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Anterior surface of Sternum and Costal Cartilages
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Posterior surface of sternum
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Sternum
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or '''breastbone''' is a long, flat
Bone located in the center of the
Thorax (chest). It connects to the
Rib Bones via
Cartilage , forming the
Rib Cage with them, and thus helps to protect the
Lungs and
Heart from physical
Trauma .
The sternum is sometimes cut open (a
Sternotomy ) to gain access to the thoracic contents when performing cardiothoracic surgery.
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. It consists of three parts, named from above downward:
In early life the body consists of four segments or ''sternebrœ.''
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.
The sternum is composed of highly vascular cancellous tissue, covered by a thin layer of compact bone which is thickest in the manubrium between the articular facets for the clavicles.
The sternum articulates on either side with the clavicle and upper seven
Costal Cartilages .
Fractures of the sternum are not common. However they may result from trauma, such as when a driver's chest is forced into the
Steering Column in an accident. A fracture of the sternum is usually a
Comminuted fracture, meaning it is broken into pieces. The most common site of sternal fractures is at the
Sternal Angle .
- ''Clinically Oriented Anatomy'', 4th ed. Keith L. Moore and Arthur F. Dalley. pp. 66-68.
