Generality
The aortic arch, or arch of the aorta, is the aorta tract that follows the ascending aorta and precedes the descending aorta.
5-6 centimeters long and 30 millimeters wide, the aortic arch forms a characteristic curve, whose convexity is turned upwards and which places the aorta on the left side of the trachea and esophagus.
The aortic arch is important from the anatomical point of view above all because from it the first branches of the aorta are born; it is, in fact, from the aortic arch which derives, in order, the brachiocephalic trunk, the left common carotid artery and the left subclavian artery.
The aortic arch can be the object of various pathologies, including atherosclerosis, coarctation of the aorta, the double aortic arch and Takayasu's arteritis.
Short review of the aorta
The aorta is the largest and most important artery in the human body.
Originating in the heart (to be precise from the left ventricle of the heart ), this fundamental arterial vessel is provided with numerous ramifications, through which it supplies every district of the human body with oxygenated blood, from the head to the lower limbs, passing through the limbs upper and trunk.
Analyzing it from the beginning, the aorta is didactically divided into two large consecutive sections: the thoracic aorta, occupying the anatomical portion of the thorax, and the abdominal aorta, located in the anatomical portion of the abdomen.
What is the Aortic Arch?
The aortic arch, or arch of the aorta, is the part of the thoracic aorta immediately following the ascending aorta and immediately preceding the descending aorta .
According to other equally valid definitions of aortic arch, the latter would be:
- The continuation of the ascending aorta with a term where the descending aorta begins;
or
- The second important portion of the thoracic aorta after the ascending aorta, which is the first significant portion of the largest artery of the human body.
What are the ascending aorta and the descending aorta?
The ascending aorta is the very first portion of the thoracic aorta, hence the beginning of the aorta; having its origin in the left ventricle of the heart, it faces upwards (and this explains the use of the adjective "ascending") and generally has a length between 5 and 6 centimeters.
The descending aorta, on the other hand, is the third relevant portion of the thoracic aorta; facing downwards (this explains the adjective "descending"), it is in fact the continuation of the aortic arch.
How does the aortic arch appear in graphic representations?
In the classic graphic representations of the aortic arch, the latter is the curved portion of the aorta which, bypassing the complex of the pulmonary arteries, directs the same aorta to pass behind the heart.
Anatomy
An anatomical structure forming part of the so-called upper mediastinum, the aortic arch begins its course at the same level as the dumbbell-sternal joint and the second sternum-costal joint .
The manubrio-sternal joint is the joint that connects the handlebar of the sternum to the body of the sternum (respectively, the top and the central region of the sternum).
The second sterno-costal articulation, on the other hand, is the joint that joins the sternum to the costal cartilage of the second rib (or rib).
5-6 centimeters long and 30 millimeters in diameter, the aortic arch forms a very particular convex upward curve ; in fact, it has a right-left orientation, thanks to which it moves the aorta more towards the left side of the trunk, and a front-back orientation (or ventral-dorsal), through which it places the aorta behind the heart.
The aortic arch terminates, with the beginning of the descending aorta, approximately at the level of the fourth thoracic vertebra .
Branches of the aortic arch
To understand…
The branches of an artery are its branches .
The aortic arch has 3 branches, all of which depart from its upper surface, exactly where it locates its characteristic convexity.
Proceeding from the beginning of the aortic arch, the branches in question are:
- The brachiocephalic trunk (or anonymous artery );
- The left common carotid artery ;
- The left subclavian artery .
BRACHIOCEPHALIC TRUNK
The brachiocephalic trunk is the first large-caliber branch of the aorta.
1.5 cm in diameter and no more than 3.5 cm long, this vascular conduit ends its course with a branch, from which the right common carotid artery and the right subclavian artery originate.
ARTERY CAROTIDE COMMON LEFT (AND COMMON RIGHT CAROTID ARTERY)
The left common carotid artery is the large-caliber artery which, together with the aforementioned right common carotid artery, forms the vascular system responsible for supplying the brain, the face and the elements of the face with oxygenated blood (eg : eyes).
The left common carotid artery rises along the left side of the neck, exactly opposite to the right common carotid artery (which, therefore, rises along the right side of the neck).
LEFT SUCCLAVIA ARTERY (AND RIGHT SUCCLAVIAN ARTERY)
The left subclavian artery is the artery which, together with the right subclavian artery, forms the vascular system responsible for supplying the upper limbs with oxygenated blood.
Obviously, the left subclavian artery follows a path that leads it to the left upper limb, exactly as opposed to what happens to the right subclavian artery (which, therefore, is oriented towards the right upper limb).
Curiosity: how do the succubia arteries continue?
Briefly, both right and left, the subclavian artery continues with the axillary artery, which in turn continues with the brachial artery ; the latter has numerous branches, both collateral and terminal, which take care of oxygenating the proper arm, forearm and hand.
Relationships of proximity of the aortic arch
- Anteriorly and to the left, the aortic arch tightens with the left vagus nerve, the left phrenic nerve, the left lung, the left pleura and the superficial cardiac plexus.
- Posteriorly and to the right, the aortic arch is related to the trachea, the esophagus, the left recurrent laryngeal nerve (or lower left laryngeal nerve), the thoracic duct and the deep cardiac plexus.
- Above, the aortic arch tightens with the thymus and the left brachiocephalic vein.
- Inferiorly, the aortic arch is related to the common pulmonary artery (or pulmonary trunk), the left pulmonary artery (ie the first branch of the common pulmonary artery directed towards the left lung), the arterial ligament (see details underlying), the left recurrent laryngeal nerve, the left main bronchus and the superficial cardiac plexus.
Deepening: What is the arterial ligament?
Remnant of the fetal structure known as the Botallo duct, the arterial ligament is the fibrous structure that connects the aortic arch to the underlying common pulmonary artery.
Histology of the aortic arch
At the cellular (or histological) level, the aortic arch wall has three characteristic cellular layers, which, from the inside to the outside, are: the intimate habit, the medium frock and the adventitious frock.
The intimate habit is the wall layer in direct contact with the lumen of the aortic arch; to constitute it are squamous epithelial cells.
The middle habit is the middle layer of the aortic arch wall; muscle cells and elastic fibers participate in its constitution.
Finally, the adventitious frock is the outermost layer of the aortic arch wall; at its constitution take part connective tissue and, but not always, muscle cells and elastic fibers.
Development
During embryonic development, the aortic arch results from the so-called fourth pharyngeal arch ; other anatomical structures also derive from the latter, including for example the right subclavian artery.
variants
Following certain errors during embryonic development, the aortic arch may undergo a process of abnormal formation, which leads it to assume different appearance than the one described above (ie from what is considered normality). More specifically, these errors during embryonic development can:
- Altering the aortic arch positioning .
Two possible consequences of when the correct positioning of the aortic arch is lacking, are the so-called de- proposed aortic arch, in which the aortic arch is placed to the right of the trachea (rather than to the left), and the so-called double aortic arch, in which the the aortic arch divides into two and develops to the right and left of the trachea and esophagus.
or
- Modify the arrangement of the three classic branches of the aortic arch.
The wrong formation of the aortic arch branch system can cause two distinct situations: the birth of the left common carotid artery in the same point from which the brachiocephalic trunk ( bovine aortic arch ) originates or the birth of the left common artery in a point of the brachiocephalic trunk ( bicarotic trunk ).
or
- Induce, on the aortic arch, the generation of other branches, in addition to the three classics.
Among the other branches to the classical ones, which can be formed in a completely anomalous way on the aortic arch, are the so-called Neubauer thyroid artery (whose seat is between the brachiocephalic trunk and the left common carotid artery) and the left vertebral artery ( whose seat is between the left common carotid artery and the left subclavian artery).
or
- Provoke excessive narrowing of the lumen of the aortic arch.
In medicine, this condition is an example of coarctation of the aorta .
Curiosity: how many people have abnormalities in the branches of the aortic arch?
According to statistics, the bovine aortic arch and the bicarotic trunk are observable, respectively, in 15% and 10% of the general population.
This means that in 75 people out of 100 the aortic arch branch system is normal.
Function
Through its three branches, the aortic arch covers the important function of channeling oxygenated blood from the heart towards the head, neck and upper limbs.
Thus, from the aortic arch depends the blood supply of the brain, face, organs of the face, neck, shoulders, arms properly called, forearms and hands.
diseases
The aortic arch may be at the center of various pathological states; among these pathological states, include:
- The coarctation of the aorta and the double aortic arch, that is two of the possible anomalies of the aortic arch related to a wrong embryonic development of the latter;
- Atherosclerosis to the damage of the aorta, in particular of the aortic arch;
- Takayasu's arteritis .
Coarctation of the aorta
Coarctation of the aorta is a congenital condition, characterized by narrowing of the aorta and the consequent impairment of blood flow within the aorta.
The aortic arch is often associated with coarctation of the aorta, because it represents in many clinical cases the site of the narrowing (the narrowing sees the involvement of the arterial ligament).
Those suffering from coarctation of the aorta develop hypertension in the upper limbs, hypotension in the lower limbs, left ventricular hypertrophy and hyperperfusion of the abdominal organs, and manifest symptoms such as headache, chest pain, cold extremities, fatigue and intermittent claudication .
Double aortic arch
In situations of double aortic arch, the aortic arch develops around the trachea and esophagus like a ring and causes the compression of these organs; from the compression of the trachea and esophagus springs a tracheal and esophageal obstruction, which is responsible for respiratory problems and problems with swallowing food.
Atherosclerosis
Atherosclerosis is the phenomenon of hardening of medium and large caliber arteries (the aortic arch and its branches are among these), which induces the formation of atheromas over time on the inner wall of the arterial vessels just mentioned.
The atheros or atherosclerotic plaques are aggregates of lipid material (cholesterol), protein and fibrous which, due to the position they occupy, prevent the normal blood flow inside the arteries; moreover, they can be the object of inflammatory processes, which cause their fragmentation and dispersion into other blood vessels - this time smaller - with consequent occlusive effects.
To promote the process of atherosclerosis are numerous factors, including: hypertension, hypercholesterolemia, high triglycerides, cigarette smoking and smoking in general, diabetes, obesity and some inflammatory diseases such as systemic lupus erythematosus .
Takayasu arteritis
Takayasu's arteritis is a vasculitis of autoimmune origin, which causes inflammation of the major arteries, such as the ascending aorta, the aortic arch, the branches of the aortic arch, the descending aorta, the pulmonary artery and the its main branches.
