1892.] 



The Human Sacrum. 



521 



examples of abnormalities in the arrangement of the vertebral colnmn 

 have been carefully scrutinised in four important monographs. 

 Rosenberg's memoir has excited the most attention, as he has formu- 

 lated the theory of a phylog'enetic shortening of the human vertebral 

 column from behind forwards. He relies for his conclusions upon 

 the examination of abnormalities of the vertebral column of man and 

 the higher apes, and tbe statement of Kolliker, that the ilium in the 

 process of development at first articulates with hinder segments, and 

 gradually shifts forwards along the vertebrae to be connected with 

 segments placed more anteriorly. Thus Rosenberg regards a human 

 vertebral column with an increased number of presacral vertebras as 

 an " ancestral " form : a column with a diminution in the number of 

 presacral segments as a " future " form, representing a more recent 

 phylogenetic process. Topinard has recorded a number of observa- 

 tions on vertebral abnormalities. He considers that anomalies in the 

 thoracic and lumbar regions may be due to excess, default, or com- 

 pensatory variations ; that the anomalies of the sacrum are always 

 compensatory, depending partly upon the relation of the ilium to the 

 vertebral column-, and partly upon the atrophy and fusion of the 

 caudal vertebras. He thus gives a qualified support to the notion of 

 intercalation and excalation of vertebras, as far as the thoracic and 

 lumbar vertebras are concerned. Regalia and Holl both reject 

 Rosenberg's " atavistic " hypothesis as inadequate. Regalia re- 

 gards thoracico-lumbar variations as caused by correlated variations 

 in the position and proportions of the thoracic and abdominal viscera ; 

 and agrees with previous authors that lumbo-sacrai and sacro-caudal 

 abnormalities are due to alterations in the position of the ilium in 

 relation to the vertebral column. Holl, from embryological investi- 

 gations, considers that the sacrum, once formed, undergoes no altera- 

 tions, and that the 25th vertebral segment is, as a rule, the first 

 sacral vertebra from the earliest time. He also asserts that the same 

 segment (v. fulcralis) has in the great majority of cases in the adult 

 the main attachment of the ilium. He looks upon variations at the 

 cephalic end of the sacrum as caused by changes in the position of 

 the ilium ; variations at the caudal end, as associated with fusion of 

 the coccyx. 



The present memoir deals with the characteristics of the human 

 sacrum, its form and anomalies, its correlation to other regions of the 

 vertebral column in man and other mammals, its relation to the 

 spinal nervous system, and its ossification, especially in relation to 

 that aspect of the question brought into prominence by Rosenberg's 

 hypothesis. The sacral index and the sacral curve are also dealt 

 with. 



The investigations have been made in a series of 265 adult sacra 

 and numerous fcetal vertebral columns. Of the adult sacra, 36 



