510 



THE SPIXAL CORD. 



The nerve-cells of the grey matter are of two kinds. Firstly, there are very large 

 branched cells, from ^ to ^ of an inch in size, containing nuclei and pigment ; 

 secondly, there are smaller cells, ranging from ^^ to ^ of an inch, but the majority 

 are from -^^ to ~ of an inch in size. 



The smaller cells occur scattered throughout the whole of the grey matter ; the 

 larger cells, on the contrary, are collected into groups. In the posterior cornua the 

 large cells are almost entirely collected into a compact group, the posterior vesicular 

 column of Clarke (the core of Stilling), which occupies the inner half of the cervix of 

 the posterior cornu. This vesicular column is in intimate connection with the 

 posterior roots of the nerves ; it may be traced continuously from near the lower 

 extremity of the spinal cord to the middle of the cervical enlargement, where it 

 terminates ; and it increases in size in both the lumbar and cervical enlargements. 

 In the anterior cornu the large cells occur in greater number than in the posterior 

 cornu, and are of somewhat greater size ; and they are principally placed at its forepart, 

 and arranged in an inner and an outer group. There is likewise described by Clarke a 

 small group of cells, collected in a tractus intermedio-lateralis, and forming a projection 

 of the grey matter opposite the junction of the anterior and posterior cornua. This 

 lateral vesicular column extends from the upper part of the lumbar to the lower part 

 of the cervical enlargement ; and it may be said to reappear at the upper extremity 

 of the cord, where it is traversed by the roots of the spinal accessory nerve, and is 

 continued up into the medulla oblongata. 



Fig. 346. 



Fig. 346. A SMALL PORTION OF A TRANSVERSE SECTION OP THE HUMAN SPINAL CORD 



NEAR THE SURFACE AT THE ENTRANCE OP A BUNDLE OF THE ANTERIOR ROOTS. ^ 



This figure, which is somewhat diagrammatic, is intended to show the relation to the 

 nervous substance of the pia-matral sheath of the cord and the processes of connective 

 tissue prolonged from it between the longitudinal and other nerve fibres, a, a, the 

 primitive filaments of a bundle of the anterior roots, the medullary sheaths not repre- 

 sented ; b, b, transverse sections of part of the anterior columns of the cord in which the 

 dark points are the primitive filaments, and the circles represent the neurilemmal tube 

 enclosing the medullary substance : in these parts the connective tissue is not represented, 

 and many of the smallest nerve-fibres have also, for the sake of clearness, been omitted ; 

 c, the pia-matral covering of the cord ; d, one of the compartments of the anterior 

 column enclosed by septa of connective tissue prolonged from the pia mater, and exhibit- 

 ing the fine frame-work of connective tissue extending through among the nerve-fibres, 

 which last have been omitted : there are also indicated among the trabeculse minute 

 nuclei of connective tissue. 



Connective tissue takes part in the structure of the cord to a very considerable 

 extent. It forms a complete covering surrounding the white substance. In the 

 inner margin also of the posterior columns, one on each side of the posterior fissure, 

 two wedge-shaped bands (the bands of Goll) have been distinguished, in which the 



