A. SPINAL CORD 

 Structure 



THE spinal cord is a more or less cylindrical mass of nerve 

 tissue which passes from the base of the brain down the 

 vertebral canal. There are two enlargements upon it, one in 

 the cervical region, one in the lumbar region, and from these 



FIG. 78. Cross Section of the Spinal Cord through the Second Dorsal Segment, 

 to show disposition of grey and white matter. P., dorsal horn ; A., 

 ventral horn with large cells ; I.L., intermedio-lateral liorn with small 

 cells ; L.C., Lockhart Clarke's column of cells ; P.M. and P.L. 

 dorso-median and doi so-lateral columns ; D.C., direct cerebellar tract 

 Asc, and Desc. Ant. Lat., ascending and descending ventro-lateral or spino- 

 ventral tracts ; B.B., basis bundles ; C.Py., crossed pyramidal tract ; O.Py., 

 direct pyramidal tract. On opposite side, tracts which degenerate head- 

 wards are marked with horizontal lines ; tracts degenerating from the 

 head with vertical lines. (After BUUGK.) 



the nerves to the arms and legs come off. A fine central 

 canal runs down the middle, and the two sides are almost 

 completely separated from one another by a ventral and 

 a dorsal mesial fissure (fig. 78). Each half is composed of 

 a core of grey matter arranged in two processes or horns 



