Accessory hemiazygos vein
Encyclopedia
The accessory hemiazygos vein (vena azygos minor superior) is a vein on the left side of the vertebral column
that generally drains the fifth through eighth intercostal spaces on the left side of the body.
.
It receives the posterior intercostal veins
from the 4th, 5th, 6th, and 7th intercostal spaces between the left superior intercostal vein
and highest tributary of the hemiazygos vein
; the left bronchial vein sometimes opens into it.
It either crosses the body of the eighth thoracic vertebra to join the azygos vein
or ends in the hemiazygos.
When this vein is small, or altogether absent, the left superior intercostal vein
may extend as low as the fifth or sixth intercostal space.
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
that generally drains the fifth through eighth intercostal spaces on the left side of the body.
Structure
The accessory hemiazygos vein varies inversely in size with the left superior intercostal veinSuperior intercostal vein
The superior intercostal veins are two veins that drain the 2nd, 3rd, and 4th intercostal spaces, one vein for each side of the body.-Right superior intercostal vein:...
.
It receives the posterior intercostal veins
Posterior intercostal veins
The posterior intercostal veins are veins that drain the intercostal spaces posteriorly. They run with their corresponding posterior intercostal artery on the underside of the rib, the vein superior to the artery. Each vein also gives off a dorsal branch that drains blood from the muscles of the...
from the 4th, 5th, 6th, and 7th intercostal spaces between the left superior intercostal vein
Superior intercostal vein
The superior intercostal veins are two veins that drain the 2nd, 3rd, and 4th intercostal spaces, one vein for each side of the body.-Right superior intercostal vein:...
and highest tributary of the hemiazygos vein
Hemiazygos vein
The hemiazygos vein is a vein running superiorly in the lower thoracic region, just to the left side of the vertebral column.-Structure:...
; the left bronchial vein sometimes opens into it.
It either crosses the body of the eighth thoracic vertebra to join the azygos vein
Azygos vein
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 right atrium by allowing the blood to flow between the venae cavae when one vena cava is blocked.-Structure:...
or ends in the hemiazygos.
When this vein is small, or altogether absent, the left superior intercostal vein
Superior intercostal vein
The superior intercostal veins are two veins that drain the 2nd, 3rd, and 4th intercostal spaces, one vein for each side of the body.-Right superior intercostal vein:...
may extend as low as the fifth or sixth intercostal space.