azygos vein

An unpaired vein which in humans arises from the right ascending lumbar vein or the vena cava, enters the thorax through the aortic orifice in the diaphragm, and terminates in the superior vena cava; unlike humans, mice have a single and left-sided azygos vein that develops from the paired embryonic cardinal venous system and drains most of the right and left thoracic walls into the left anterior vena cava[MP]. Every claim on this page comes from the Leumas anatomy graph and carries its source.

What the azygos vein is

An unpaired vein which in humans arises from the right ascending lumbar vein or the vena cava, enters the thorax through the aortic orifice in the diaphragm, and terminates in the superior vena cava; unlike humans, mice have a single and left-sided azygos vein that develops from the paired embryonic cardinal venous system and drains most of the right and left thoracic walls into the left anterior vena cava[MP]. The atlas records it as a vein at the organ scale in the human body.

Where the azygos vein is

It sits within the cardiovascular system. Positioned deliberately as part of this species body plan.

What the azygos vein connects to

The atlas records 12 typed relationships for it, across 4 kinds of connection. a kind of vein.

Supply and innervation

Venous drainage: accessory hemiazygos vein, esophageal vein, hemiazygos vein and right bronchial vein.

Also called

Also recorded as azygos venous tree and vena azygos. Searching any of those names reaches this page.

Source

Uberon multi-species anatomy ontology (Mungall et al.), CC BY 4.0. Term UBERON:0001594, version 2026-06-19, retrieved 2026-08-24. Licence: CC-BY-4.0.

• A kind of: vein.
• Connected to: anterior vena cava, posterior intercostal vein, right subcostal vein, right superior intercostal vein, superior intercostal vein and superior phrenic vein.
• drains to: accessory hemiazygos vein, esophageal vein, hemiazygos vein and right bronchial vein.
• contains: hemiazygos vein.

Questions

Where is the azygos vein?

It sits within the cardiovascular system. Positioned deliberately as part of this species body plan.

What does the azygos vein connect to?

A kind of: vein.

Is the azygos vein the same in other species?

Leumas holds the same relationship vocabulary for every species it carries, so where another dataset records this structure you can put the two side by side on /compare.