4 
NERVOUS CENTRES. (Human Anatomy. 
Fig. 368. 
atloido-vecipital articulation. 
_ (After Majendie. ) 
¢, the spinal cord. 
d, the dura mater and arachnoid membrane. 
, the sub-arachnoid space, divided into an 
rior and posterior portion by 
J, the ligamentum denticulatum. 
ection in the dorsal region. 
‘he same letters indicate similar parts as in A. 
n, the posterior median septum. 
% the roots of the nerves. 
_ We can thus demonstrate the existence of a 
fluid, which during life and in a state of health 
upies the sub-arachnoid cavity and main- 
ins the two layers of the arachnoid membrane 
‘contact with each other. This fluid is 
i by Majendie the . cerebro-spinal 
_ The first distinct recognition of this fluid in 
/ proper locality is due to Cotunnius, who 
the results of his observations in his 
emoir “ de Ischiade Nervosa,” preserved in 
Sandifort’s collection of dissertations. Cotun- 
hius was led to the discovery by remarking the 
on 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 
r attributes its having been so completely 
verlooked by previous anatomists to the fa- 
A, Transverse section of the spine at the situation of 
Tue Mentnces.) 
Fig. 369. 
639 
aitatrs 
Manes 
Mi 
Bag SOX VE 
AGE 
vy 
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, . 
B, 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 Physiologie 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 
