The xiphisternum (also known as the xiphoid process or simply the xiphoid) is the smallest of the three parts of the sternum (manubrium, body or gladiolus, and xiphisternum). It arises from the inferior and posterior margin of the sternal body and projects inferiorly. It is a small cartilaginous extension of the lower sternal body, with which it forms an articulation. It usually ossifies later in life.
The xiphoid is thin and elongated, but its morphology can be quite varied, including being bifid, perforated, broad, curved or deflected to one side . This variability is genetic and thus can be used for identification of relatives, but otherwise is without clinical significance. The xiphoid can form a reference point for performing chest compressions in CPR (cardiopulmonary resuscitation) and is found at the level of the ninth thoracic vertebra .
The xiphisternum forms a symphysis with the lower end of the sternal body, the so-called xiphisternal joint. This process can ossify at any time after the third year of life but usually occurs in adulthood after the fourth decade .
- rectus abdominis muscle and the linea alba: the aponeurosis of the abdominal muscles extends from the xiphisternum to the pubic symphysis
- diaphragm: the xiphisternum forms part of the attachment of the diaphragm to the anterior chest wall
- costoxiphoid ligaments: these variable fibrous bands form connections between the xiphisternum and the 7th, and sometimes the 6th costal cartilages
History and etymology
Derived from the Ancient Greek xiphoeides (ξιφοιδης) 'sword-shaped', from xiphos (ξιφος) ‘sword’ and 'eidos (ειδος) 'resembling' .