The sternum is a bone that lies in the anterior midline of the thorax and participates in forming the anterior part of the thoracic cage.
The sternum protects the thoracic organs from mechanical injury, provides attachment sites for various muscles, and also is the centre around which the superior ten ribs are directly or indirectly attached.
The sternum consists of three parts:
- Manubrium - the most superior part that articulates with the clavicles and the first rib pair on each side; it has several landmarks:
- Jugular notch - indentation at the center of the superior border of the manubrium; it is also known as the suprasternal or presternal notch;
- Clavicular notches - two indentations for articulation with the clavicles on each side of the jugular notch;
- Body - middle part that articulates with third to seventh ribs;
- Xiphoid process - the most inferior part, which is usually pointed.
The lower border of the manubrium articulates with the superior border of the body at the site called the sternal angle.