[Plate 239, Cross Section of Thorax at T7 Level][Plate 532, Key Figures to Cross Sections]The thorax lies between the neck and the abdomen and lies within a cage formed by the vertebrae, the ribs, the sternum, the costal
cartilages, and their attached muscles. The thoracic cage protects the contents of the thorax, whereas the muscles assist in breathing.
It is important to identify and count ribs as they form key landmarks to the positions of the internal organs.
In a fit muscular person one can identify a number of landmarks:
Jugular (suprasternal) notch: at the level of the inferior border of the T2 vertebra
Sternal angle (manubriosternal join): at the level of the T4/5 intervertebral disc and where the second costal cartilages articulate with
the sternum.
Manubrium: The left brachiocephalic vein runs beneath the manubrium from the upper left to lower right, where it joins the right
brachiocephalic vein to form the superior vena cava