14 



THE SKELETON 



The pedicles of this voitebra are liable to a remarkable deviation from the conditions found 

 in other parts of the spine. The peculiarity consists of a complete solution in the continuity of 

 the arch inimediatelv behind the superior articular processes. In such sitecuuens the anterior 

 part consists of the body carryinji the pedicles, transverse and superior articular i)roce.sses ; win st 

 the posterior segment is coini)osed of the lamiiuB, spine, and inferior articular processes. J he 

 jiosterior segment of the ring of this vertebra may even consist of two pieces. There is reason to 



Fig. ir>.— Vakiatiox in the Fifth Lumbak Vektebka. (After Turner.) 



believe that this abnormality of the fifth lumbar vertebra occurs in five per cent, of all subjects 

 examined. Sir William Turner, in his report on the human skeletons in the Challenger 

 Reports, found seven examples among thirty skeletons examined. The skeletons in which this 

 occurred were : a Malay, an Andamanese, a Chinese, two Bushmen, an Esquimau, and a Negro. 

 Turner has also seen it in the skeleton of a Sandwich Islander. A similar condition is occasion- 

 ally met with either laterally or bilaterally in the thoracic vertebrae. 



Fig. 16.— a Variation in the Fifth Lumbak Vertebra. (After Turner.) 





.^„-^ 



Each of the five lumbar vertebrae is readily recognisable. The body of the first is deeper 

 behind than in iiont, the body of the second is of equal de]ith in front and behind, the bodies of 

 the third, fourth and fifth are deeper in front than behind, but the third has long transverse i>ro- 

 cesses and its lower articular facets are not very widely sejiarated ; the fourth has much shorter 

 transverse processes and the lower articular facets are very wide apart, and the filth is easily dis- 

 tinguished by the special leatures already described. 



THE SACRAL AND COCCYGEAL VEPxTEBR^ 



In the adult skck'ton, tlie five vertebnr sucoeedinj]^ the lumbar series are firmly 

 anlvvlosed to form a single bone, the sacrum : the components of the sacrum are 

 termed sacral vertt'brai. Beyond the fifth sacral, four, and occasionally five, other 

 rudimentary vertebne to which the adjective coccygeal is a])plicd. are ankylosed 

 in adult life, to form a single piece, the coccyx. In advanced life the coccyx 

 unites with the sacrum. 



