Costal Notches Of The Sternum, Lateral View

Description

Sternum costal notches line the lateral border of the manubrium and sternal body, forming the reception sites for the costal cartilages of ribs 1 through 7 in the anterior thorax. From this lateral perspective, the manubrium sits superior to the sternal body, with the xiphoid process tapering inferiorly, while the notches appear as stepwise concavities along the anterior margin of the sternum’s lateral edge. The 1st costal notch lies on the manubrium, the 2nd spans the manubriosternal junction at the sternal angle (Angle of Louis), and the remaining notches descend on the body toward the xiphisternal junction. Bony landmarks are unmistakable. These relationships matter any time you need to localize rib levels on the anterior chest wall. Clinicians count ribs by palpating the sternal angle to find the 2nd costal cartilage, then track inferiorly to guide chest tube placement, needle thoracostomy, or intercostal nerve block positioning while avoiding off-by-one errors. The lateral view also helps clarify why the 1st sternocostal joint is typically a synchondrosis, while ribs 2 to 7 form synovial sternocostal joints, a distinction that influences patterns of pain in costochondritis and the appearance of age-related costal cartilage calcification on CT or radiographs. Anatomy faculty can pair this illustration with lectures on thoracic wall osteology and surface anatomy, and authors can drop it into surgical texts discussing median sternotomy, sternal fracture lines, and parasternal approaches where costal cartilage relationships guide dissection. It also fits well in radiology primers that correlate the sternal angle with the T4 to T5 level and the transverse thoracic plane. Anatomical accuracy verified by SciePro's Medical Advisory Board.