Anterior Thoracic Surface

Practice on yourself:

If you run your finger down the anterior midline of your neck, you will feel the cartilaginous rings reinforcing the trachea until it disappears behind the sternum. You should now feel the suprasternal notch on the superior margin of the sternum. If you move your fingers laterally from the notch, you will feel the heads of the clavicles on each side as they articulate with the upper part of the sternum.

The first rib lies deep to the clavicle and consequently, is difficult to palpate. It is more practical, therefore, to start rib counting from the second rib. If you return your finger to the midline of the suprasternal notch and run it vertically downwards in the midline, you will encounter the sternal angle, a ridge made by the joint between the manubrium and the body of the sternum about 2.5 cm below the sternal notch.

If you now slide your finer laterally, it will pass on to the skin over the second rib and its associated costal cartilage. The second intercostal space is below the second rib and costal cartilage. Once the level of the second rib is established, it is simple to countdown the successive ribs and intercostal spaces.

Return to the midline and continue tracing the sternum down. At the lower border of the sternum, you may be able to feel its short sharp downward process, the xiphoid process. Once you get to this level, you will have to move your hands laterally to be able to feel the lower ribs and intercostal spaces. The costal margin, the lower margin of the thoracic cage, curves downwards and laterally. The costal margin is formed by the costal cartilages of the seventh, eighth, ninth, and tenth ribs. There are usually 12 pairs of ribs in all, but you will probably not be able to feel the eleventh and twelfth rib.

For example: A horizontal line from the sternal angle intersects the interveretebral disc between the fourth and fifth thoracic vertebrae (T4/T5). This is the sternal plane and is an important landmark. The sternal notch is on the same level as T2 and the xiphoid process on the same level as T9.