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| == Description == | | == Description == |
| The sternum (Colored part of figure shown below) is a Sword like flat bone that forms the thoracic skeleton's anterior median section. (BD CHAURASIA:BD_Chaurasia’s_Human_Anatomy, Volume 1 - Upper Limb Thorax, 6th Edition.pdf (archive.org))
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| Length of the bone: 17 cm {Size of sternum in males is longer than in females}
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| [[File:Sternum composition.png|center|thumb|150x150px|Figure: Sternum]]
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| === Structure === | | === Structure === |
| The sternum has 3 anatomical parts:
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| # Manubrium
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| # Body of the sternum
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| # Xiphoid process
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| '''1) Manubrium:'''
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| * Quadrilateral in shape.
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| * Thickest and Strongest part
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| * Surfaces:
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| ** Anterior surface:Convex from side to side; concave from above downwards.
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| ** Posterior Surface:Concave; it forms the anterior boundary of the superior mediastrernum.
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| * Borders:
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| ** Superior border: Thick,rounded and concave
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| *** marked by the suprasternalnotch or jugular notch or interclavicular notch in the median part
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| *** The clavicular notch on each side
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| ** Inferior border: It forms the secondary cartilaginous joint with the body of the sternum.
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| *** The manubrium makes a slight angle with the body, convex forwards, called the sternal angle of Louis.
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| ** Two lateral borders: It forms the primary cartilaginous joint with the first costal cartilage.
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| 2) '''Body of the sternum''':
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| * The body of the sternum is longer, narrower and thinner than the manubrium
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| * It is the widest close to its lower end opposite the articulation with the fifth costal cartilage.
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| * Surfaces:
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| ** Anterior surface: It is flat, directed forward and slightly upwards.
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| ** Posterior surface: slightly concave.
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| ** 2 lateral borders, upper end and lower end.
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| 3) '''Xiphoid process:'''
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| * The smallest part of the sternum
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| * It is at first cartilaginous, but later in the adult, it becomes ossified near its upper end.
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| * It varies in shape: It May be bifid or perforated.
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| * Surfaces:
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| ** Anterior surface
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| ** Posterior surface
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| ** Lateral border
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| == Function == | | == Function == |
