Inferior thoracic aperture
The inferior thoracic aperture is irregular in shape and is more oblique and much larger than the superior thoracic aperture. The diaphragm occupies and closes the inferior thoracic aperture, thereby separating the thoracic and abdominal cavities. For structures to pass between the two cavities, they either pass behind the diaphragm or pass through various diaphragmatic apertures.
- posteriorly: 12 thoracic vertebral body and transverse processes
- posterolaterally: 11 and 12ribs
- anterolaterally: the costal margins formed by the conjoint costal cartilages of 7 to 10 ribs
- anteriorly: xiphisternal joint
Apart from the diaphragm, the list of structures that pass through the inferior thoracic outlet is best described by considering the various diaphragmatic apertures: