Definition

1. Noun:
   • A single vein draining the thoracic and abdominal walls: The azygous vein is an unpaired blood vessel that collects blood from the walls of the chest and abdomen. It begins as an extension of the right ascending lumbar vein and ends by connecting to the superior vena cava, a major vein returning blood to the heart.

Usage

• The term is used specifically in anatomical and medical contexts to describe this particular venous structure.
• It is often discussed in relation to the venous drainage of the posterior thoracic wall.

Examples

• Noun:
  • The surgeon carefully avoided the azygous vein during the procedure.
  • An enlarged azygous vein can sometimes be seen on a chest radiograph.

Advanced Usage

• "Azygos vein": This is a common alternate spelling for "azygous vein". Both terms refer to the same anatomical structure.
  • The azygos vein forms an important collateral pathway if the inferior vena cava is blocked.

Variants and Related Words

• Azygos vein (n): The standard anatomical term, synonymous with "azygous vein".
• Hemiazygos vein (n): A smaller, similar vein on the left side of the body, which often connects to the azygous/azygos vein.
• Accessory hemiazygos vein (n): Another vein on the left side, superior to the hemiazygos, also draining into the azygous/azygos system.

Synonyms

• Azygos vein: The direct synonym, with "azygos" being the more frequently used form in technical literature.

Notes on Meaning

• The word "azygous" (or "azygos") comes from Greek, meaning "unpaired" or "not yoked," which accurately describes this single, midline vein compared to the typically paired veins in the body.
• Its primary function is to provide a pathway for blood to return to the heart from the posterior walls of the thorax and abdomen.

Noun

1. 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