The descending thoracic aorta is a part of the

aorta The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes ...

located in the

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

. It is a continuation of 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 ...

. It is located within the posterior mediastinal cavity, but frequently bulges into the left

pleural cavity The pleural cavity, pleural space, or interpleural space is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication bet ...

. The descending thoracic aorta begins at the lower border of the fourth

thoracic vertebra In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

and ends in front of the lower border of the twelfth thoracic vertebra, at the

aortic hiatus The aortic hiatus is a hole in the diaphragm. It is the lowest and most posterior of the large apertures. It is located approximately at the level of the twelfth thoracic vertebra (T12). Structure Strictly speaking, it is not an aperture in the ...

in the diaphragm where it becomes the abdominal aorta. At its commencement, it is situated on the left of the vertebral column; it approaches the median line as it descends; and, at its termination, lies directly in front of the column. The descending thoracic aorta has a curved shape that faces forward, and has small branches. It has a radius of approximately 1.16 cm.

Structure

The descending thoracic aorta is part of the

, which has different parts named according to their structure or location. The descending thoracic aorta is a continuation of the

descending aorta In human anatomy, the descending aorta is part of the aorta, the largest artery in the body. The descending aorta begins at the aortic arch and runs down through the chest and abdomen. The descending aorta anatomically consists of two portions o ...

and becomes the abdominal aorta when it passes through the diaphragm. The initial part of the

, the ascending aorta, rises out of the left ventricle, from which it is separated by 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. The ...

. The two

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

of the heart arise from the aortic root, just above the cusps of the

. The aorta then arches back over the right

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 t ...

. Three vessels come out of the

: the

brachiocephalic artery The brachiocephalic artery (or brachiocephalic trunk or innominate artery) is an artery of the mediastinum that supplies blood to the right arm and the head and neck. It is the first branch of the aortic arch. Soon after it emerges, the brachioce ...

, the left

common carotid artery In anatomy, the left and right common carotid arteries (carotids) (Entry "carotid"
in
subclavian artery In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplie ...

. These vessels supply blood to the

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...

neck The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...

and

upper limb The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulde ...

s. Behind the descending thoracic aorta is the

vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordata, ...

and the

hemiazygos vein The hemiazygos vein (vena azygos minor inferior) is a vein running superiorly in the lower thoracic region, just to the left side of the vertebral column. Structure The hemiazygos vein and the accessory hemiazygos vein, when taken together, essen ...

. To the right is the

azygos veins The azygos vein is a vein running up the right side of the thoracic vertebral column draining itself towards the superior vena cava. It connects the systems of superior vena cava and inferior vena cava and can provide an alternative path for blood ...

and

thoracic duct In human anatomy, the thoracic duct is the larger of the two lymph ducts of the lymphatic system. It is also known as the ''left lymphatic duct'', ''alimentary duct'', ''chyliferous duct'', and ''Van Hoorne's canal''. The other duct is the right ...

, and to the left is the left

pleura The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls. The inner pleura, called the visceral pleura, covers the surface of each lung and dips b ...

and lung. In front of the descending thoracic aorta lies the root of the left

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

, the

pericardium The pericardium, 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 connective tissue (fibrous pericardium), and an inner layer made of ...

, the

esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...

, and the diaphragm. The

, which is covered by a nerve

plexus In neuroanatomy, a plexus (from the Latin term for "braid") is a branching network of vessels or nerves. The vessels may be blood vessels (veins, capillaries) or lymphatic vessels. The nerves are typically axons outside the central nervous syste ...

lies to the right of the descending thoracic aorta. Lower, the esophagus passes in front of the aorta, and ultimately is situated on the left.

Function

The

is an

artery An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pul ...

that conveys oxygenated

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...

from the

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...

to other parts of the body. It is one of the largest arteries in the body. The aorta gives off several paired branches as it descends. In descending order, these include the *

Bronchial arteries In human anatomy, the bronchial arteries supply the lungs with nutrition and oxygenated blood. Although there is much variation, there are usually two bronchial arteries that run to the left lung, and one to the right lung and are a vital part o ...

* Mediastinal arteries *

Esophageal arteries Esophageal (Oesophageal in British English) arteries are a group of arteries from disparate sources supplying the esophagus. The blood supply to the esophagus can roughly be divided into thirds, with anastamoses between each area of supply. More s ...

*Pericardial arteries *

Superior phrenic arteries The superior phrenic arteries are small and arise from the lower part of the thoracic aorta. They are distributed to the posterior part of the upper surface of the diaphragm, and anastomose with the musculophrenic and pericardiacophrenic arteries. ...

Note: The

posterior intercostal arteries The intercostal arteries are a group of arteries that supply the area between the ribs ("costae"), called the intercostal space. The highest intercostal artery (supreme intercostal artery or superior intercostal artery) is an artery in the huma ...

are branches that originate throughout the length of the posterior aspect of the descending thoracic aorta.

Clinical significance

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 severe chest or ...

Additional images

File:Gray503.png, Transverse section of thorax, showing relations of pulmonary artery. File:Gray505.png, The arch of the aorta, and its branches. File:Aorta_Anatomy.jpg, Schematic of the thoracic aorta, showing major branches

References

External links

UCC
{{DEFAULTSORT:Thoracic Aorta Aorta Arteries of the thorax