Xi / 22A18 / 16A16: Outline the anatomy of the subclavian vein relevant to central venous line insertion

22A18: Exam Report

Describe the anatomy of the left subclavian vein

14% of candidates passed this question.

An ideal answer includes origin of subclavian vein, its tributaries, course in relation to mediastinal structures and surface anatomy for central line insertion.

Vague comments like: “it follows the subclavian artery”, or “it passes between 1st rib and clavicle”, attract minimal marks. Similarly, no marks were awarded for describing technique of central line insertion and complications of procedure.

Answers scored poorly due to a combination of the following, a lack of depth to their answers or inaccurate facts and limited structure/approach to an anatomical SAQ.

Good answers described the course of the subclavian vein from its origin at the lateral border of the first rib, along the subclavian groove on the upper surface of the first rib, medially to its termination posterior to the sternoclavicular joint at the medial border of the scalenus anterior, where it joined the IJV to form the bracheoceaphalic vein.

In addition, high scoring candidates described tributaries (e.g., the thoracic duct, external jugular) where they joined and went on to describe relations in reasonable detail, specifying whether patient is supine or erect.

16A16: Exam Report

Outline the anatomy of the subclavian vein relevant to central venous line insertion

38% of candidates passed this question.

Answers to anatomy questions can be generally structured by considered the origin and ending of the structure, the surface landmarks and the relations (medial / lateral / anterior / posterior) and this would have worked well in this question.

It was expected candidates could detail course (from origin to end) and relations of subclavian vein. This could then be used to highlight how these features may be relevant to central venous line insertion (proximity of subclavian artery or pleura creating the possibility of inadverant arterial puncture or pneumothorax.

Many candidates failed to mention drainage of external jugular vein and thoracic duct and right lymphatic ducts into the subclavian veins. Candidates should ensure
diagrams are accurate and well labelled and they use appropriate anatomical terminology rather than vague terms such as “in front”.

Care should be taken ensuring accuracy (e.g. some mentioned dome of diaphragm instead of pleura or IVC instead of SVC).

Xi / 22A18 / 16A16: Outline the anatomy of the subclavian vein relevant to central venous line insertion


  • Continuation of axillary vein as it crosses upper surface of first rib
  • Joins with internal jugular vein to form brachiocephalic vein at sternoclavicular junction → enters SVC


  • Travels posterior to clavicle, separated from subclavian artery by anterior scalene
  • Travels over superior surface of first rib forming slight groove


  • Anterior: Clavicle, subclavius muscle, pectoralis major
  • Posterior: Anterior scalene muscle, subclavian artery
  • Inferior: First rib & lung apex, first intercostal space
  • Superior: Skin, subcutaneous tissue, platysma
  • Medial: Brachiocephalic vein, thoracic duct, trachea, vagal trunks
  • Lateral: Axillary vein, inferior trunk of brachial plexus


  • Subclavian arteryis posterior-superior to companion vein → separated by anterior scalene muscle
  • Right lymphatic duct drains lymph into junction of R IJV and R subclavian
  • Thoracic duct drains into L subclavian near junction of L IJV
  • External jugular vein drains into subclavian vein lateral/anterior to anterior scalene


  • Axillary vein
  • External jugular vein
  • Dorsal scapular vein
  • Anterior jugular veins

Surface Anatomy

  • Needle placed in deltopectoral groove, inferior & lateral to middle 3rd of clavicle
  • Insert needle at shallow angle, passing under middle 3rd of clavicle aiming at sternal notch


  • Supraclavicular
  • Infraclavicular
  • Lateral


  • Trendelenburg position: flat with 20° head down tilt → helps to avoid air embolus (no ↑ in diameter)
  • Folded towel between scapulae to retract shoulder & enlarge procedural field

Author: Novia Tan