Costal Process

The costal processes are the upper anterior ends of the eight ribs and their arcuate or jagged border (line of percussion). In the lower third of the sternum they end in a flat, pointed protrusion - the costal tubercle. All 8 ribs are connected to the sternum through a ring of muscles - the xiphoid cartilage, located between the fourth and fifth sternal openings.

The costal bones participate in the formation of the lateral border of the body and limit the thoracic cavity from the chest. Under each costal process, connecting it with the costal arch (more precisely, its lower edge), an intrathoracic vein passes (its direction once again emphasizes the location of the horizontal diameter of the chest at the level of the ribs). Medial to the latter is the serratus anterior muscle, lateral to the external intercostal muscle. The last two muscles begin on the costal processes and, rising, are attached to the posterior edge of the scapula, above the shoulder joint. The ribs perform a protective function, covering the heart muscle, lungs, large vessels and nerve trunks, as well as the abdominal organs. In their structure, they are a continuation of the flat bones of the skull and also have a spongy structure. This is explained by the fact that the ribs that protect soft tissues and organs must be strong (especially the lower ones), but at the same time light (the upper ribs bear almost no load in people without physical labor). The anterior costal angles are quite sharp (developed for better attachment of muscles that provide sideways movements of the body), the posterior ones are almost flat, vertical (attached to the transverse processes of the vertebrae, forming a deep