and, of course, muscles. It contains the thoracic part and the upper part of the peritoneum. The respiratory muscles, which are fixed on the outside and inside, create the conditions for human breathing.
Structure
There are four sections in the chest frame - anterior, posterior and two lateral. It has two holes (apertures) - upper and lower. The first is limited behind at the level of the very first thoracic vertebrae, on the side by the uppermost ribs, and in front by the manubrium of the sternum. The top of the lung enters the aperture and the esophagus and trachea pass through it. The lower opening is wider, its boundaries run along the twelfth vertebra, along the ribs and arches, through the xiphoid process and are closed by the diaphragm.
The chest frame consists of twelve pairs of ribs. In front is the cartilaginous apparatus and the sternum. At the back are twelve vertebrae with ribs and the spinal column.
The main role of the cell is to protect vital organs, namely the heart, lungs and liver. When the spine is deformed, transformations are observed in the chest itself, which is extremely dangerous and can lead to compression of the organs located in it, which leads to disruption of their functioning, and, subsequently, to the development of various diseases.
Ribs
Each rib includes bone and cartilage; their special structure prevents damage to organs during impacts.
The seven large upper ribs are connected to the sternum. Below there are three more ribs attached to the upper cartilages. The rib cage ends with two floating ribs, which are not combined with the sternum, but are attached exclusively to the spine. All together they create a single frame that serves as a support. It is almost motionless, since it consists entirely of bone tissue. Instead of this tissue, a newborn has cartilaginous tissue. Actually, these ribs form the posture.
- sit and stand straight;
- engage actively in sports that strengthen the back muscles;
- Use the right mattress and pillow.
The main task of the ribs is not to interfere with respiratory movement and protect the organs that are located inside the cell from injury.
Sternum
The sternum looks like a flat bone and includes three sections - the upper (manubrium), middle (body) and lower (xiphoid process). In structure, it is spongy bone, covered with a denser layer. On the handle you can see the jugular notch and a pair of clavicular notches. They are needed for attachment to the upper pair of ribs and collarbone. The largest section of the sternum is the body. 2-5 pairs of ribs are attached to it, and the formation of sterno-costal joints occurs. Below there is a xiphoid process that is easy to palpate. It can be different: blunt, pointed, split and even have a hole. It completely ossifies by the age of 20.
Form
In young children, the chest is convex in shape, but over the years, with correct growth, it changes.
The cell itself is normally flattened, and its shape depends on gender, the constitution of the body and the degree of its physical development.
There are three chest shapes:
- flat;
- cylindrical;
- conical
A conical shape occurs in a person with high level muscle and lung development. The chest is large but short. If the muscles are poorly developed, then the cell narrows and lengthens, taking on a flatter shape. Cylindrical is the middle shape between the above.
Under the influence of external and internal factors the form may change pathologically.
Pathological forms of the chest:
- Emphysematous, it occurs in people suffering from chronic pulmonary emphysema
- Paralytic. Changes occur in patients with reduced lung mass; this occurs with prolonged diseases of the lungs and pleura.
- The rickets form occurs in people who suffered from rickets in childhood.
- The funnel-shaped form is distinguished by a funnel-shaped fossa in the area of the xiphoid process and the lower part of the sternum.
- The scaphoid shape occurs in diseases of the spinal cord.
- The kyphoscoliotic form occurs when there is curvature of the spine as a result of arthritis or tuberculosis.
Movement
Movement occurs when a person breathes.
When inhaling, the almost motionless frame increases along with the intercostal spaces, and when exhaling it decreases, while the spaces narrow. This occurs due to special muscles and mobility of the costal cartilages.
During quiet breathing, the respiratory muscles are responsible for cell movement, the most important of which are the intercostal muscles. When they contract, the chest expands to the sides and forward.
If you need to catch your breath after physical activity, then auxiliary respiratory muscles join them. In case of illness or when oxygen access to the lungs is difficult, the muscles attached to the ribs and other parts of the skeleton begin to work. By contracting, they increase the stretch of the chest.
Features and age-related changes
At birth, all children have a cone-shaped chest. Its transverse diameter is small and the ribs are located horizontally. The costal heads themselves and their endings lie in the same plane. Later upper limit The sternum decreases and is located in the area of the 3rd and 4th vertebrae. The determining factor is the appearance chest breathing in children. The first two years are characterized rapid growth cells, but by the age of seven, growth becomes slower, but the middle section of the cell increases the most. By about the age of twenty, the breasts acquire their usual shape.
Men have a larger chest than women. It is also characterized by a stronger curvature of the ribs, but their spiral twisting is less typical. This specificity influences both cell shape and respiration patterns. In a woman, due to the strong spiral shape of the ribs, the front end is lower and the shape is more flattened. For this reason, her chest type of breathing dominates. This differs from men, in whom the respiratory process occurs due to the movement of the diaphragm and is called the abdominal type.
It has been proven that people with different body compositions also have a characteristic chest shape. A person does not tall with extended abdominal cavity the chest will be wider, but shorter, with an expanded lower opening. Conversely, a tall person will have a longer and flatter chest shape.
Around the age of 30, a person begins to ossify. As we age, cartilage loses its mobility, leading to a greater likelihood of injury. The diameter of the breast also decreases, this leads to disturbances in the functioning of the organs themselves and the system as a whole, and the shape of the cell changes accordingly.
To prolong the health of your body, and in particular the chest, you need to perform physical exercises. To strengthen muscles, it is recommended to exercise with a barbell or dumbbells, and perform a set of special exercises on the horizontal bar. Always, from childhood, it is necessary to monitor your posture. As recommended by doctors, take vitamins and calcium. This is especially necessary for pregnant women and the elderly. At the onset of diseases, chondroprotectors are prescribed that can stop the destruction of bone tissue.
Need to stick healthy eating. The diet should contain vegetables, fruits, meat and seafood in sufficient quantities. It is also useful to use dairy products, which are high in calcium and vitamin D.
The chest (compages thoracis) consists of ribs connected at the anterior ends to the sternum (sternum), and at the posterior ends to the thoracic vertebrae. The frontal surface of the chest, represented by the sternum and the anterior ends of the ribs, is much shorter than its posterior or lateral surfaces. The chest cavity, bounded below by the diaphragm, contains vital organs - the heart, lungs, large vessels and nerves. Also inside the chest (in the upper third, just behind the sternum) is the thymus gland.
The spaces between the ribs that make up the chest are occupied by the intercostal muscles. The bundles of external and internal intercostal muscles pass in different directions: the external intercostal muscles - from the lower edge of the rib obliquely down and forward, and the internal intercostal muscles - from the upper edge of the rib obliquely upward and forward. Between the muscles there is a thin layer of loose fiber in which intercostal nerves and vessels pass.
Newborns have a chest that is noticeably compressed from the sides and extended forward. With age, sexual dimorphism is clearly manifested in the shape of the chest: in men it approaches cone-shaped, expanding from below; in women, the chest is not only smaller in size, but also different in shape (expanding in the middle part, narrowing in both the upper and lower parts).
Sternum and ribs
The sternum (sternum) (Fig. 14) is a long, spongy, flat-shaped bone that closes the chest in front. The structure of the sternum is divided into three parts: the body of the sternum (corpus sterni), the manubrium of the sternum (manubrium sterni) and the xiphoid process (processus xiphoideus), which fuse with age (usually by 30–35 years) into a single bone (Fig. 14). At the junction of the body of the sternum with the manubrium of the sternum there is a forward-directed angle of the sternum (angulus sterni).
The manubrium of the sternum has two paired notches on its lateral surfaces and one paired notch on the upper part. The notches on the lateral surfaces serve to articulate with the two upper pairs of ribs, and the paired notches in the upper part of the manubrium, called clavicularis (Fig. 14), serve to connect to the bones of the clavicles. The unpaired notch located between the clavicular notches is called the jugular (incisura jugularis) (Fig. 14). The body of the sternum also has paired costal notches (incisurae costales) on its sides (Fig. 14), to which the cartilaginous parts of the II–VII pairs of ribs are attached. The lower part of the sternum - the xiphoid process - can vary significantly in size and shape from person to person, and often has a hole in the center (the most common shape of the xiphoid process is close to a triangle; xiphoid processes that are forked at the end are also often found).
