. Cunningham's Text-book of anatomy. Anatomy. THE SPIRAL MEDULLA. 521 stance, composed at first mainly of the axons intercalated cells in the spinal medulla; and as these funiculi increase in size they help to mould the form of the columnse grisese. This is displayed best in the case of the posterior column ( posterior cornu). The major portion of the white substance, funiculus posterior, which accumulates behind (and after- wards lies on the medial side of) the posterior column, does not consist of fibres springing from intercalated cells, either of the spinal medulla or any other part of
. Cunningham's Text-book of anatomy. Anatomy. THE SPIRAL MEDULLA. 521 stance, composed at first mainly of the axons intercalated cells in the spinal medulla; and as these funiculi increase in size they help to mould the form of the columnse grisese. This is displayed best in the case of the posterior column ( posterior cornu). The major portion of the white substance, funiculus posterior, which accumulates behind (and after- wards lies on the medial side of) the posterior column, does not consist of fibres springing from intercalated cells, either of the spinal medulla or any other part of the central nervous system, but of the direct continua- tions of the central processes of the cells in the spinal ganglion on the posterior root (Figs. 463 and 464). A large proportion of the fibres of the posterior root do not enter the gray columns immediately after their insertion into the alar lamina, but bifurcate to form two vertical nerve-fibres, one passing upwards, and the other downwards, in the funiculus posterior before they end in the columna grisea, some distance above or below the place where they gained admission to the medulla spinalis. As the spinal medulla grows, the originally blunt columna posterior becomes drawn backwards into an increasingly attenuated process, and the funiculus posterior, which was placed originally upon its lateral surface (Fig. 464, A), and then upon its posterior surface (,B), gradually assumes a wedge-shaped form (Figs. 464, C, and 466), upon the medial side of the gray matter. Development of the Anterior Median Fissure, Posterior Median Septum, and of the Central Canal.—As the anterior columns of gray matter and the anterior funiculi of white matter increase in size, the anterior surface of the spinal medulla, on either side of the median plane, bulges forwards, and the fissura mediana anterior (Fig. 464, A, B, and C) is produced as the natural result. There has been considerable discussion as to the mode of formation of t
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
