thoracic inlet (anatomy)

Last reviewed 01/2018

The thoracic inlet is the most superior aperture to the thorax and the boundary of the roof of the mediastinum. Also, it is termed the:

  • superior thoracic aperture; another anatomical term
  • thoracic outlet; clinical usage e.g. thoracic outlet syndrome. However, it is not the anatomical thoracic outlet - see submenu.

The thoracic inlet slopes obliquely anteriorly and inferiorly from the first vertebral body. Its anteroposterior diameter is 4.5-6cm. Its transverse diameter is 9-11cm.

The thoracic inlet can be described in terms of:

  • its bony margins
  • the relations of structures traversing the area