NERVOUS CENTRES. (HUMAN ANATOMY. THE MENINGES.) 



639 



B 



A , Transverse section of tlie spine at the situation of 



atloido-occipital articulation. 

 (After Majendie.) 



c, the spinal cord. 



d, the dura mater and arachnoid membrane. 



s, s, the sub-arachnoid space, divided into an 

 anterior and posterior portion by 

 /, the ligamentum denticulatum. 



B, Section in the dorsal region. 



The same letters indicate similar parts as in A. 

 m, the posterior median septum. 

 n, the roots of the nerves. 



We can thus demonstrate the existence of a 

 fluid, which during life and in a state of health 

 occupies the sub-arachnoid cavity and main- 

 tains the two layers of the arachnoid membrane 

 in contact with each other. This fluid is 

 designated by Majendie the cerebro-spinul 

 fluid. 



The first distinct recognition of this fluid in 

 its proper locality is due to Cotunnius, who 

 stated the results of his observations in his 

 memoir " de Ischiade Nervosa," preserved in 

 Sandifort's collection of dissertations. Cotun- 

 nius was led to the discovery by remarking the 

 great disproportion between the dimensions of 

 the spinal canal and the bulk of its contents, 

 so that a considerable interval exists between 

 the internal surface of the former and the spinal 

 cord, which must be filled by something ; and 

 he attributes its having been so completely 

 overlooked by previous anatomists to the fa- 



B 



Sections of the spine in the lumbar region. 



A, shews the section of the cord as well as of 

 many roots of nerves descending to form the cauda 

 equina. 



R, shews the section of the cauda equina. 



In both these regions the sub-arachnoid space is 

 large and uninterrupted by bands or septa. The 

 fluid permeates between and surrounds the roots of 

 the nerves. 



shion of opening the head before the spine, 

 which favoured the escape of the fluid. This 

 anatomist was also aware that the fluid was 

 formed and contained in the sub-arachnoid 

 cavity. 



It is, however, to M. Majendie that we are 

 chiefly indebted for our present knowledge of 

 the physiological history of this fluid. Majen- 

 die's first researches were given to the public 

 in his Journal de Physiologic for the year 1827, 

 and he has lately collected the results of his 

 inquiries in a volume entitled " Recherches 

 Physiologiques et Cliniques sur le Liquide 

 Cephalo-rachidien," and published in 1842. 



The cerebro-spinal fluid is found wherever 



