  the xiphoid process , or xiphosternum or metasternum, is a small cartilaginous process (extension) of the lower part of the sternum which is usually ossified in the adult human. ==structure== the xiphoid process is considered to be at the level of the 9th thoracic vertebra and the t6 dermatome. ===development=== in newborn babies and young (especially slender) infants, the tip of the xiphoid process may be both seen and felt as a lump just below the sternal notch. by age 15 to 29, the xiphoid usually fuses to the body of the sternum with a fibrous joint. unlike the synovial articulation of major joints, this is non-movable. ossification of the xiphoid process occurs around age 40. ===variation=== the xiphoid process can be naturally bifurcated, and sometimes perforated. these variances in morphology are inheritable, which can help group family members together when dealing with burial remains. these morphological differences pose no health risk, and are simply a difference in form. ===in animals=== in birds, the xiphoid process is a long structure, often following the direction of the carina. ==function== much the way the first seven ribs articulate with the sternum, the cartilage in the celiac plexus joins on the xiphoid process, reinforcing it, and indirectly attaches the costal cartilage to the sternum. ==clinical significances== pressure on the xiphoid process should be avoided when administering chest compressions in cpr, as this can cause the xiphoid process to break off, resulting in punctures or lacerations of the diaphragm. additionally, the liver may be punctured, resulting in lethal hemorrhaging. xiphoidalgia (xiphodynia) is a syndrome distinguishable by pain and tenderness to the sternum. while some sources describe this disorder as rare, others suggest it is relatively common but overlooked by physicians. symptoms can include abdominal pain, chest pain, nausea and radiating pain to the back, neck, and shoulders. lifting heavy objects or trauma to the chest may be the cause of this musculoskeletal disorder and pain may be heightened by bending or twisting. anesthetic and steroid injections are common
Bones_of_the_thorax