. Cunningham's Text-book of anatomy. Anatomy. THE THORAX- AS A WHOLE. 113 THE COSTAL CARTILAGES. The costal cartilages, of which there are twelve pairs, are bars of hyaline cartilage united to the anterior extremities of the ribs, into which they are recessed and held in position by the periosteum. Through these cartilages the first seven ribs are con- nected directly with the sternum by means of synovial joints corresponding to the notches along the margins of the breast bone. To this there is an exception in the case of the first rib, the cartilage of which is directly blended with the manub
. Cunningham's Text-book of anatomy. Anatomy. THE THORAX- AS A WHOLE. 113 THE COSTAL CARTILAGES. The costal cartilages, of which there are twelve pairs, are bars of hyaline cartilage united to the anterior extremities of the ribs, into which they are recessed and held in position by the periosteum. Through these cartilages the first seven ribs are con- nected directly with the sternum by means of synovial joints corresponding to the notches along the margins of the breast bone. To this there is an exception in the case of the first rib, the cartilage of which is directly blended with the manubrium sterni. The eighth, ninth, and tenth are connected indirectly with the sternum by their union with each other, and their articulation, through the medium of the eighth, with the seventh rib cartilage, whilst the eleventh and twelfth cartilages tip the ribs to which they belong, and lie free in the muscles of the flank. The costal cartilages increase in length from the first to the seventh, below which they become shorter. The first inclines obliquely downwards and medially to unite with the superior angle of the manubrium. The second lies more or less horizontally. The third to the seventh gradually become more and more curved, inclining downward from the extremities of their respective ribs, and then turning upwards to reach the sternum. The tenth cartilage articulates by means of a synovial joint with the ninth, the ninth with the eighth, and the eighth with the seventh. There are also surfaces for the articulation of the seventh with the sixth, and sometimes for the sixth with the fifth. THE THORAX AS A WHOLE. The bony and cartilaginous thorax is barrel-shaped, being narrower above than below, and compressed from before backwards. Its posterior wall is longer than its anterior, and its transverse width, which reaches its maximum opposite the eighth or ninth rib, is much in excess of its sagittal diameter. This is largely owing to the forward projec- tion of the thoracic
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
