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 inclined forward, and the degree of their inclination 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 the organs of the upper floor of the 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 side - 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.
The internal intercostal muscles (mm. intercostales interni), attached to the edges of the ribs on the inside, fill the 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 neurovascular bundle or intercostal nerve can pass.
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 by the posterior intercostal arteries, originating from the thoracic aorta and subclavian arteries, and the 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 the 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 the thoracic duct, the azygos vein with the intercostal veins flowing into it, and behind the thoracic portion of the 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 (rr . 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 the intercostal lymphatic vessels, which are located either along the upper and lower edges of the ribs, or in the spaces between the ribs, accompanying the blood vessels. From the anterior semicircle of the chest, lymph flows into the parasternal lymph nodes (see lymph 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 are directed 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 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 4th and 5th ribs with intercostal muscles were partially removed and the internal thoracic vessels, parathoracic lymph nodes and intercostal vessels and nerves were prepared.
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 form the 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 the involvement of the nerve in the inflammatory process in pleurisy. 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) enter the subcutaneous tissue, where they again divide into anterior and posterior branches that innervate the skin of the lateral and anterolateral surfaces 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, the intercostal nerves penetrate 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 during pleurisy and pneumonia can simulate an acute disease of the 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 (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 laterally 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 ones 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).
The chest is part of the external respiratory apparatus. It performs a supporting, motor, and protective function.
Rib cage. Structure
This area is represented by a structure that has an osteochondral skeleton. Lymphatic and blood vessels, corresponding skeletal muscles, and other soft fibers pass here.
The osteochondral skeleton consists of twelve thoracic vertebrae, twelve pairs of ribs and the sternum. They are connected to each other through various types of connections.
The cavity of the structure contains internal organs: lungs, lower respiratory tract, esophagus, heart and others.
The chest is presented in the shape of an irregular cone, the top of which is cut off. It defines four walls. The anterior one is formed by the costal cartilages and sternum, the posterior one by the posterior edges of the ribs and the thoracic vertebrae. The lateral (lateral) walls are formed by ribs, which are separated by intercostal spaces (intercostal spaces).
The thorax has an upper aperture (opening), limited by the first upper end with the jugular notch located on it and the inner ends of the first ribs. The hole is inclined anteriorly. The leading edge of the aperture is lowered downwards in the direction of the ribs. Thus, the jugular notch in the sternum is located between the second and third thoracic vertebrae at the level of the intervertebral disc.
The esophagus and trachea pass through the upper opening.
The inferior foramen is bounded by the body of the twelfth thoracic vertebra posteriorly, the sternal xiphoid process anteriorly, and the lower ribs on the sides. Its size is significantly larger than the size of the upper aperture.
The junction of the seventh to tenth costal pairs forms the anterolateral margin (costal arch). The left and right costal arches laterally limit the substernal angle, which is open downward. At its apex, located at the level of the ninth thoracic vertebra, there is
The diaphragm, which has an opening for the passage of the esophagus, aorta, and inferior vein, closes the lower aperture.
Pulmonary grooves are located on the sides of the thoracic vertebrae. In them, the posterior portions of the lungs are adjacent to the walls of the chest.
Flexible rib arches give elasticity and greater strength to the entire structure.
The chest can have different shapes and sizes.
The movement of the entire structure is determined by the processes of exhalation and inhalation (breathing movements). Due to the fact that the anterior ends of the ribs are connected to the sternum, inhalation is accompanied by movement of both the sternum and ribs. Their elevation leads to an increase in the anteroposterior (sagittal) and transverse dimensions of the cell, and expansion of the intercostal spaces (intercostal spaces). All these factors explain the increase in cavity volume.
Exhalation is accompanied by drooping of the sternum and ends of the ribs, a significant decrease in the anteroposterior size, and narrowing of the intercostal spaces. All this leads to a decrease in cavity volume.
Chest deformity
This phenomenon often occurs in children. The two most common are funnel breast and chicken breast.
In the first case, the condition is caused by an abnormal inward retraction of the sternum. Chicken breast is when the chest sticks out. It should be noted that this type of deformation is detected quite rarely in practice.
Structural anomalies certainly affect the child’s health. With a protruding chest, emphysema (a chronic lung disease manifested by breathing problems) often develops.
As practice shows, in most cases this type of deformity requires surgical intervention.
When providing medical care, it is very important to have knowledge of how the human body functions, what organs and systems it consists of, and what changes occur in it with age. This will significantly simplify the diagnosis of diseases and the treatment process, especially by surgical methods.
In order to effectively treat diseases of the respiratory system, heart and others, you need to know what the human chest is. Knowledge about this is necessary not only for doctors, but also for patients themselves, since this will allow them to better understand what is happening in their body.
