Azygos vein

Azygos vein

Infobox Vein
Name = PAGENAME
Latin = vena azygos
GraySubject = 172
GrayPage = 667


Caption = Superior vena cava, inferior vena cava, azygos vein and their tributaries. (Vena azygos labeled at center.)


Caption2 = POSTERIOR VIEW: The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind. (Azygos vein labeled at bottom left.)
DrainsFrom =
Source = superior intercostal vein
DrainsTo = superior vena cava
Artery =
MeshName = Azygos+Vein
MeshNumber = A07.231.908.106
DorlandsPre = v_05
DorlandsSuf = 12849551

The azygos vein is a vein running up the right side of the thoracic vertebral column. It can also provide an alternate path for blood to the inferior vena cava.

tructure

The azygos vein transports deoxygenated blood from the posterior walls of the thorax and abdomen into the superior vena cava vein. The anatomy of this blood vessel can be quite variable. In some rare variations for example, it also drains thoracic veins, bronchial veins and even gonadal veins. The vein is so named because it has no symmetrically equivalent vein on the left side of the body.

It is formed by the union of the ascending lumbar veins with the right subcostal veins at the level of the 12th thoracic vertebra, ascending in the posterior mediastinum, and arching over the right main bronchus at the root of the right lung to join the superior vena cava. This "arch of the azygos vein" ("arcus venae azygou") is an important anatomic landmark.

Its tributaries, apart from its main tributary, the hemiazygos vein, are the bronchial veins, pericardial veins, and posterior right intercostal veins. It communicates with the vertebral venous plexuses.

Azygos venous system

The azygos system of veins is considered to be the azygos vein, along with its left-sided counterparts, the hemiazygos vein and the accessory hemiazygos vein. Together, they form an anastomosis between the superior vena cava to the inferior vena cava.

It can be noted that the azygos system of veins exists because the superior vena cava and the inferior vena cava are not continuous. While the aorta travels downward (continuously) through the mediastinum, supplying blood to the intercostal spaces, the vena cava does not exist at the level of the heart. Thus, the azygos venous system makes up for this deficiency of the venae cavae.

Etymology

The Greek root "zyg" refers to a pair. 'A-' means "not". Thus, "azygos" means "unpaired". The azygos vein is unpaired in that there is only one in the body, mostly on the right side. While there is the hemiazygos vein and its accessory on the left side of the body, they are considered tributaries of the azygos vein rather than its left-side equivalent.


=Additional

ee also

* Hemiazygos vein
* Posterior intercostal veins
* Superior vena cava

External links

* - "Right side of the mediastinum."
* [http://www.lumen.lumc.edu/lumen/MedEd/GrossAnatomy/dissector/labs/thorax/post_med/pm1_1a.htm Dissection at lumc.edu]
* [http://anatomy.med.umich.edu/radiology/xray/abdomen_cross_1.html Radiology at umich.edu]


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Look at other dictionaries:

  • azygos vein — n any of a system of three veins which drain the thoracic wall and much of the abdominal wall and which form a collateral circulation when either the inferior or superior vena cava is obstructed esp a vein that receives blood from the right half… …   Medical dictionary

  • azygos vein — noun one of a system of veins that drain the thoracic and abdominal walls; arises as a continuation of the right ascending lumbar vein and terminates in the superior vena cava • Syn: ↑azygous vein, ↑vena azygos • Hypernyms: ↑vein, ↑vena, ↑venous… …   Useful english dictionary

  • azygos vein — an unpaired vein that arises from the inferior vena cava and drains into the superior vena cava, returning blood from the thorax and abdominal cavities …   The new mediacal dictionary

  • lymph node of arch of azygos vein — nodus lymphoideus arcus venae azygos …   Medical dictionary

  • azygos — 1. An unpaired (azygous) anatomical structure. 2. SYN: a. vein. [G. a priv. + zygon, a yoke] a. continuation (of the inferior vena cava) a congenital anomaly in which the infrahepatic …   Medical dictionary

  • azygos lobe — lobe of azygos vein a small accessory or anomalous lobe at the apex of the right lung, produced when the azygos vein arches over the superior part of the lung and presses deeply into the lung tissue to form the azygos fissure …   Medical dictionary

  • Vein — In the circulatory system, a vein is a blood vessel that carries blood back toward the heart (as opposed to artery, a blood vessel carrying blood away from the heart). The majority of veins in the body carry low oxygen blood from the tissues back …   Wikipedia

  • Azygos — In anatomy, azygos, from the Greek άζυξ, refers to a structure that is unpaired. This is relatively unusual, as most elements of anatomy reflect bilateral symmetry. Another term for the same concept is impar.Well known structures incorporating… …   Wikipedia

  • azygos — I. noun Etymology: New Latin, from Greek, unyoked, from a + zygon yoke more at yoke Date: 1646 an azygos anatomical part II. adjective also azygous Date: 1681 not being one of a pair ; single < an azygos vein …   New Collegiate Dictionary

  • azygos fissure — an inconstant fissure at the apex of the right lung, produced when the azygos vein arches over the superior part of the lung instead of near the hilum; it sets off the azygos lobe …   Medical dictionary

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