The xiphoid process is the smallest and most inferior segment of the sternum, or breastbone. This structure, which is often cartilaginous in younger individuals, is positioned in the center of the chest just above the abdomen. Its name derives from the Greek word for “sword-shaped,” reflecting its typically pointed or blade-like morphology.
Anatomical Positioning and Structure
The xiphoid process is situated at the bottom of the sternum, where the two sides of the ribcage meet. Anatomically, its tip aligns roughly with the level of the ninth or tenth thoracic vertebra (T9/T10). A person can generally locate it by tracing the sternum down to the bottom center of the chest, where the hard bone ends and the softer tissue of the upper abdomen begins.
The structure is highly variable in shape among different people, sometimes appearing pointed, rounded, or even split into a bifid shape. It may also have a natural perforation, or a small hole, in its center, known as a xiphoidal foramen. These structural variations are typically harmless, often inherited genetically, and represent normal differences in human anatomy. The xiphoid process connects to the body of the sternum via a fibrous joint called a synchondrosis.
Role in Musculoskeletal Attachment
The primary function of the xiphoid process is to act as an anchoring point for several muscles and connective tissues. It serves as an origin point for the abdominal diaphragm, the large, dome-shaped muscle beneath the lungs that drives respiration.
Muscles of the anterior abdominal wall also connect directly to the xiphoid process. Specifically, the rectus abdominis muscle inserts onto this structure. The xiphoid process also provides an attachment site for the aponeurosis of the internal and external oblique muscles. These attachments provide stability and leverage, making the xiphoid process integral to core body movement and trunk stability.
Age-Related Changes and Ossification
The composition of the xiphoid process changes significantly throughout life, explaining why it may feel soft or flexible in younger people. It is composed entirely of hyaline cartilage at birth. The process of ossification, where cartilage turns into bone, begins gradually as a person ages.
Full ossification of the xiphoid process is a slow process that often does not complete until late adulthood, commonly around or after the age of 40. Fusion of the xiphoid process to the body of the sternum through a fibrous joint typically occurs between the ages of 15 and 29.
Clinical Significance and Related Symptoms
The xiphoid process is an anatomical landmark used in certain medical procedures, such as locating the proper hand position for chest compressions during cardiopulmonary resuscitation (CPR). Care must be taken during CPR to ensure pressure is applied on the body of the sternum and not directly on the xiphoid process. Applying force to the xiphoid process can cause it to fracture or dislodge, potentially leading to injuries to underlying organs like the liver or diaphragm.
A condition known as xiphoidalgia, or xiphoid syndrome, causes pain and tenderness specifically in the area of the xiphoid process. This pain is often triggered by direct trauma to the chest, excessive coughing, or strenuous physical activities like heavy lifting that strain attached muscles. Symptoms may include localized pain or a feeling of tightness in the lower sternum, sometimes radiating to the upper abdomen, chest, or back. If a person experiences persistent pain, swelling, or difficulty breathing, consulting a healthcare provider is recommended to rule out other conditions.