Sternum:
This article is about vertebrate anatomy. For the arthropod anatomical structure, see Sternum (arthropod). 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.
[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 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).
[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
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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. However, some studies reveal that repeated punches or continual beatings, sometimes called "sternum punches", to the sternum area have also caused fractured sternums. Sternum fractures are frequently associated with underlying injuries such as pulmonary contusions, or bruised lung tissue.[1]
[edit] Additional images
[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.
- Clinically Oriented Anatomy, 4th ed. Keith L. Moore and Arthur F. Dalley. pp. 66-68.
[edit] See also
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Bones of torso |
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| Rib |
specific ribs ( 1, 2, 9, 10, 11, 12, false – 8–12, floating – 11–12) – parts ( Angle, Tubercle, Costal groove, Neck, Head)
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| Vertebra |
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General structures
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C1 ( anterior arch, posterior arch, lateral mass), C2 ( dens), C3, C4, C5, C6, C7
anterior tubercle, posterior tubercle, foramen transversarium
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T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12
costal facets ( superior, inferior, transverse)
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