Vessel
Accessory hemiazygos vein
A variable collector of left mid-thoracic intercostal veins
High-yield
Accessory hemiazygos and hemiazygos usually collect different levels of the left posterior chest wall, but their boundaries and connections vary.
Overview
The accessory hemiazygos channel descends on the left side of the upper-to-middle thoracic vertebrae. It gathers several posterior intercostal veins and commonly crosses into the azygos system. Connections with the hemiazygos and left superior intercostal veins differ between people.
Reference facts
- Origin
- Several left posterior intercostal veins in the upper-to-middle thorax
- Course
- Descends along the left side of the vertebral bodies and commonly crosses posterior to central mediastinal structures near T7–T8
- Branches
- Middle left posterior intercostal tributaries, with variable communicating veins
- Supplies
- Drains part of the left posterior thoracic wall
- Drains to
- Azygos or hemiazygos pathways; communication with the left superior intercostal vein may occur
Clinical correlation
An enlarged or unusually positioned accessory channel can resemble another mediastinal structure on imaging. Its venous continuity helps distinguish a variant from a mass.
Frequently asked questions
Where does the accessory hemiazygos vein originate?
The accessory hemiazygos vein arises from the several left posterior intercostal veins in the upper-to-middle thorax.
What territory does the accessory hemiazygos vein serve?
Drains part of the left posterior thoracic wall.
Where does the accessory hemiazygos vein drain to?
Azygos or hemiazygos pathways; communication with the left superior intercostal vein may occur.
What are the branches of the accessory hemiazygos vein?
Branches of the accessory hemiazygos vein include the middle left posterior intercostal tributaries, with variable communicating veins.