Sternum

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This article is about vertebrate anatomy. For the arthropod anatomical structure, see Sternum (arthropod).

Bone: Sternum

Anterior surface of sternum and costal cartilages.

Posterior surface of sternum.
Gray's	subject #27 119
MeSH	Sternum
Dorlands/Elsevier	s_23/12758288

The sternum (from Greek στέρνον, sternon, "chest") 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, 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.

1 Overview
2 Structure
3 Articulations
4 Fractures of the sternum
5 Additional images
6 References
7 See also

[edit] Overview

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:

In early life, the body of sternum 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.

[edit] Structure

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.

[edit] Articulations

The sternum articulates on either side with the clavicle and upper seven costal cartilages.

[edit] Fractures of the sternum

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 of a car in a car 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.

[edit] Additional images

Thoracic cage

[edit] References

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.