The chest skeleton is quite complex, containing different types of bones. The bones of the chest are connected by joints and ligaments, and within this bone frame are organs. This frame protects internal organs from injury and damage.
Structure of the chest
The human skeleton can be divided into sections. One of them is the skeleton of the torso, which includes the rib cage. The peculiarity of the human chest is that it is wider from right to left than from front to back. This is explained by the fact that people most often remain in an upright position. But this is not the only reason. This structure of this area is associated with the influence of the chest muscles on it.
The frame of this section can be divided into four parts: front, rear and side. There are holes at the bottom and top of the frame.
The chest contains bones, cartilage, ligaments and joints. Each element is characterized by individual features and functions. Among the main ones are the following bones:
- sternum,
- costal cartilage,
- vertebrae,
- ribs
Structure of the chest
The main element, without which the chest would not be able to perform its functions, are the ribs. There are 12 pairs in total. The upper 7 of them are stable because they are attached to the sternum. These ribs do not move or shift (unless a person has injured them). The next 3 pairs of ribs are also not movable, although they are attached not to the sternum, but to the upper ribs with the help of cartilage.
The costal skeleton is completed by two floating ribs that are not connected to the rest of the ribs and the sternum. Their back part is attached to the thoracic spine, which allows these ribs to move.
This area consists mainly of bones, so it is inherently immobile. The skeleton of this area in infants is represented by cartilaginous tissue, but as the child grows up, it hardens and acquires the same features that are characteristic of adults.
Since the main role of this department is to protect the internal organs, it is worth knowing which organs are located in the chest. There are quite a lot of such organs that are supposed to be inside the bone frame.
This:
- lungs;
- heart;
- bronchi;
- trachea;
- liver;
- thymus gland;
- esophagus, etc.
In addition to the listed organs, there should be separate sections of the lymphatic system.
It is these organs of the chest that need to be protected from harmful external influences.
Since the ribs and other bones that make up the frame of this area can be damaged due to careless behavior, you need to treat your body with great care and attention. Any adverse symptoms, including pain that occur too often, are a reason to consult a doctor.
Functions and age characteristics
The main function that this structure should perform is to protect internal organs from damage and exposure to the external environment. The internal organs of the human body are sensitive, so any excessive impact can harm them.
Thanks to a strong frame of bones, negative influences can be avoided, but this does not mean that the bone structure can protect against any problems. If the impact is too strong, there is a risk of chest deformation, which is very dangerous.
When deformed, pressure is exerted on the organs located inside, which interferes with their functioning and increases the risk of pathological transformations.
There are other functions of the chest:
Chest changes
This area undergoes a considerable number of changes caused by age. Much of these changes occur as we grow older. In infancy, most of the structures of the chest are represented by cartilage tissue. Only as the child grows, more and more areas acquire a bone structure.
Another part of the changes that occurs in a growing person is an increase in the size of all elements. This is caused by the growth of the entire body and internal organs hidden within this framework. Their growth contributes to the growth of the chest. Another difference characteristic of childhood is that the frontal size of the child’s GC is smaller than the sagittal one.
With the transition of a person to the period of aging, changes also arise in this area. The main one is the loss of elasticity of the costal cartilages. This weakens the mobility of the ribs. This also affects the breathing process, since the amplitude of movements of the chest cavity decreases. The elasticity of cartilage tissue in the vertebrae is also lost, which affects the mobility of the back and the flexibility of the lower back.
People need to know the age-related features of the chest, even if they are not doctors by profession.
This will allow them not to experience excessive anxiety when adverse events are detected, but will not allow them to ignore signs of disease development.
Some development features
Despite the fact that the principle by which this department is formed is common to everyone, differences may still be found among different people. Some of them are caused by age, since as you grow up and age, the bone structure of this area and the features of its functioning change.
However, in addition to age, differences may be caused by belonging to different genders. Men tend to have larger frame sizes than women. They also have more curved ribs. Female representatives have a thinner and flatter frame.
The features of this structure are also influenced by differences in physique. In people of short stature, the chest seems to be shortened. Those who are tall are characterized by elongation of this section. Various formations that have arisen in the sternum during life can also affect the shape.
The characteristics of this part of the body can be affected by previous diseases, unfavorable living conditions and other characteristics. It is important to take care of your body, then much fewer deviations from the norm will be found in it. In order for actions in this direction to be correct, it is very important to obtain the necessary information about the functioning of the human body.
Sternum(sternum) is an unpaired long flat spongy bone *, consisting of 3 parts: the manubrium, the body and the xiphoid process.
