A manual of anatomy . y and laterally separating two grooves; the ventral, deeper, oneis for the subclavian vein, while the dorsal one is for the subclavian THE COSTAL CARTILAGES 39 artery and ventral division of the first thoracic nerve {sulcus sub-clavicB). Dorsal to the latter groove the surface is roughed for theattachment of the m. scalenius medius. The inferior surface issmooth and covered with pleura. The lateral margin is thickenedand rough dorsally for attachment of the first digitation of the anterior. In the second rib there is no twist and the surfaces are turned sothat
A manual of anatomy . y and laterally separating two grooves; the ventral, deeper, oneis for the subclavian vein, while the dorsal one is for the subclavian THE COSTAL CARTILAGES 39 artery and ventral division of the first thoracic nerve {sulcus sub-clavicB). Dorsal to the latter groove the surface is roughed for theattachment of the m. scalenius medius. The inferior surface issmooth and covered with pleura. The lateral margin is thickenedand rough dorsally for attachment of the first digitation of the anterior. In the second rib there is no twist and the surfaces are turned sothat they are obliquely directed. The head presents two facets andthe angle is distinct from the tubercle. The lateral surface presentsa roughened area for the attachment of part of the first and the entiresecond digitation of the m. serratus anterior. The margin likewiseaffords attachment to the external and internal intercostal muscles. On the tenth rib there is only one facet on the head and usuallynone on the Fig. 17.—The first rib of the right side seen from above and from the side. (Sobottaand McMurrich.) Fig. i8.—The second rib of the right side seen from above and from the side. (Sobottaand McMurrich.) On the eleventh and twelfth ribs the heads show only one facet; thetubercles and angles are faint. The ventral ends are pointed andtipped with cartilage. Both ribs are short. Ossification.—The ribs are of endochondral origin and each rib is developedfrom three centers, e.^cept the last two pairs. The center for the shaft appearsduring the ninth or tenth weelc of fetal hfe. The centers for the head and thetubercle appear about the to the twentieth years. Fusion is completeabout the twenty-fifth year. The last two ribs have two centers each, one forthe shaft and one for the liead. Muscles Attached.—The mm. intercostales interni et externi, scalenus an-terior, scalenus medius, scalenus posterior, pectoralis minor, serratus anterior,latissimus dorsi,
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecthumananatomy, bookyea
