What is the Sternum
The sternum (from Greek ,sternon, “chest” or breastbone) is a long flat bone (or, in some models, set of three bones) shaped like a capital ‘T’ located in the center of the thorax (chest). It connects to the rib bones via cartilage, forming the anterior section of the rib cage with them, and thus helps to protect the lungs, heart and major blood vessels from physical trauma.
The sternum is sometimes cut open (a median sternotomy) to gain access to the thoracic contents when performing cardiothoracic surgery.
Structure
The sternum is composed of highly vascular tissue, covered by a thin layer of compact bone which is thickest in the manubrium between the articular facets for the clavicles.
The sternum is an elongated, flattened bone, forming the middle portion of the anterior wall of the thorax. Its upper end supports the clavicles (Collar bones), and its margins articulate with the cartilages of the first seven pairs of ribs. Its top is also connected to the Sternocleidomastoid muscle. It consists of three parts, from above downward:
- Manubrium
- Body of sternum (gladiolus)
- Xiphoid process
In its natural position, the inclination of the bone is oblique from above, downward and forward. It is slightly convex in front and concave behind; broad above, becoming narrowed at the point where the manubrium joins the body, after which it again widens a little to below the middle of the body, and then narrows to its lower extremity. Its average length in the adult is about 17 cm, and is rather longer in the male than in the female.
In early life its body is divided in three segments, called sternebrœ (singular: sternebra).
Structure
The sternum is composed of highly vascular tissue, covered by a thin layer of compact bone which is thickest in the manubrium between the articular facets for the clavicles.
