Function and structure of the aortic arch and its branches

The blood supply to the human body is provided by a pumping option of the heart and two circles of hemodynamics. The aorta is the functional beginning of the great circle, which starts from the left ventricle. The vessel is characterized by the largest lumen diameter (2.5-3 cm), wall density and the number of elastic fibers. In the thoracic cavity, the aorta passes through three sections - ascending, arcing and descending. The initial segment of the vessel provides blood delivery to the vital organs - the brain, heart and lungs.

Anatomical structure of the aortic arch

The aortic arch is the intermediate part of the vessel, which is located between the bulb (located in the pericardial sac) and the descending section adjacent to the spinal column. The highest point of the segment is projected onto the edge of the sternum handle, where pulsation is noted with pathologies.

The aortic arch with its convex part facing upwards, with its concave part facing downwards. In the chest cavity, the vessel intersects with the left main bronchus and passes into the descending section at the level of the fourth vertebra.

Topographic anatomy distinguishes three sections of the arc, the characteristics of which are presented in the table:

Section of a vessel	Key structures
Elementary	Superior vena cava on the right edge
Average	in front - the thymus gland, lymph nodes and adipose tissue; outside - phrenic and vagus nerves; from below - arterial ligament (in newborns - Botall's duct); behind - trachea, thoracic duct, esophagus, recurrent laryngeal nerve
Terminal (end)	The isthmus of the aorta in the junction area (narrowed section), where coarctation, stenosis and other pathologies develop

The arterial ligament is a collapsed vessel (Botall's duct), which in the prenatal period connected the aorta and the pulmonary trunk.

The middle section of the aorta provides blood supply to the head, neck and chest cavity through the main branches and outgoing small arteries. The characteristics of the vessels are presented in the table:

Branch of the aorta	Localization
Brachiocephalic trunk	Along the anterior surface of the trachea, shifting to the right of the main trunk. Forks at the level of the outer edge of the sternocleidomastoid muscle
Left common carotid artery	Goes up and to the left to the side of the neck
Left subclavian artery	It is part of the neurovascular bundle located behind the collarbone. Continues to the armpit

Histological characteristics - elastic type artery, consisting of three layers:

internal (intima) - a smooth membrane, the surface of which prevents thrombus formation;
medium (media) - a large number of elastic-type fibers that support the tone of the vessel and the density of the wall (protection against rupture at high pressures);
outer (adventitia) - a thin connective tissue sheath.

Functions

The aortic arch and its branches provide the delivery of oxygenated blood to other arterial trunks, presented in the table:

Vessels	Blood supply area
Carotid arteries	muscles, skin and subcutaneous tissue of the head and neck; thyroid; pharynx, larynx; tongue, floor of the mouth; behind the ear, submandibular salivary glands; brain (hemispheres, cerebellum, bridge, Turkish saddle); ear and eye structures (nerves, mucous membranes, lacrimal glands)
Subclavian arteries	back and medulla oblongata; muscles of the occipital region; thyroid gland (lower and unnamed arteries); the front surface of the chest wall; breast; thymus gland (thymus); pericardium; diaphragm; upper limbs

Additional functions of the vessel:

discharge of blood from the pulmonary trunk during intrauterine development (with a closed pulmonary circulation);
maintaining the normative indicators of blood pressure.

Diagnosis of pathology

Vascular pathologies are one of the most common causes of disability in young people. The establishment of a clinical diagnosis in case of aortic lesion requires additional research methods, presented in the table:

