<P> The sternal angle (also known as the angle of Louis or manubriosternal junction) is the synarthrotic joint formed by the articulation of the manubrium and the body of the sternum . </P> <P> The sternal angle is a palpable clinical landmark in surface anatomy . </P> <P> The sternal angle, which varies around 162 degrees in males, marks the approximate level of the 2nd pair of costal cartilages, which attach to the second ribs, and the level of the intervertebral disc between T4 and T5 . In clinical applications, the sternal angle can be palpated at the T4 vertebral level . </P> <P> The sternal angle is used in the definition of the thoracic plane . This marks the level of a number of other anatomical structures: </P>

Which pair of ribs articulates with the sternum at the sternal angle