The ascending aorta (AAo) is a portion of the

aorta The aorta ( ; : aortas or aortae) is the main and largest artery in the human body, originating from the Ventricle (heart), left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at ...

commencing at the upper part of the base of the

left ventricle A ventricle is one of two large chambers located toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs. The blood pumped by a ventricle is supplied by an atrium, an adjacent chamber in t ...

, on a level with the lower border of the third costal cartilage behind the left half of the

sternum The sternum (: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major bl ...

Structure

It passes obliquely upward, forward, and to the right, in the direction of the heart's axis, as high as the upper border of the second right

costal cartilage Costal cartilage, also known as rib cartilage, are bars of hyaline cartilage that serve to prolong the ribs forward and contribute to the elasticity of the walls of the thorax. Costal cartilage is only found at the anterior ends of the ribs, pr ...

, describing a slight curve in its course, and being situated, about behind the posterior surface of the

. The total length is about .

Components

The aortic root is the portion of the aorta beginning at the aortic annulus and extending to the sinotubular junction. It is sometimes regarded as a part of the ascending aorta, and sometimes regarded as a separate entity from the rest of the ascending aorta. Between each commissure of the

aortic valve The aortic valve is a valve in the heart of humans and most other animals, located between the left ventricle and the aorta. It is one of the four valves of the heart and one of the two semilunar valves, the other being the pulmonary valve. ...

and opposite the cusps of the aortic valve, three small dilations called the

aortic sinuses An aortic sinus, also known as a sinus of Valsalva, is one of the anatomic dilations of the ascending aorta, which occurs just above the aortic valve. These widenings are between the wall of the aorta and each of the three cusps of the aortic val ...

. The sinotubular junction is the point in the ascending aorta where the aortic sinuses end and the aorta becomes a tubular structure.

Size

thoracic aorta The thoracic aorta is a part of the aorta located in the thorax. It is a continuation of the aortic arch. It is located within the posterior mediastinal cavity, but frequently bulges into the left pleural cavity. The descending thoracic aorta be ...

diameter greater than 3.5 cm is generally considered dilated, whereas a diameter greater than 4.5 cm is generally considered to be a

thoracic aortic aneurysm A thoracic aortic aneurysm is an aortic aneurysm that presents primarily in the thorax. A thoracic aortic aneurysm is the "ballooning" of the upper aspect of the aorta, above the diaphragm. Untreated or unrecognized they can be fatal due to dissec ...

. Still, the average diameter in the population varies by for example age and sex. The upper limit of

standard reference range In medicine and health-related fields, a reference range or reference interval is the range or the interval of values that is deemed normal for a physiological measurement in healthy persons (for example, the amount of creatinine in the blood, or ...

of the ascending aorta may be up to 4.3 cm among large, elderly individuals.

Relations

At the union of the ascending aorta with the

aortic arch The aortic arch, arch of the aorta, or transverse aortic arch () is the part of the aorta between the ascending and descending aorta. The arch travels backward, so that it ultimately runs to the left of the trachea. Structure The aorta begins ...

the caliber of the vessel is increased, owing to a bulging of its right wall. This dilatation is termed the bulb of the

, and on transverse section presents a somewhat oval figure. The ascending aorta is contained within the

pericardium The pericardium (: pericardia), also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong inelastic connective tissue (fibrous pericardium), ...

, and is enclosed in a tube of the serous pericardium, common to it and the

pulmonary artery A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and ...

. The ascending aorta is covered at its commencement by the trunk of the

and the right auricula, and, higher up, is separated from the sternum by the pericardium, the right pleura, the anterior margin of the right lung, some loose areolar tissue, and the remains of the thymus; posteriorly, it rests upon the left atrium and right pulmonary artery. On the right side, it is in relation with the

superior vena cava The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. It is a large-diameter (24 mm) short length vei ...

and

right atrium The atrium (; : atria) is one of the two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular mitral and tricuspid heart valves. ...

, the former lying partly behind it; on the left side, with the pulmonary artery.

Branches

The only branches of the ascending aorta are the two

coronary arteries The coronary arteries are the arteries, arterial blood vessels of coronary circulation, which transport oxygenated blood to the Cardiac muscle, heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any ...

which supply the heart; they arise near the commencement of the aorta from the aortic sinuses which are opposite the

Clinical significance

' is extensive

atherosclerotic Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by elev ...

calcification of the ascending aorta. It makes

aortic surgery Open aortic surgery (OAS), also known as open aortic repair (OAR), describes a technique whereby an abdominal, thoracic or retroperitoneal surgical incision is used to visualize and control the aorta for purposes of treatment, usually by the repla ...

difficult, especially

aortic cross-clamp An aortic cross-clamp is a surgical instrument used in cardiac surgery to clamp the aorta and separate the systemic circulation from the outflow of the heart. An aortic cross-clamping procedure serves, for example, in the repairing of coarctat ...

ing, and incisions may result in excessive aortic injury and/or

arterial embolism Arterial embolism is a sudden interruption of blood flow to an organ or body part due to an embolus adhering to the wall of an artery blocking the flow of blood, the major type of embolus being a blood clot ( thromboembolism). Sometimes, pul ...

. The ascending aorta segment is of significant due to its susceptibility to

aortic dissection Aortic dissection (AD) occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of the aortic wall, forcing the layers apart. In most cases, this is associated with a sudden onset of agonizing ches ...

, two times more than in the descending aorta. Early detection of dissection is critical because it allows for prompt intervention to prevent potentially life-threatening complications.

Diagnostics

Diagnostic methods such as

echocardiography Echocardiography, also known as cardiac ultrasound, is the use of ultrasound to examine the heart. It is a type of medical imaging, using standard ultrasound or Doppler ultrasound. The visual image formed using this technique is called an ec ...

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

(MRI) and

computed tomography A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

(CT) scans, often with

contrast enhancement A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radioph ...

, are used in the detection of pathology and evaluation of ascending aorta.

Images

Image:Gray490.png, Front view of heart and lungs. Image:Gray505.png, The arch of the aorta, and its branches. File:Thoracic cavity of foetus - great vessels.JPG, Fetal ascending aorta File:Slide7eeee.JPG, Ascending aorta File:Slide12eeee.JPG, Ascending aorta File:Slide8gggg.JPG, Ascending aorta File:Slide2wwww.JPG, Ascending aorta File:Slide5444.JPG, Ascending aorta File:Slide11444.JPG, Ascending aorta File:Ascending aorta.png, Ascending aorta

References

External links

{{Authority control Arteries of the thorax Aorta de:Aorta#Abschnitte