Survey name	Method essence	What allows you to determine
Duplex scanning (ultrasound) of the aortic arch	Performs a special high-frequency narrow beam transducer. The patient lies on his left side. The gel-lubricated transducer is applied to the desired location. The method is based on the ability of tissues to reflect waves of the ultrasound spectrum (due to the different density of the walls, erythrocytes). After processing the received information, the ultrasonic device converts the indicators into a two-dimensional image of the vessel and the movement of blood cells. No specific training is required.	elements of the contents of the vessel; the presence, speed and direction of blood flow; the state of the vessel wall: thickness, integrity, presence of additional formations
Aortography	Radiopaque diagnostic method. Apply local anesthesia at the intended site of catheter insertion. Most often, the femoral artery is used for the procedure. After a puncture, a thin probe-guide is inserted into the lumen of the peripheral vessel, along which the catheter moves. The device is guided to the aortic arch under X-ray control. When the catheter is localized in the required area, a contrast agent (dye) is injected into the lumen of the vessel. Contrasts do not differ in rheological properties from blood, which makes it possible to objectively assess the movement of fluid in the vessels. Take a series of desired shots. Preparation: 8 hours before the procedure, it is forbidden to eat food.	narrowing (congenital or due to atherosclerotic process); blockages; aneurysms
Multispiral computed tomography - (MSCT)	X-ray examination using a contrast agent. The patient lies down on a special couch. Contrast is injected intravenously. The essence of the method is in simultaneous shooting from several devices located opposite the radiation source. The device takes the required number of pictures, which are processed by the program. The end result of the survey is a three-dimensional dynamic diagram of the area. Preparation: last meal at least 8 hours before the procedure.	arch anatomy anomalies; coarctation; aneurysm; stratification; stenosis; occlusion (occlusion of the lumen of the artery); arteritis (inflammation of the vessel wall); traumatic ruptures
Magnetic resonance imaging (MRI)	An image is obtained by visualizing the movement of hydrogen atoms (the human body) in a strong electromagnetic field. The advantage of the method is safety (non-ionizing radiation), accuracy and information content. Preparation: do not eat 2 hours before the examination.	congenital and acquired defects; atherosclerotic lesions; vasculitis; stratification; aneurysm

The choice of method is determined by the patient's complaints and age:

children are recommended ultrasound;
for adults, the "gold standard" is an MRI study.

Before using contrast agents, the doctor must necessarily conduct tests for the presence of allergic reactions to dyes. Ignoring the order leads to dangerous consequences for life and health.

Contraindications to the appointment of contrast methods:

allergy to dyes (the most common preparations contain iodine);
renal failure;
breastfeeding (allowed 48 hours after the procedure);
blood clotting pathologies (hemophilia, thrombocytopathy and others);
serious conditions of the patient (post-resuscitation illness, shock, agony);
thyrotoxicosis;
type II diabetes mellitus;
high levels of creatinine in the blood (a marker of impaired renal excretory function).

Major diseases of the aortic arch

Features of the structure and functions of the aortic arch, high pressure and turbulent blood flow contribute to the frequent formation of disorders. The most common pathologies and characteristic changes are presented in the table:

Disease	Short description
Nonspecific aortoarteritis (Takayasu syndrome)	Vasculitis is an inflammatory disease of autoimmune origin. Leads to vascular damage, overgrowth in connective tissue and overlap of the lumen
"Neck arch"	Congenital lengthening of the aortic arch
Atherosclerosis	The appearance on the vessel wall of lipid plaques, prone to destabilization and rupture. Main reasons: passive lifestyle; smoking; excessive consumption of foods high in fat; hereditary predisposition. Sclerosis leads to aortic stenosis, dissection and aortic aneurysm
Coarctation	Congenital malformation, manifested as segmental narrowing of the aorta. It is more often located in the area of transition of the arc to the descending part. Requires surgical treatment
Hypoplasia	Underdevelopment of the tissues of the vessel in the womb. Surgical intervention required
Aneurysm	Local expansion of the vessel site due to wall weakness. Requires planned surgical treatment due to the risk of sudden rupture and massive internal bleeding
Right arc	Violation of the formation of organs in the embryonic period: the aortic arch turns not to the left, but to the right, spreads over the right bronchus. In most cases, no treatment is required
Calcification	Accumulation of calcium salts and hardening of the artery wall. The vessel becomes less elastic, fragile, which often leads to rupture
Double arc	A congenital malformation characterized by a bifurcation of the aorta: one arch runs in front of the trachea and esophagus; the other is behind. The departments are interconnected. Pathology requires surgery
Layering	Rupture of the aorta at the site of the aneurysm. The prognosis depends on the degree of damage. High mortality rate

Conclusions

The arcuate part of the aorta is a small section (length - up to 10 cm) of the vessel, which provides oxygenated blood to half of the human body. Features of the structure, topography and early laying in the embryonic period are the reasons for the frequent development of pathologies of the region. Diseases of the arch are accompanied by a high risk of complications and death, therefore, they require accurate diagnostic methods for an early start of treatment.