THE SPINAL CORD. 



759 



Structure. — ludependeiitly of the epithelium mentioned when describing 

 the ependymis, neuroglia, nerve-fibres, nerve-cells, and vessels enter into the 

 structm'e of the spinal cord. 



The neuroglia has l)eeu compared to a kind of sponge (the so-called spongy 

 matter), in the spaces of which are the other elements of the cord. It exists in 

 the white and the grey mattei^s, but it is more abundant in the superior grey 

 cornna than in the inferior cornua. It surrounds the upper extremity of the 

 former, in beco.ning softer and more transparent, and is here designated the 

 geUitinous substance of Rolando (substantia gelatinoso Eolandi). It constitutes, 



TRANSVERSE StCTION OF SPINAL CORP THROLTiH THE MIDDLE OF THE LUMBAR REGION, SHOWING 

 ON THE RIGHT SIDE THE COURSE OF THE NERVE-ROOTS, AND ON THE LEFT THE POSITION OF 

 THE PRINCIPAL TRACTS OF VESICULAR 5IATTER. 



A, A, Inferior columns; p, p, superior columns; L, L, lateral columns; a, inferior median fissure; 

 JO. superior median fissure; 6, 6, 6, b, inferior roots of spinal nerves: c, c, superior roots; 

 d, d. tracts of vesicular matter in'supprior column ; e, traits of vesicular matter in inferior column 

 f, central canal ; g, substantia gelatinosa. 



in great part, the grey commissure, and can be deeply stained by the carminate 

 of ammonia. 



The neuroglia is associated with a small quantity of connective tissue, which 

 entere the cord along with the vessels. It is formed of a mass of cells, the mem- 



regions either a depression on the surface of the cord, or oa its substance a fasciculus of 

 connective tissue, or a vessel larger tlian in other points. 



The systematic lesions of the coid not having yet been observed in the domestic animals, it 

 cannot he stated at what point the distinctions established in the human spinal cord are justified, 

 80 far as that of the Horse is concerned. In some sections of the cord of that animal, it would 

 appear that the fasciculus of Turck is distinct from the other parts of the anterior column; 

 but iu a great number the teparalion is extremely vague. The cdumns of Goll alone are very 

 distinct in the superior portion of the cervical region. They are especially visible in the Dog. 



In fact, at the presi^nt time the topography of the human spinal cord cannot be without 

 uncertainty when applied to that of animals; but the eflforts of pathologists and anatomists 

 should be directed to dissipating this uncertainty. 