Rice. 14. Sternum (front view):
1 - jugular notch; 2 - clavicular notch; 3 - manubrium of the sternum; 4 - rib notches; 5 - body of the sternum; 6 - xiphoid process
Rice. 15. Ribs (top view) A - 1st rib; B - II rib:1 - tubercle of the rib;2 - rib angle;3 - rib neck;4 - rib head;5 - rib body
The rib (costae) (Fig. 15) is a long, spongy, flat-shaped bone that bends in two planes. In addition to the bone itself (os costale), each rib also has a cartilaginous part. The bone part, in turn, includes three clearly distinguishable sections: the body of the rib (corpus costae) (Fig. 15), the head of the rib (Fig. 15) with the articular surface on it (facies articularis capitis costae) and the neck of the rib separating them (collum costae) (Fig. 15).
The body's ribs are distinguished by outer and inner surfaces and upper and lower edges (except for I, in which the upper and lower surfaces and outer and inner edges are distinguished). At the junction of the neck of the rib with the body there is a tubercle of the rib (tuberculum costae) (Fig. 15). At the I–X ribs, behind the tubercle, the body bends, forming a rib angle (angulus costae) (Fig. 15), and the tubercle of the rib itself has an articular surface through which the rib articulates with the transverse process of the corresponding thoracic vertebra.
The body of the rib, represented by spongy bone, has a different length: from the first pair of ribs to the VII (less often VIII) the length of the body gradually increases; at the next ribs the body is successively shortened. Along the lower edge of its inner surface the body of the rib has a longitudinal groove of the rib (sulcus costae); intercostal nerves and vessels pass through this groove. The anterior end of the first rib also has on its upper surface a tubercle of the anterior scalene muscle (tuberculum m. scaleni anterioris), in front of which there is a groove of the subclavian vein (sulcus v. subclaviae), and behind it there is a groove of the subclavian artery (sulcus a. subclaviae).
chest, compares thoracis, make up the thoracic spinal column, ribs (12 pairs) and sternum.
The chest forms the chest cavity, cavitas thoracis, which has the shape of a truncated cone, with its wide base facing downward and its truncated apex facing upward. The chest is divided into anterior, posterior and side walls, the upper and lower openings that limit the chest cavity.
The structure of the chest.
The anterior wall is shorter than the other walls, formed by the sternum and cartilage. Positioned obliquely, it protrudes more anteriorly with its lower sections than with its upper ones. The posterior wall is longer than the anterior one, formed by the thoracic vertebrae and
sections of ribs from the heads to the corners; its direction is almost vertical.
On outer surface back wall of the chest, between the spinous processes of the vertebrae and the corners of the ribs, two grooves are formed on both sides - dorsal grooves: deep grooves lie in them. On the inner surface of the chest, between the protruding vertebral bodies and the corners of the ribs, two grooves are also formed - pulmonary grooves, sulci pulmonales; they are adjacent to the vertebral part of the costal surface of the lungs.
The lateral walls are longer than the front and back, formed by the bodies of the ribs and are more or less convex.
The spaces bounded above and below by two adjacent ribs, in front by the lateral edge of the sternum and behind by the vertebrae, are called intercostal spaces, spatia intercostalia; they are made by intercostal muscles and membranes.
The chest, compages thoracis, bounded by the indicated walls, has two openings - upper and lower, which begin as apertures.
The upper aperture of the chest, apertura thoracis superior, is smaller than the lower one, limited in front by the upper edge of the manubrium, on the sides by the first ribs and behind by the body I. It has a transverse oval shape and is located in a plane inclined from back to front and downwards. The upper edge is located at the level of the gap between the II and III thoracic vertebrae.
The lower aperture of the chest, apertura thoracis inferior, is limited in front by the xiphoid process and the costal arch formed by the cartilaginous ends of the false ribs, on the sides by the free ends of the XI and XII ribs and the lower edges of the XII ribs, and behind by the body of the XII.
The costal arch, arcus costalis, at the xiphoid process forms an open substernal angle, angulus infrasternalis.
