Intraosseous arteries.

Intraosseous arteries.

According to the structure, function and development of the long tubular bones, the latter are obtained: the diaphyseal arteries are the main one (a. Nutritia, or rather a. Diaphyseos princeps), enters the middle part of the diaphysis and is divided into r. proximalis and r. distalis, of which the proximal branch supplies blood to the proximal part of the diaphysis, and the distal branch – to the distal one. At the same time, in the long tubular bones, the main diaphyseal arteries enter not strictly in the middle of the bone and not perpendicular to its long axis, but obliquely. Additional (aa. Diaphyseos accessoriae) penetrate the bone at the ends of the diaphysis. Diaphyseal arteries feed the diaphysis from the inside, and the cortical artery receives the cortical arteries from the periosteum. The presence of two systems of the arteries of the diaphysis explains the possibility of a purulent process affecting one layer of the diaphysis while maintaining the other.

In addition to the diaphyseal arteries, the long tubular bone is also supplied by the arteries that are included in the metaphysis (metaphyseal arteries), the epiphyses (epiphyseal arteries), and the apophyses (apophyseal arteries). Epiphyseal cartilage first separates the vessels of the epiphysis from the vessels of the metaphysis; as sostostirovaniya all vessels are interconnected, forming a single system for a given bone. In the short tubular bones with one epiphysis (metacarpus and tarsus), there is one system of epiphyseal arteries. In the short spongy bones (vertebrae, wrist, tarsus, sternum), the vessels enter from different sides, heading towards the points of origin of ossification.

The arteries of the ligaments run along the bundles of connective tissue and along with them are located perpendicular to the corresponding axis of rotation. Muscle arteries go first along the functional axis of the muscle, then penetrate into the perimysium internum and follow it in parallel with the bundles of muscle fibers, giving them perpendicular branches, forming loops stretched along the muscle bundles.

The organs of the lobed structure (lungs, liver, kidneys) of the arteries enter the center of the organ and diverge (three-dimensional) to the periphery of the organ lobes and lobes, respectively.

Patterns of the course of the arteries from the maternal trunk to the organ.

Patterns of the course of the arteries from the maternal trunk to the organ.

With the development of the arterial system, a primary vascular network first appears. In the extreme part of this network, more difficult conditions are created for blood circulation than in those parts that connect the organ and the maternal trunk in the shortest possible way. Therefore, one vessel lying on a straight line between the maternal trunk and the organ is preserved, while the others empty and it turns out that:

1. Arteries travel along the shortest distance, i.e. approximately in a straight line connecting the mother’s trunk with the organ. Therefore, each artery gives branches to nearby organs. This explains that the first branches of the aorta upon its exit from the heart are the arteries to the heart itself. This also explains the order of branching branches, determined by the tab and the location of organs. For example, the branches from the abdominal aorta first go to the stomach (from truncus celiacus), then to the small intestine (a. Mesenterica superior) and, finally, to the large intestine (a. Mesenterica inferior). Or, first, the arteries to the adrenal gland (a. Suprarenalis media), and then to the kidney (a. Renalis). In this case, it is the place of the laying of the organ that matters, and not its final position, which explains that a. testicula-fig does not depart from a. femoralis, and from the aorta, near which the testicle has developed. On the contrary, the scrotum, which originated in the area of ​​the external genital organs, receives the arteries at the site of aa. pudendae externae, originating from the nearest large trunk, a. lemoralis. Knowing the law of the shortest distance and the history of development, one can always determine those organs and those branches to them that depart from a given artery.

2. Arteries are located on the flexion surfaces of the body, because when unbending the vascular tube stretches and collapses. This explains, for example, the location of the common carotid artery on the front surface of the neck, the large arteries of the hand on the palm side. In the lower limb, where the flexion side is located in the hip joint in the front, and in the knee – in the back, the femoral artery passes from the front surface of the thigh to the rear, acquiring a spiral stroke.

3. Arteries are located in sheltered places in the gutters and channels formed by bones, muscles and fascia that protect blood vessels from compression. Since the four-legged open and unprotected is the dorsal side of the body, the vessels are located on the ventral side, which is preserved in humans. This explains the location of the aorta and its branches in front of the spinal column, and the arteries in the neck and extremities – mainly on the front surface. There are no large arteries on the back.

4. Arteries enter the organ on a concave medial or internal surface facing the power source. Therefore, all the gates of the viscera are on a concave surface directed toward the midline, where the aorta lies, sending branches to them.

