What is a xiphisternum?

The xiphisternum is the lowest and smallest part of the sternum, located at the bottom of the rib cage, specifically at the level of the tenth and eleventh vertebrae of the thoracic spine. It is also called the ensiform or xiphoid process. The xiphisternum is flexible cartilage in childhood, but it usually ossifies with age, becoming a bony structure in adults. Here are some further characteristics and functions of the xiphisternum:

1. Shape: The xiphisternum is typically sword-shaped, slightly longer than wide, and projects downward and forward from the body of the sternum.

2. Attachments: It serves as an attachment point for several muscles, including the diaphragm, rectus abdominis, and transversus abdominis. These muscles help in breathing, posture, and abdominal movements.

3. Costal Margin: Along with the sternum and costal cartilages, the xiphisternum forms the anterior boundary of the thoracic cage, helping to protect the heart, lungs, and other vital organs within the chest.

4. Variability: The size and shape of the xiphisternum can vary among individuals. In some cases, it may be more pointed, while in others, it may be shorter and broader.

5. Clinical Significance: The xiphisternum is sometimes used as an anatomical landmark for medical procedures. For instance, it may be used as a reference point during surgeries involving the upper abdomen or during resuscitation techniques such as cardiopulmonary resuscitation (CPR) where chest compressions are administered.

In summary, the xiphisternum refers to the lowermost part of the sternum, providing structural support and muscle attachments in the thoracic region of the body.