The aorta is the largest vessel in the body both in length and diameter, and in terms of blood flow volume, therefore proper blood supply to all organs and systems of the body depends on it. The pathology of this artery, the largest in the human body, negatively affects the work of all organs, the vessels to which branch below the level of the lesion.
Anatomy of the aorta
Conventionally, this large vessel is divided into three parts, based on its direction:
- Upstream department.
- Aortic arch, the anatomy of which is considered separately.
- Descending part. This section is the longest. It ends at the approach to the fourth lumbar vertebra. This is where the common iliac arteries begin, into which the abdominal aorta divides.
Anatomy and topography
The ascending aorta emerges from the left ventricle. Having reached the second rib, it passes into the so-called arc, which, curving to the left, at the level of the fourth vertebra of the thoracic spine passes into the descending part.
Aortic anatomy and locationits departments and main branches relative to other internal organs at various levels is of great importance in studying the structure of the chest and abdominal cavities.
Thoracic
Starting at the level of the fourth thoracic vertebrae, the thoracic segment of the aorta is directed almost vertically down, located in the region of the posterior mediastinum. To the right of the aorta in this place lie the thoracic duct and the unpaired vein; on the left - the parietal pleura.
Abdomen
This section begins when the aortic vessel passes through the corresponding hole in the diaphragm and extends to the level of the fourth lumbar vertebra. In the abdominal cavity, the aorta anatomy has its own peculiarity: it lies in the retroperitoneal cellular space, on top of the bodies of the lumbar vertebrae, surrounded by the following organs:
- to the right of it lies the inferior vena cava;
- on the anterior side of the abdominal aorta adjoin the posterior surface of the pancreas, the horizontal segment of the duodenum, and part of the root of the mesentery of the small intestine.
After reaching the level of the fourth lumbar vertebrae, the abdominal aorta divides into two iliac arteries. They provide blood supply to the lower extremities (this place is called a bifurcation, a bifurcation of the aorta, and is its end).
In accordance with the location of the parts of this large vessel, the anatomy of the aorta and its branches is considered by department.
Ascending branches
This is the initial section of the vessel. Its duration is short: from the left ventricleheart to the cartilage of the second rib on the right.
At the very beginning of the ascending aorta, the right and left coronary arteries branch off from it, the area of the blood supply of which is the heart.
Aortic arch branches
The anatomy of the arch has the following feature: large arteries originate from its convex part, carrying blood supply to the skull and upper limbs. The concave part gives off small branches that do not have a permanent location.
The following branches depart from the convex side of the aortic arch (from right to left):
- brachiocephalic trunk ("brachiocephalic");
- left common carotid artery;
- left subclavicular artery.
The concave part of the arch gives off thin arterial vessels suitable for the trachea and bronchi. Their number and location may vary.
Descendant branches
The descending aorta, in turn, is divided into departments:
- Thoracic, located above the diaphragm;
- Abdomen below the diaphragm.
Thoracic:
- Parietal arterial vessels for blood supply to the chest wall: superior phrenic arteries, branching surfaces of the diaphragm from the side of the chest cavity, and posterior intercostal arterial vessels supplying blood to the intercostal and rectus abdominal muscles, mammary gland, spinal cord, and soft tissues back.
- The visceral vessels branching from the thoracic region branch in the organs of the posterior mediastinum.
Abdomen:
- Parietal branches branching in the walls of the abdominal cavity (four pairs of lumbar arteries supplying the muscles and skin of the lumbar region, abdominal walls, lumbar spine and spinal cord) and the lower surface of the diaphragm.
- The visceral arterial branches going to the organs of the abdominal cavity are paired (to the adrenal glands, kidneys, ovaries and testicles; the names of the arteries correspond to the names of the organs supplying them with blood) and unpaired. The names of the visceral arteries correspond to the names of the organs they supply.
The structure of the vessel wall
The concept of "anatomy of the aorta" includes the structure of the wall of this largest arterial vessel in the body. The structure of its wall has certain differences from the structure of the wall of all other arteries.
The structure of the aortic wall looks like this:
- Inner sheath (intima). It is a basement membrane lined with endothelium. The endothelium actively responds to signals received from the blood circulating in the vessel, transforms them and transmits them to the smooth muscle layer of the vascular wall.
- Medium shell. This layer in the aorta consists of circularly located elastic fibers (unlike other arterial vessels in the body, where collagen, smooth muscle, and elastic fibers are represented - without a clear predominance of any of them). The anatomy of the aorta has a feature: the middle shell of the aortic wall is formed by the mainlike elastic fibers. The function of the middle shell is to maintain the shape of the vessel, and also provides its motility. The middle layer of the vascular wall is surrounded by an interstitial substance (fluid), the main part of which penetrates here from the blood plasma.
- Adventitia (outer shell of the vessel). This connective tissue layer contains mainly collagen fibers and perivascular fibroblasts. It is permeated with blood capillaries and contains a large number of endings of autonomic nerve fibers. The perivascular connective tissue layer is also a conductor of signals directed to the vessel, as well as impulses emanating from it.
Functionally, all layers of the vascular wall are interconnected and are able to transmit an information impulse to each other - both from the intima to the middle layer and adventitia, and in the opposite direction.
