. Text-book of normal histology: including an account of the development of the tissues and of the organs. Section of injected spinal cord of child : s, sulcal branch of anterior spinal artery occupying anteriormedian fissure ; c, c, sulco-conimissural vessels from sulcal artery passing to gray matter to formdense net-work ; /, posterior spinal artery, sending off twigs to white matter; around margin of cordnumerous peripheral vessels enter white substance to form open net-work. crescents ; a branch of some size passes backward to supply theregion corresponding to Clarkes column. The sulco-com
. Text-book of normal histology: including an account of the development of the tissues and of the organs. Section of injected spinal cord of child : s, sulcal branch of anterior spinal artery occupying anteriormedian fissure ; c, c, sulco-conimissural vessels from sulcal artery passing to gray matter to formdense net-work ; /, posterior spinal artery, sending off twigs to white matter; around margin of cordnumerous peripheral vessels enter white substance to form open net-work. crescents ; a branch of some size passes backward to supply theregion corresponding to Clarkes column. The sulco-commissuralartery likewise gives off vertical anastomosing branches, onepassing brainward, the other caudalward, to unite with similar off-shoots from the corresponding arteries of different planes. The veinsfollow in general the course of the corresponding arteries : some ofthe blood, however, brought by the sulcal artery is carried off by theperipheral veins. THE MEDULLA. The differences between the medulla and the spinal cord arerather of arrangement than of any great variation in structural Fig. ^„5 NORMAL HISTOLOGY. elements, since the tissues of the cord are prolonged into the medulla,where the increased importance of parts before relatively incon-spicuous, together with the addition of new masses of nervous matter,lirings about the redisposition of the structures continued fromthe cord. The ciiangcs taking place in the transition of the cordinto the medulla consist primarily in a modification of the graymatter; the principal factors are the gradual increase in the sizeof the tracts of the posterior column and the decussation of fibresfrom the lateral column destined to aid in forming the anterior pyra-mids. The changes wrought by the firstfactor are earliest indicated, and affect par-ticularly the posterior cornua of the graysubstance, while the second modifies theanterior horns. An intimation of the changes to followis seen in sections as low as the first, oreven second,
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherphiladelphiajblipp
