Accessory hemiazygos vein
The accessory (or superior) hemiazygos vein forms part of the azygos system and along with the hemiazygos vein, it is partially analogous to the right-sided azygos vein. It drains the left superior hemithorax.
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Terminology
Spelling it "hemiazygous" when referring to the vein is incorrect, regardless of whether British or American English 5. In the context of anatomy, see Terminologia Anatomica, hemiazygos vein is the sole correct spelling.
Gross anatomy
Origin and course
The accessory hemiazygos vein is formed by the confluence of the middle left posterior intercostal veins. It descends to the left of midline, adjacent to the thoracic vertebrae and crosses posteriorly to the aorta at the level of T7-8 to drain into the azygos vein. It normally anastomoses with the left superior intercostal vein.
Tributaries
- left 4th-8th posterior intercostal veins
- left bronchial veins (variable)
Variant anatomy
- drains via a common trunk with the hemiazygos vein into the azygos vein
- forms a common trunk with the hemiazygos vein that passes anterior to the aorta called the interazygos vein 2
- drains directly into the left brachiocephalic vein (rare) 2
Related Radiopaedia articles
Anatomy: Thoracic
- thoracic skeleton
- thoracic cage
- thoracic spine
- articulations
- muscles of the thorax
- diaphragm
- intercostal space
- intercostal muscles
- variant anatomy
- spaces of the thorax
- thoracic viscera
- tracheobronchial tree
-
lungs
-
bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)
- left lung
- right lung
- variant anatomy
- lung parenchyma
- hilum
- pleura
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bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)
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heart
- cardiac chambers
- heart valves
- pectinate muscles
- cardiac fibrous skeleton
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coronary arteries
- coronary arterial dominance
- myocardial segments
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left main coronary artery (LMCA)
- ramus intermedius artery (RI)
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circumflex artery (LCx)
- obtuse marginal branches (OM1, OM2, etc))
- Kugel's artery
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left anterior descending artery (LAD)
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right coronary artery (RCA)
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- endocardium
- myocardium
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pericardium
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- epicardial fat pad
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pericardial recesses
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coronary veins
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- great cardiac vein
- middle cardiac vein
- small cardiac vein
- posterior vein of the left ventricle
- vein of Marshall (oblique vein of the left atrium)
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- cardiac veins which drain into the coronary sinus
- pulmonary veins
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