Body of Sternum

The body of the sternum, also known as the gladiolus, is the long, flat central part of the sternum. It serves as the primary anterior support structure for the thoracic cage and provides articulation points for several ribs. Along with the manubrium and xiphoid process, it forms the sternum, protecting underlying organs and supporting respiratory movements.

Location

The body of the sternum lies in the midline of the anterior thoracic wall, inferior to the manubrium and superior to the xiphoid process. It extends from the level of the second to the seventh costal cartilages, approximately spanning vertebral levels T5 to T9.

Structure

The sternal body is roughly rectangular and longer than the manubrium and xiphoid process. It is composed of compact outer cortical bone and internal cancellous bone. During development, it consists of four sternebrae that fuse by adulthood.

Key Features

• Costal notches: Located along its lateral borders; provide articulation points for the 2nd to 7th costal cartilages
• Transverse ridges: Indicate fusion lines of sternebrae in adults
• Manubriosternal joint (superior): Forms the sternal angle (Angle of Louis) with the manubrium
• Xiphisternal joint (inferior): Junction with the xiphoid process; marks the inferior limit of the sternum

Articulations

• Manubrium: Forms the manubriosternal joint (symphysis type)
• Xiphoid process: Forms the xiphisternal joint (symphysis or synostosis in older adults)
• Costal cartilages of ribs 2 to 7: Via sternocostal joints

Muscle Attachments

• Pectoralis major: Attaches to the anterior surface of the sternal body
• Transversus thoracis: Arises from the posterior surface of the lower sternum
• Rectus abdominis: Indirectly connects through the anterior abdominal wall and costal cartilages

Function

• Forms the central anterior part of the thoracic cage
• Provides support and articulation for ribs 2–7
• Protects mediastinal organs including heart, great vessels, and lungs
• Serves as a strong anchor for thoracic and upper abdominal muscles

Blood Supply

• Arterial supply: Internal thoracic arteries and anterior intercostal branches
• Venous drainage: Internal thoracic veins into the brachiocephalic vein

Innervation

• Cutaneous sensation overlying the sternum is provided by anterior cutaneous branches of thoracic intercostal nerves (T2–T6)

Clinical Relevance

• Sternal angle (Angle of Louis): Marks the level of the second rib, arch of aorta, and tracheal bifurcation (T4–T5)
• Sternal fractures: Can occur due to direct trauma; may be associated with injury to mediastinal structures
• Median sternotomy: Common surgical approach for cardiac and thoracic surgeries; involves splitting the sternal body
• Bone marrow aspiration: While less common than other sites, sternal puncture may be performed on the sternal body