Body of sternum
Encyclopedia
The body of the sternum (gladiolus), considerably lengthier, narrower, and thinner than the manubrium
, attains its greatest breadth close to the lower end.
The posterior surface, slightly concave, is also marked by three transverse lines, less distinct, however, than those in front; from its lower part, on either side, the Transversus thoracis takes origin.
, the junction of the two forming the sternal angle
(angulus Ludovici).
The inferior border is narrow, and articulates with the xiphoid process
.
Each lateral border, at its superior angle, has a small facet, which with a similar facet on the manubrium, forms a cavity for the cartilage of the second rib; below this are four angular depressions which receive the cartilages of the third, fourth, fifth, and sixth ribs, while the inferior angle has a small facet, which, with a corresponding one on the xiphoid process, forms a notch for the cartilage of the seventh rib. These articular depressions are separated by a series of curved interarticular intervals, which diminish in length from above downward, and correspond to the intercostal spaces. Most of the cartilages belonging to the true ribs, as will be seen from the foregoing description, articulate with the sternum at the lines of junction of its primitive component segments. This is well seen in many of the lower animals, where the parts of the bone remain ununited longer than in man.
Manubrium
The manubrium or manubrium sterni is the broad, upper part of the sternum. Located ventrally with a quadrangular shape, wider superiorly and narrower inferiorly, it articulates with the clavicles and the first two ribs.-Borders:The superior border is the thickest and presents at its center the...
, attains its greatest breadth close to the lower end.
Surfaces
Its anterior surface is nearly flat, directed upward and forward, and marked by three transverse ridges which cross the bone opposite the third, fourth, and fifth articular depressions. It affords attachment on either side to the sternal origin of the Pectoralis major. At the junction of the third and fourth pieces of the body is occasionally seen an orifice, the sternal foramen, of varying size and form.The posterior surface, slightly concave, is also marked by three transverse lines, less distinct, however, than those in front; from its lower part, on either side, the Transversus thoracis takes origin.
Borders
The superior border is oval and articulates with the manubriumManubrium
The manubrium or manubrium sterni is the broad, upper part of the sternum. Located ventrally with a quadrangular shape, wider superiorly and narrower inferiorly, it articulates with the clavicles and the first two ribs.-Borders:The superior border is the thickest and presents at its center the...
, the junction of the two forming the sternal angle
Sternal angle
The sternal angle or 'angle of Louis', from the Latin angulus Ludovici is the anterior angle formed by the junction of the manubrium and the body of the sternum in the form of a secondary cartilaginous joint . This is also called the manubriosternal joint or Angle of Louis...
(angulus Ludovici).
The inferior border is narrow, and articulates with the xiphoid process
Xiphoid process
The xiphoid process, or xiphisternum or metasternum, is a small cartilaginous process of the lower part of the sternum which is usually ossified in the adult human. By age 15 to 29, the xiphoid usually fuses to the body of the sternum with a fibrous joint. Unlike the synovial articulation of major...
.
Each lateral border, at its superior angle, has a small facet, which with a similar facet on the manubrium, forms a cavity for the cartilage of the second rib; below this are four angular depressions which receive the cartilages of the third, fourth, fifth, and sixth ribs, while the inferior angle has a small facet, which, with a corresponding one on the xiphoid process, forms a notch for the cartilage of the seventh rib. These articular depressions are separated by a series of curved interarticular intervals, which diminish in length from above downward, and correspond to the intercostal spaces. Most of the cartilages belonging to the true ribs, as will be seen from the foregoing description, articulate with the sternum at the lines of junction of its primitive component segments. This is well seen in many of the lower animals, where the parts of the bone remain ununited longer than in man.