1308 



SURFACE ANATOMY AND SURFACE MARKINGS 



floor is partly formed by Rhomboideus major. If the scapula be drawn forward by 

 folding the arms across the chest, and the trunk bent forward, parts of the sixth 

 and seventh ribs and the interspace between them become subcutaneous and avail- 

 able for ausculation. The space is therefore known as the triangle of ausculation. 





r- Tr&pezius 



Pectoralis major 



Serralus anterior 



Obliquus exlernus 

 Reclus abdominis 



f Latissimus dorsi 



FIG. 1215. The left side of the thorax. 



Mamma. The size of the mamma is subject to great variations. In the adult 

 nulliparous female, it extends vertically from the second to the sixth rib, and 

 transversely from the side of the sternum to the midaxillary line. In the male and 

 in the nulliparous female the mammary papilla is situated in the fourth interspace 

 about 9 or 10 cm. from the middle line, or 2 cm. from the costochondral junction. 



SURFACE MARKINGS OF THE THORAX. 



Bony Landmarks. The second costal cartilage corresponding to the sternal 

 angle is so readily found that it is used as a starting-point from which to count the 

 ribs. The lower border of the Pectoralis major at its attachment corresponds to 

 the fifth rib; the uppermost visible digitation of Serratus anterior indicates the 

 sixth rib. 



The jugular notch is in the same horizontal plane as the lower border -of the body 

 of the second thoracic vertebra; the sternal angle is at the level of the fifth thoracic 

 vertebra, while the junction between the body and xiphoid process of the sternum 

 corresponds to the fibrocartilage between the ninth and tenth thoracic vertebrae. 



The influence of the obliquity of the ribs on horizontal levels in the thorax is 

 well shown by the following line. " If a horizontal line be drawn around the body 

 at the level of the inferior angle of the scapula, while the arms are at the sides, the 