* (Spongy bone is rich in the circulatory system and contains red bone marrow in people of any age. Therefore, it is possible: intrathoracic blood transfusion, taking red bone marrow for research, red bone marrow transplantation.)
Sternum and ribs. A - sternum (sternum): 1 - manubrium sterni; 2 - body of the sternum (corpus sterni); 3 - xiphoid process (processus xiphoideus); 4 - costal notches (incisurae costales); 5 - angle of the sternum (angulus sterni); 6 - jugular notch (incisure jugularis); 7 - clavicular notch (incisure clavicularis). B - VIII rib (inside view): 1 - articular surface of the rib head (facies articularis capitis costae); 2 - neck of the rib (collum costae); 3 - rib angle (angulus costae); 4 - body of the rib (corpus costae); 5 - rib groove (sulcus costae). B - I rib (top view): 1 - rib neck (collum costae); 2 - tubercle of the rib (tuberculum costae); 3 - groove of the subclavian artery (sulcus a. subclaviae); 4 - groove of the subclavian vein (sulcus v. subclaviae); 5 - tubercle of the anterior scalene muscle (tuberculum m. scaleni anterioris)
Lever makes up the upper part of the sternum, on its upper edge there are 3 notches: unpaired jugular and paired clavicular, which serve for articulation with the sternal ends of the clavicles. On the side surface of the handle two more notches are visible - for the 1st and 2nd ribs. The manubrium, connecting to the body, forms an anteriorly directed angle of the sternum. At this point the second rib is attached to the sternum.
Body of the sternum long, flat, widening at the bottom. On the lateral edges it has notches for attaching the cartilaginous parts of the II-VII pairs of ribs.
xiphoid process- This is the most variable part of the sternum in shape. As a rule, it has the shape of a triangle, but can be bifurcated downwards or have a hole in the center. By age 30 (sometimes later), parts of the sternum fuse into one bone.
Ribs(costae) are paired bones of the chest. Each rib has bone and cartilage parts. Ribs are divided into groups:
- true from I to VII - attached to the sternum;
- false from VIII to X - have a common attachment by a costal arch;
- wavering XI and XII - have free ends and are not attached.
The bony part of the rib (os costale) is a long, spirally curved bone, which distinguishes the head, neck and body. rib head is located at its rear end. It bears an articular surface for articulation with the costal fossae of two adjacent vertebrae. The head goes into rib neck. Between the neck and body, a tubercle of the rib with an articular surface for articulation with the transverse process of the vertebra is visible. (Since the XI and XII ribs do not articulate with the transverse processes of the corresponding vertebrae, there is no articular surface on their tubercles.) Rib body long, flat, curved. It distinguishes between the upper and lower edges, as well as the outer and inner surfaces. On the inner surface of the rib along its lower edge there is a rib groove in which intercostal vessels and nerves are located. The length of the body increases up to the VII-VIII rib, and then gradually decreases. In the 10 upper ribs, the body directly behind the tubercle forms a bend - the angle of the rib.
The first (I) rib, unlike the others, has an upper and lower surface, as well as outer and inner edges. On the upper surface at the anterior end of the first rib, the tubercle of the anterior scalene muscle is noticeable. In front of the tubercle is the groove of the subclavian vein, and behind it is the groove of the subclavian artery.
Rib cage in general (compages thoracis, thorax) is formed by twelve thoracic vertebrae, ribs and sternum. Its upper aperture is limited posteriorly by the 1st thoracic vertebra, laterally by the 1st rib and in front by the manubrium of the sternum. The lower aperture of the chest is much wider. Its border is formed by the XII thoracic vertebra, XII and XI ribs, costal arch and xiphoid process. The costal arches and the xiphoid process form the substernal angle. The intercostal spaces are clearly visible, and inside the chest, on the sides of the spine, there are pulmonary grooves. The back and side walls of the chest are much longer than the front. In a living person, the bony walls of the chest are supplemented by muscles: the lower aperture is closed by the diaphragm, and the intercostal spaces are closed by muscles of the same name. Inside the chest, in the chest cavity, are the heart, lungs, thymus gland, large vessels and nerves.
The shape of the chest has gender and age differences. In men, it expands downward, cone-shaped, and is large in size. The chest of women is smaller, egg-shaped: narrow at the top, wide in the middle and tapering again at the bottom. In newborns, the chest is somewhat compressed from the sides and extended anteriorly.
Rib cage. 1 - upper aperture of the chest (apertura thoracis superior); 2 - sternocostal joints (articulationes sternocostales); 3 - intercostal space (spatium intercostale); 4 - substernal angle (angulus infrasternalis); 5 - costal arch (arcus costalis); 6 - lower aperture of the chest (apertura thoracis inferior)