Sternum

The sternum , sternum, is an unpaired bone of elongated shape with a slightly convex anterior surface and a concave posterior surface, respectively. The sternum occupies the section of the anterior wall of the thorax. It distinguishes between the handle, the body and the xiphoid process. All these three parts are joined together by cartilaginous layers, which age with ossification.

The sternum handle , manubrium sterni, is the widest part, thick at the top, thinner and already below, has on the upper edge a jugular incision, incisura jugularis, easily palpable through the skin. On the sides of the jugular notch are clavic notches, incisurae claviculares, the places of articulation of the sternum with the sternal ends of the clavicles.

Somewhat lower, on the lateral margin, is the notch of the 1st rib, incisura costalis I, - the site of adhesion to the cartilage of the 1st rib. Still below there is a small indentation - the upper part of the rib rib II of the rib; The lower part of this notch is on the body of the sternum.

The body of the sternum, corpus sterni, is almost 3 times longer than the arm, but already it. The body of the sternum in women is shorter than that of men.

The anterior surface of the sternum has traces of fusion of its parts in the process of embryonic development in the form of weakly expressed transversely extending lines.

The cartilaginous connection of the upper edge of the body with the lower edge of the handle was called synchondrosis of the sternum arm , synchondrosis manubriosternalis, with the body and handle converging, forming a blunt, open-back angle of the sternum, angulus sterni. This protrusion is at the level of the articulation of the second rib with the sternum and is easily probed through the skin.

On the lateral edge of the sternum body distinguish four complete and two incomplete costal incisions, incisurae costales. - places of articulation of the sternum with cartilages of II-VII ribs. One incomplete notch is located at the top of the lateral edge of the sternum and corresponds to the cartilage of the second rib, the other - at the bottom of the lateral margin and corresponds to the cartilage of the VI rib; Four complete cuttings lie between them and correspond to the III-VI ribs.

The portions of the lateral sections lying between two adjacent costal incisions are in the form of semilunar depressions.

The xiphoidus processus, the shortest part of the sternum, can be different in size and shape, with a split apex or with a hole in the middle. The acute or blunt apex is facing either anteriorly or posteriorly. In the upper lateral section of the xiphoid process there is an incomplete notch that articulates with the cartilage of the VII rib.

The xiphoid process forms with the body of the sternum synochondrosis of the xiphoid process , synchondrosis xiphosternalis. By age, the xiphoid process, ossified, fuses with the body of the sternum.

Sometimes higher than the arms of the sternum, in the thickness of the subnatal muscle group or in the medial stalk of the sternocleidomastoid muscle , there are 1-3 loaded bones, ossa suprasternalia. They are articulated with the sternum handle.

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