Accessory hemiazygos vein

Dr Daniel J Bell ◉ and Dr Henry Knipe ◉ ◈ et al.

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.

On this page:

Article:

Terminology
Gross anatomy
Variant anatomy
Related articles
References

Images:

Cases and figures

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 4^th-8^th 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

References

Anatomy: Thoracic

Anatomy: Thoracic

thoracic skeleton
- thoracic cage
  - ribs
    - typical ribs
    - atypical ribs
    - variant anatomy
  - costal cartilage
  - sternum
- thoracic spine
- articulations
muscles of the thorax
spaces of the thorax
thoracic viscera
- tracheobronchial tree
  - trachea
- lungs
- heart
  - cardiac chambers
  - heart valves
  - pectinate muscles
  - cardiac fibrous skeleton
    - aortic annulus
  - coronary arteries
    - coronary arterial dominance
    - myocardial segments
    - left main coronary artery (LMCA)
      - ramus intermedius artery (RI)
      - circumflex artery (LCx)
        
        obtuse marginal branches (OM1, OM2, etc))
        
        Kugel's artery
      - left anterior descending artery (LAD)
        
        diagonal branches (D1, D2, etc)
        
        septal perforators (S1, S2, etc)
    - right coronary artery (RCA)
      - conus artery
      - sinoatrial nodal artery
      - acute marginal branches (AM1, AM2, etc)
      - inferior interventricular artery (PDA)
      - posterior left ventricular artery (PLV)
    - congenital anomalies
  - innervation of the heart
  - fetal circulation
    - foramen ovale
  - atrial septum
    - fossa ovale
  - endocardium
  - myocardium
  - pericardium
    - epicardium
    - epicardial fat pad
    - pericardial space
      - oblique pericardial sinus
      - transverse pericardial sinus
      - pericardial recesses
        
        aortic recesses
        
        superior aortic recess
        
        inferior aortic recess
        
        pulmonic recesses
        
        right pulmonic recess
        
        left pulmonic recess
        
        postcaval recess
        
        pulmonary venous recesses
        
        right pulmonary venous recess
        
        left pulmonary venous recess
    - pericardial ligaments
- esophagus
  - Zenker diverticulum
  - Killian-Jamieson diverticulum
- thymus
  - retrocaval thymus
- breast
  - nipple-areola complex
  - terminal ductal lobular unit
  - axillary tail
    - foramen of Langer
  - mammary fat
  - Montgomery glands
    - Montgomery tubercles
  - Cooper ligaments
    - crests of Duret
  - retromammary space (Chassaignac bursa)
  - lymphatic drainage
    - Sappey plexus
    - intramammary lymph nodes
  - variants
    - supranumerary nipple (polythelia)
    - accessory breast tissue (polymastia)
    - breast hypoplasia
    - amastia
    - amazia
blood supply of the thorax
- arteries
  - thoracic aorta (development)
  - pulmonary trunk
    - left pulmonary artery
      - aberrant left pulmonary artery
    - right pulmonary artery
- veins
  - superior vena cava (SVC)
    - superior cavoatrial junction
    - variant anatomy
  - inferior vena cava (IVC)
    - inferior cavoatrial junction
  - coronary veins
    - cardiac veins which drain into the coronary sinus
      - great cardiac vein
      - middle cardiac vein
      - small cardiac vein
      - posterior vein of the left ventricle
      - vein of Marshall (oblique vein of the left atrium)
    - anterior cardiac veins
    - venae cordis minimae (smallest cardiac veins or thebesian veins)
  - pulmonary veins
    - bronchial veins
  - thoracoepigastric vein
lymphatics
innervation of the thorax

Article information

rID: 26595

System: Chest, Vascular

Section: Anatomy

Synonyms or Alternate Spellings:

Superior hemiazygos vein

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Cases and figures

Figure 1 Figure 1

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Case 1: appearance on CTPACase 1: appearance on CTPA

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