Quain's elements of anatomy . tract (posteriormedian column). These are better marked in some individuals than inothers. INTEENAL STRUCTURE OF THE SPINAL CORD r RELATIVE PROPORTIONSOF GRET AND WHITE MATTER. Grey matter.—When the spinal cord is cut across (figs. 247, 248)it is seen that the grey matter occupies the more central parts, beingalmost completely enclosed by the white matter. The grey matterappears in the form of two irregularly crescentic portions on eitherside, united across the middle line by the posterior grey commissurebefore mentioned, so that its section may be compared in sha
Quain's elements of anatomy . tract (posteriormedian column). These are better marked in some individuals than inothers. INTEENAL STRUCTURE OF THE SPINAL CORD r RELATIVE PROPORTIONSOF GRET AND WHITE MATTER. Grey matter.—When the spinal cord is cut across (figs. 247, 248)it is seen that the grey matter occupies the more central parts, beingalmost completely enclosed by the white matter. The grey matterappears in the form of two irregularly crescentic portions on eitherside, united across the middle line by the posterior grey commissurebefore mentioned, so that its section may be compared in shape to theletter H. The concave side of each lateral crescent faces outwards,and in consequence of the depth of the posterior median fissurethe commissure of grey matter joins the crescents nearer theiranterior than their posterior ends, except in the lumbar region of thecord. The two horns or cornua of each crescent are named from their posi-tion anterior and posterior: the anterior cornu (fig. 247, a. c) is the Fiff. Fig. 247.—Section of the spinal cord in THE UPPER PART OF THE DORSAL REGION (E. A. S.). i a, anterior median fissure; p, posterior medianfissure ; j)- h posterior nerve-roots entering atthe postero-Iateral groove ; a. c, anterior cornuof grey matter ; p. c, posterior cornu ; i, inter-medio-lateral tract (lateral cornu) ; 2^- *» P^cessus reticularis; c, posterior vesicular columnof Clarke ; s, pia-matral septum forming thelateral boundary of the posterior median column. shorter and broader, and is everywhere separated from the surface of thecord by white matter which is traversed by the bundles of the anteriorroots at the part where these enter the cord. The posterior cornu{p. c ) is longer and narrower, and tapers almost to a point {apex cornuposterioris), which closely approaches the external surface of ^the cord atthe postero-Iateral sulcus, with which it is connected by fibres of theposterior roots (p. n), and between these by processes of the superf
Size: 1689px × 1479px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
