STERNUM 83 



on the transverse processes for the tubercles of the ribs. The 

 facets 011 the bodies are usually placed midway on adjacent 

 bodies, so that a demi-facet is found on the upper and lower 

 margins of bodies. 



The Vertebral Column as a whole. The vertebra are so 

 articulated that the bodies, transverse processes, and spinous 

 processes are all superimposed. This causes posteriorly two 

 longitudinal grooves, one each side of the spine, in which are 

 placed the longitudinal muscles of the back. 



Viewed from the side, it is seen that the column forms 

 a series of curves, slightly forward in the cervical region, 

 markedly backward in the thoracic region, and forward again 

 in the lumbar region. The sacrum, again, is convex backwards, 

 and the junction of the fifth lumbar vertebra with the sacrum is 

 called the sacro-vertebral angle, which is always very marked. 



Ossification. Centres for the bodies and neural arches appear 

 before birth. At puberty, epiphyses for the different processes 

 and upper and lower surfaces of the bodies appear. All become 

 completely fused about the twenty-fifth year. 



The Sternum, or Breast-Bone, is in the middle of the upper 

 part of the anterior wall of the thorax. It articulates on each 

 side with the upper seven ribs and the clavicle. It consists of 

 three parts the manubrium or presternum, the body, and the 

 ensiform or xiphoid cartilage. 



The Manubrium is separate from the body, although occa- 

 sionally it is found to be fused. It is a flattened, four-sided 

 bone, the upper end being wider than the lower. At the 

 superior angles it articulates with the first rib on each side, 

 and immediately in front of this articulation on the upper 

 margin are the facets for articulation with the clavicles, be- 

 tween which is the suprasternal notch. At its junction with the 

 body is found the articulation for the second rib. 



The Body of the Sternum is a long-shaped flat bone, with its 

 f-ddes notched for articulation with the second to the seventh ribs 

 inclusive. At its upper end it articulates with the manubrium, 

 and at the lower end is attached the ensiform cartilage, a pointed 

 process which is partly ossified. 



The Sternum lies obliquely downwards and forwards in the 



