Aortic isthmus

Dr Rohit Sharma ◉ and Dr Jeremy Jones ◉ et al.

The aortic isthmus is the part of the aorta just distal to the origin of the left subclavian artery at the site of the ductus arteriosus.

This portion of the aorta is partly constricted in the fetus because of the lack of flow within the aortic sac and ascending aorta. It marks the partial separation of fetal blood flow derived from the right and left ventricles.

History and etymology

Derived from the Ancient Greek ισθμος (isthmos) meaning a neck of land ³.

Related pathology

most common anatomical area of traumatic thoracic aortic injuries in patients surviving long enough to be imaged ¹
the site of the ductus diverticulum which is an anatomical variant of the aorta that should be differentiated from an aortic pseudoaneurysm in the setting of trauma ²
the aortic isthmus index (isthmus flow index) is used in obstetric Doppler as a marker of raised placental resistance and fetal growth restriction ⁴

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: 22291

System: Cardiac, Vascular, Trauma

Section: Anatomy

Tag: refs, refs, anatomy-illustrations, artery

Synonyms or Alternate Spellings:

Isthmus of the aorta
Aortic isthmi

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Cases and figures

Figure 1: thoracic aortaFigure 1: thoracic aorta

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