638 



SPINAL COLUMN 



the lateral limit in;; layer, and the postero-external 

 column, probably form connections lietween dif- 

 ferent levelti of the cord. Thus the postero- 

 external column is in great part formed of fibres 

 of the posterior roots passing upwards or down- 

 wards for a certain dUtance in it before entering 

 the postero-internal column ; while the antero- 

 lateral mixed zone contains fibres which connect 

 either nerve-cells at different level*, or more 

 probably nerve-cells of one level with fibres which 

 enter the anterior roots at another. 



Functions. The spinal cord provides paths for 

 the conduction of afferent and efferent impulses to 

 and from the brain, and also between different 

 portions of its own substance, as well as arrange- 

 ments for co-ordination of movements of the muscles 

 of the trunk and limbs, and centres for the regula- 

 tion of certain of the ' organic ' functions of the 

 body. 



Tne efferent impulses are motor, vasomotor, and 

 secretory. The path for the first of these is per- 

 fectly well known. It passes from the cerebral 

 cortex (motor area) through the internal capsule 

 and the anterior pyramids of the medulla mainly 

 to the crossed pyramidal tract of the opposite side, 

 and thence, as described, to the cells in tlie anterior 

 cornu. It is not yet known whether the ultimate 

 destination of the fibres of the direct pyramidal 

 tract is the cells of the anterior horn of the same or 

 those of the opposite side. The fibres from the vaso- 

 motor centre in the medulla in all probability pass 

 down in the crossed pyramidal tract and leave the 

 cord by the anterior roots. Division of their path 

 leads to paralysis of the muscular walls and dila- 

 tation of the arteries. This is only temporary, as 

 there are prol>ably also centres in the cord which 

 can act independently of those in the medulla. 

 The other efferent paths are unknown. 



The afferent paths transmit the various forms of 

 sensory impulses ; but, though we may perhaps 

 assume that those which degenerate upwards also 

 conduct in the same direction, it is remarkable 

 how little is known definitely about these. It is 

 generally held that impulses from the muscles 

 pass up the same side of the cord either in the 

 postero-median or direct cerebellar tracts ; while 

 the other sensory paths cross the cord as soon as 

 they enter it, and are continued upwards along the 

 other side. It is not determined whether the 

 crossing is complete, or whether the path is in the 

 white or gray matter or in both. Probably it is 

 not identical for each variety of sensation. There 

 is some reason to believe that impulses which give 

 rise to painful sensations travel up the ascending 

 antero-lateral tract. 



The cord also has in its anterior cornu cells 

 which, when stimulated either from the brain or 

 from the sensory nerves, originate voluntary or 

 reflex muscular movements. These cells fulfil too 

 the function of keeping up the general tone of the 

 muscles and also their nutrition, for when they are 

 destroyed the nerves and muscles connected with 

 them waste and disappear. In certain regions of 

 the cord these cells form centres for various of the 

 organic functions. These are found mostly in the 

 lower dorsal and lumbar regions. Recent experi- 

 mental research by Kerrier and Yeo has determined 

 the levels in the cord of the centres for the various 

 movements of the I im I - and trunk, and has already 

 given valuable results in practical surgery. 



See Quain's Anatomy, Obcreteiner'i Anatomy of the 

 Central Nrrroui Organ* (Hill's tran. ), Landou and 

 Stirling'* Phytioltxjy, and Foster's Phytioloyy. 



CURVATURE OF THE SPINE. There are two 

 main forms of this disease, which are due to differ- 

 ent causes viz. Angular Curvature or Pott's Cur- 

 vature, and Lateral Curvature. 



Angular curvature, which was first described 



by the famous surgeon Percival Pott (1713-88), 

 and is hence often named after him, is due to 

 disease of the bodies of the vertebra* and of 

 the intervertebral discs. It usually takes the 

 form of a tubercular disease of the bones, whieli 

 become carious and destroyed, and of ulcerntiim 

 of the discs between them. The result is tliat 

 the bodies of the diseased vertebrae give way and 

 the column becomes bent forward on itself, while 

 the spinous processes form a backward projection 

 opposite the diseased part hence the name angular 

 curvature. This projection is most marked when 

 the disease is in the dorsal region of the spine. If 

 the disease is arrested the Iwnes become firmly 

 united, and the curve of the spine becomes per- 

 manent. In unfavourable cases abscesses may 

 develop in the neighbourhood, and either press on 

 the spinal cord or on the spinal nerves, or burrow 

 in various directions, notably in the lumbar region 

 (psoas abscess). The disease is often set up by mi 

 injury which may be severe, such as the fulling of 

 a heavy weight on the back, or in children may !" 

 some trifling twist or fall, such as may occur during 

 rough play or from falling out of bed or from a 

 chair. It most often occurs in delicate children 

 with a tubercular family history, but it is by no 

 means unknown in those whose family and per- 

 sonal history is quite unexceptionable, and it may 

 even affect adults. Its early symptoms are often 

 obscure, and consequently may be overlooked at a 

 time when treatment is of most avail. There is at 

 first little or no deformity, but there may be pain 

 on percussing the spine of the affected vertebras. 

 There is also usually an avoidance of all movements 

 which may lead to jarring of the spinal column or 

 to painful pressure on the nerves. If the vertebras 

 of the neck are affected the child often support* 

 its chin by the hands, and does not willingly turn 

 its head round. Disease of the dorsal or lumbar 

 vertebrae is generally indicated by cautious move- 

 ments, especially in coming down a stair, the 

 avoidance of stooping or bending, or sudden twist- 

 ing of the body. A child will thus get down on its 

 knees to pick anything off the floor rather than 

 stoop. 



The treatment requires to be both local and con- 

 stitutional. It is always protracted for months 

 or even years. The general treatment is mainly 

 that required for strumous constitutions, such as 

 cod liver-oil, iron, hypophosphite of lime, &c. The 

 local treatment involves absolute rest in the re- 

 cumlwnt position in the early stage, with counter 

 irritation over the spine in the neighbourhood of 

 the disease. In later stages mechanical supports 

 are also required to keep the vertebra- from press- 

 ing on each other. The kind of support needed 

 varies with the region affected ; one very valuable 

 form for hospital practice consists in the applica- 

 tion, during the susi>ension of the patient, of a 

 plaster of Paris jacket to the body. The more 

 carefully rest in the recumbent position and 

 mechanical support are carried out, the less, as a 

 rule, will be the resulting deformity, the greater 

 the prospect of avoiding complications and of 

 obtaining permanent cure. 



Lateral curvature consists in a twisting of the 

 bodies of the vertebra on each other round their 

 vertical axis. It is sometimes a result of rickets, 

 but is far more frequently developed in growing girls 

 of feeble muscular development and general health, 

 between the ages of ten and sixteen. It is pro- 

 duced in the first instance by the continued main- 

 tenance of asymmetrical positions of the body, 

 such as by sitting sideways or cross-legged before a 

 school-desk, or by carrying a weight on one arm. 

 This curvature is usually to the right in the dorsal 

 region with a corresponding twist to the left in the 

 lumbar region. One shoulder, usually the right, 