5. Arteries form adaptations according to the function of the organ:

a) vascular networks, rings, and arcuate anastomoses are observed in organs associated with movement. Thus, in the area of ​​the joints, the articular network, the rete articulare, is formed from the branches of large arteries passing by them, due to which blood flows to the joint, despite the fact that during its movements a part of the vessels is compressed or stretched. Moving entrails that change the size and shape, such as the stomach and intestines, have a large number of annular and arcuate anastomoses;

b) the caliber of the arteries is determined not only by the size of the organ, but also by its function. Thus, the renal artery is not inferior in its diameter to the mesenteric, supplying the long intestine, as it carries blood to the kidney, whose urinary function requires a large flow of blood. Thyroid arteries are also more laryngeal arteries, because a hormone-producing thyroid gland requires more blood than blood supply to the larynx;

c) in connection with this, all endocrine glands receive multiple sources of nutrition. For example, the same thyroid gland – from all nearby large arteries: carotid, subclavian and aorta; adrenal gland – from a. phrenica inferior (a. suprarenalis superior), from the aorta (a. suprarenalis media) and from the renal artery (a. suprarenalis inferior).

Patterns of distribution of arteries

Patterns of distribution of arteries

The arterial system reflects in its structure the general laws of the structure and development of the organism and its individual systems. By supplying blood to various organs, it corresponds to the structure, function, and development of these organs. Therefore, the distribution of arteries in the human body is subject to certain laws, which can be divided into the following groups.

Extraorganic arteries

1. Accordingly, the grouping “… the whole body around the nervous system” arteries are located along the nerve tube and nerves. So, parallel to the spinal cord is the main arterial trunk – the aorta and aa. spinales anterior et posterior. Each segment of the spinal cord corresponds to segmental rr. spinales of the corresponding arteries. In addition, arteries are initially laid in connection with the main nerves: for example, on the upper limb due to n. medianus, on the bottom – with n. ischiadicus. Therefore, in the future, they go along with the nerves, forming neurovascular bundles, which also include veins and lymphatic vessels. There is a relationship between nerves and vessels (“neurovascular connections”), which contributes to the implementation of a single neurohumoral regulation.
2. Accordingly, the division of the body into the organs of plant and animal life of the artery is divided into parietal – to the walls of the body cavities and visceral – to their contents, i.e., to the viscera. Example: parietal and visceral branches of the descending aorta.
3. Each limb receives one main trunk: for the upper limb – a. subclavia, for the bottom – a. ilica externa.
4. The arteries of the trunk maintain a segmental structure: aa. intercostales posteriores, lumbales, rr. spinales and others …
5. Most of the arteries are located on the principle of bilateral symmetry: the paired artery of the soma and the viscera. Departure from this principle is associated with the development of arteries within the primary mesenteries.
6. Arteries go along with other parts of the vascular system – with veins and lymphatic vessels, forming a common vascular complex. The structure of this complex should include thin and long additional arteries and veins parallel to the main and components of the so-called para-arterial and para-venous bed of the vessels.
7. Arteries go according to the skeleton, which forms the basis of the body. So, along the spinal column is the aorta, along the ribs – intercostal arteries. In the proximal parts of the extremities that have one bone (shoulder, hip), there is one main vessel (brachial, femoral artery); in the middle sections, with two bones (forearm, lower leg), there are two main arteries (radial and ulnar, major and minor shin); finally, in the distal regions, the hands and the foot, which have a ray structure, the arteries go according to each finger ray.

Formation of the inferior vena cava

Formation of the inferior vena cava

The formation of the inferior vena cava is associated with the appearance of anastomoses between the posterior cardinal veins. One anastomosis, located in the iliac region, drains blood from the left lower extremity to the right posterior cardinal vein; as a result, the segment of the left posterior cardinal vein, located above the anastomosis, is reduced, and the anastomosis itself is transformed into the left common iliac vein. The right posterior cardinal vein at the site before the confluence of the anastomosis (which has become the left common iliac vein) is converted into the right common iliac vein, and from the site of the junction of both iliac veins to the confluence of the renal veins develops into the secondary inferior vena cava.

