[lee-usmle]

One of the commonest anatomy questions in USMLE Step 1 is relations to the sternal angle.

Whenever, you see the sternal angle in a question this should immediately bring the following to your mind:

• Level of second rib, second costal cartilage. Therefore, we use it as a landmark to count the ribs and intercostal spaces clinically.
• It's cross sectional will go posteriorly to meet the T4/T5 Intervertebral Disc.
• It marks the entry and exit of the aortic arch to and from the superior mediastinum.
• It marks the bifurcation of the trachea.
• It is the landmark by which we divide the mediastinum into superior and inferior divisions.
• Azygous vein entry into the superior vena cava.
• Fusion of the right and left mediastinal pleurae in the midline anteriorly.

Have you got more clues, post your reply and I'll add them ...