714 NERVOUS SYSTEM. (NERVOUS CENTRES. ABNORMAL ANATOMY.) 



but, being of small size, it escaped the notice 

 of the observer. 



This explanation is likewise confirmed by the 

 occurrence of cases (rare, it is true) in which 

 the brain existed, but the spinal cord was 

 wanting. A very able narrative of a case of this 

 kind has lately been published by Dr. Lonsdale 

 of Edinburgh. " The anterior and middle 

 lobes of the brain appeared to be properly 

 developed, and occupied their usual positions 

 in the cranial cavity; whilst the posterior lobes 

 were much smaller, and were partially squeezed 

 through a large abnormal opening or deficiency 

 in the occipital bone. The cerebellum and 

 that part of the occipital bone in which it is 

 normally lodged, were wanting. There was not 

 the slightest vestige of medulla oblongata or 

 spinal cord, and the posterior arches of the 

 vertebrae did not exist."* The foetus had 

 reached its full term, and its body and limbs 

 were well formed. 



An interesting feature which had been well 

 observed in this case, although probably not 

 peculiar to it, but hitherto overlooked, was the 

 relation of the nerves in the cranial and spinal 

 cavities. All the nerves of the medulla oblon- 

 gata, and the first, second, and third cervical 

 nerves, hung as loose threads in the cranial 

 cavity or in the upper part of the spinal canal, 

 and presented a looped arrangement, seeming to 

 denote that such is their normal disposition in 

 the nervous centre. 



Partial deficiencies of the spinal cord, al- 

 though also rare, are more frequent than the 

 total absence of the organ. These occur in 

 connection with other defects of developement. 

 Thus, in spina bifida much of the cord is defi- 

 cient, either throughout its entire extent or in 

 those parts where the vertebral wall is defective. 

 In such cases it is probable that the deficiency 

 is attributable to the destructive influence of the 

 dropsical effusion rather than to an original de- 

 fect of the organ. In cases in which the upper 

 or the lower extremities have not been deve- 

 loped, the usual cervical or lumbar swelling is 

 imperfectly developed, owing to the absence or 

 atrophy of the fibres which would have formed 

 the nerves to those limbs. 



Excessive congenital developement of the 

 spinal cord occurs only in those monstrosities 

 which arise from the junction or fusion of the 

 spinal columns of two embryos. 



The diseased states of the spinal cord may be 

 enumerated as follows : hypertrophy, atrophy, 

 induration, softening, suppuration, deposits of 

 tubercle or of other morbid products. 



In hypertrophy, the cord is enlarged and 

 looks full and plump, without any alteration of 

 its consistence or of its intimate structure. It 

 is not improbable that the elementary fibres as 

 well as the vesicles of grey matter may be en- 

 larged in such cases, and that the increased 

 dimensions of the whole organ must be attri- 

 buted to this cause, and not to the deposition 

 of any new material in it. I have not, however, 

 had any opportunity of ascertaining this point 

 by microscopic examination. 



* Edin. Med. and Surg. Journal. 



Atrophy occurs in the cord generally as the 

 result of some local pressure from a tumour 

 developed in connection with some one of the 

 membranes or external to them. In a case of 

 this kind which I lately examined, the tumour 

 consisted of a mass of scrofulous matter situate 

 between the vertebrae and the dura mater in the 

 upper part of the dorsal region. That part of 

 the cord which was pressed upon by the tumour 

 was wasted to one-half its natural size, whilst 

 below it the cord exhibited its natural size. 



Atrophy of the cord occurs as part of that 

 general wasting of the nervous centres which 

 accompanies advanced life, or a state of general 

 cachexy. In persons long bedridden the cord 

 is found in a wasted state ; and in cases of ex- 

 tensive hysterical paralysis, in which exercise of 

 the enfeebled limbs has been neglected, the 

 cord will participate in the wasting of the nerves 

 which supply the affected parts. 



Induration of the cord is not of unfrequent 

 occurrence, and appears to be the result of 

 some abnormal nutrition analogous to if not 

 identical with chronic inflammation inflam- 

 mation modified, perhaps, in the nature of its 

 event by some peculiar state of the blood. The 

 hardness occurs generally in patches, involving 

 more or less of the thickness of the cord, and 

 affecting the peripheral parts of the body, in pro- 

 portion as it involves the immediate points of 

 implantation of the roots of the nerves, or those 

 roots themselves. It is generally accompanied 

 by some discolouration of a light brownish hue, 

 as if the first changes which gave rise to it were 

 attended with extravasation of the colouring 

 matter of the blood. 



Sometimes, however, induration seems to re- 

 sult from the changes which accompany atro- 

 phy of the cord, as if from an imperfect sup- 

 ply of the fluids necessary for perfect nutrition. 



Softening of the cord is found in two states, 

 which are probably essentially different in their 

 intrinsic nature and origin. One is that of red 

 softening; the other is that of white or colourless 

 softening. In the former the tissue of the 

 spinal cord is much softer than it ought to be, 

 and is readily disintegrated by a stream of 

 water directed upon it ; its colour is due to the 

 full injection of the bloodvessels which tra- 

 verse it, or to some extravasated blood. In the 

 latter the nervous matter is reduced to a soft 

 semifluid mass, like thick cream, without the 

 least appearance of injected vessels. In the 

 former the nerve fibres are more or less broken 

 down and softened; in the latter there is little or 

 no breaking down of the fibres, but they are at- 

 tenuated and have lost the distinctive characters 

 of the white substn nee and central axis to a greater 

 or less degree. Red softening appears to be in- 

 flammatory in its origin, but white softening in- 

 dicates a deficient supply of blood, and so far 

 resembles the gangrene which occurs in external 

 soft parts. 



The anatomist should be prepared to distin- 

 guish the white softening, which is the product 

 of a morbid process during life, from that 

 which occurs after death as the result of decom- 

 position, or which may be produced by violent 

 compression of a part of the cord in opening 