The rest of the secondary inferior vena cava is formed from the unpaired primary inferior vena cava flowing into the heart, which connects to the right inferior cardinal vein at the confluence of the renal veins (there is a 2nd anastomosis between the cardinal veins that drains blood from the left kidney). Thus, the finally formed inferior vena cava is composed of 2 parts: from the right posterior cardinal vein (before the confluence of the renal veins) and from the primary inferior vena cava (after its confluence). Since in the inferior vena cava the blood is drained from the entire caudal half of the body into the heart, the value of the posterior cardinal veins weakens, they lag behind in development and turn into v. azygos (right posterior cardinal vein) and in v. hemiazygos and v. hemiazygos accessoria (left posterior cardinal vein). V. hemiazygos falls into v. azygos through the 3rd anastomosis developing in the thoracic region between the former posterior cardinal veins. The portal vein is formed due to the transformation of the yolk veins, through which blood from the yolk sac enters the liver. Vv. omphalomesentericae in the space from the confluence of the mesenteric vein to the gate of the liver into the portal vein.

The development of veins.

The development of veins.

At the beginning of the placental circulation, when the heart is in the cervical region and not yet divided by partitions into the venous and arterial halves, the venous system has a relatively simple device. Large veins pass along the body of the embryo: in the region of the head and neck, the anterior cardinal veins (right and left) and in the rest of the body, the right and left posterior cardinal veins. Approaching the venous sinus of the heart, the anterior and posterior cardinal veins on each side merge to form common cardinal veins (right and left), which, having at first strictly transverse course, flow into the venous sinus of the heart. Along with the paired cardinal veins, there is another unpaired venous trunk – the primary vena cava inferior, which also flows into the venous sinus in the form of a small vessel. Thus, at this stage of development, three venous trunks flow into the heart: paired common cardinal veins and unpaired primary inferior vena cava.

Further changes in the location of the venous trunks are associated with the displacement of the heart from the cervical region downwards and the division of its venous part into the right and left atria. Due to the fact that after the separation of the heart, both common cardinal veins flow into the right atrium, the blood flow in the right common cardinal vein is in more favorable conditions. In this regard, an anastomosis appears between the right and left anterior cardinal veins, through which blood flows from the head into the right common cardinal vein. As a result, the left common cardinal vein ceases to function, its walls collapse and it is obliterated, with the exception of a small part, which becomes the coronary sinus of the heart, sinus coronarius cordis. The anastomosis between the anterior cardinal veins gradually increases, turning into a vena brachiocephalica sinistra, and the left anterior cardinal vein below the anastomosis is obliterated. Two vessels form from the right anterior cardinal vein: a part of the vein above the confluence of the anastomosis turns into a vena brachiocephalica dextra, and a part below it together with the right common cardinal vein is converted into the superior vena cava, collecting blood from the entire cranial half of the body. If an anastomosis is described as underdeveloped, an abnormal development is possible in the form of two superior vena cava.

Ventral aorta

Ventral aorta

Both ventral aorta in the area between the fourth and third aortic arcs are converted into common carotid arteries, aa. carotides communes, and due to the above transformations of the proximal ventral aorta, the right common carotid artery turns out to be extending from the brachiocephalic trunk, and the left one directly from the arcus aortae. In the future, the ventral aorta is transformed into the external carotid artery, aa. carotides externae.

The third pair of aortic arches and the dorsal aorta in the segment from the third to the first branchial arch develop into the internal carotid arteries, aa. carotides internae, bbm, and it is explained that the internal carotid arteries lie more laterally in the adult than the external. The second pair of aortic arches turns into aa. linguales et pharyngeae, and the first pair – in the maxillary, facial and temporal arteries. In violation of the normal course of development, various anomalies arise.

From the dorsal aorta, a series of small paired vessels arises, running in the dorsal direction on both sides of the neural tube. Since these vessels diverge at regular intervals into the loose mesenchymal tissue located between the somites, they are called the dorsal intersegmental arteries. In the neck, on both sides of the body, they are joined early by a series of anastomoses, forming longitudinal vessels – the vertebral arteries.

At the level of the 6th, 7th and 8th cervical intersegmental arteries, the kidneys of the upper extremities are laid. One of the arteries, usually the 7th, grows into the upper limb and increases with the development of the arm, forming the distal subclavian artery (its proximal part develops, as already indicated, on the right of the 4th aortic arch, on the left grows from the left dorsal aorta, which the 7th intersegmental arteries connect).

Subsequently, the cervical intersegmental arteries are obliterated, as a result of which the vertebral arteries are derived from the subclavian.

Thoracic and lumbar intersegmental arteries give rise to aa. intercostales posteriores and aa. lumbales.

The abdominal visceral arteries develop partly from aa. omphalomesentericae (yolk-mesenteric circulation) and part of the aorta.

Arteries of the limbs were originally laid along the nerve trunks in the form of loops.

Some of these loops (along the n. Femoralis) develop into the main arteries of the extremities, others (along the n. Medianus, n. Ischiadicus) remain companions of nerves.