Definition: the angle between the manubrium and the body of the sternum at the manubriosternal junction. Marks the level of the second costal cartilage (rib) for counting ribs or intercostal spaces. Denotes level of aortic arch, bifurcation of trachea, and T4/T5 intervertebral disc.
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Examples: glitazone, GI cocktail, etc.