With POEM, knowing the landmarks outside of the oesophagus has become something which endoscopists are expected to be familiar with. Here is a quick self-test!
AT WHICH POSITION OF THE 'CLOCKFACE' DO YOU FIND THE:
■ Anterior vagal trunk
■ Posterior vagal trunk
■ Thoracic duct
■ Left lung
■ Azygous vein
4 o'clock - runs in the posterior mediastinum, on the right side of thoracic vertebral column. It drains into the SVC, and returns blood from the posterior walls of the thorax and the abdomen.