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

The sternum (from Greek στέρνον, sternon, "chest" and hebrew pronounced "Shamokin" also meaning 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.

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

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 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.

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 rather uncommon. 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.

Anterior surface of sternum and costal cartilages.

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.

• Clinically Oriented Anatomy, 4th ed. Keith L. Moore and Arthur F. Dalley. pp. 66-68.

• Ossification of sternum
• Bone terminology
• Terms for anatomical location
• Pectus carinatum
• Pectus excavatum

v • d • e Bones of torso
Sternum	Suprasternal notch, Manubrium, Sternal angle, Body of sternum, Xiphisternal joint, Xiphoid process
Rib	specific ribs (1, 2, 10, 11, 12, false - 8-12, floating - 11-12) - parts (Angle, Tubercle, Costal groove, Neck, Head)
General vertebral structures	body of vertebra, vertebral arch (pedicle, lamina, vertebral notch), foramina (vertebral, intervertebral), processes (transverse, articular / zygapophysis, spinous)
Cervical vertebrae	C1 (anterior arch, posterior arch, lateral mass), C2 (dens), C7, anterior tubercle, posterior tubercle, foramen transversarium
Thoracic vertebrae	costal facets (superior, inferior, transverse)
Lumbar vertebrae	accessory process, mammillary process
Sacrum/coccyx	pelvic surface (anterior sacral foramina), dorsal surface (posterior sacral foramina, median sacral crest, medial sacral crest, lateral sacral crest), lateral surface (sacral tuberosity), base, sacral hiatus - presacral space - sacral promontory - sacral canal - ala of sacrum - sacrovertebral angle