. Anatomy, descriptive and applied. Anatomy. THE SPINAL CORD 829 This functional differentiation of the neural axis into sensor and motor divisions apparently finds organic expression in an important modification of the developing neural tube. Each lateral wall of the neural tube is early demarcated into a dorsal and a ventral lamina and the slit-like central canal becomes more or less lozenge-shaped on trans-section, owing to the forma- tion of a lateral longitudinal furrow within. The dorsal lamina or zone is preponderatingly sensor in function, while the ventral zone is principally motor in
. Anatomy, descriptive and applied. Anatomy. THE SPINAL CORD 829 This functional differentiation of the neural axis into sensor and motor divisions apparently finds organic expression in an important modification of the developing neural tube. Each lateral wall of the neural tube is early demarcated into a dorsal and a ventral lamina and the slit-like central canal becomes more or less lozenge-shaped on trans-section, owing to the forma- tion of a lateral longitudinal furrow within. The dorsal lamina or zone is preponderatingly sensor in function, while the ventral zone is principally motor in function. This fundamental fact has been of the greatest aid in the correct interpretation of many hitherto obscure facts re- garding the mechanism of the nerve system, and will be found to underlie our method of descrip- tion throughout. The muscular supply from motor segments of the cord is shown in Fig. 604, and the cutaneous supply in Fig. 605. Internal Structure of the Spinal Cord.—If a transverse section of the spinal cord be made, it will be seen to consist of white and gray nerve substance. The white substance is made up of myelinated axones; the gray contains the cell bodies of neurones and nonmyelinated axones with only few myelinated axones. The color of the gray substance, so-called, varies according to the degree of capil- lary injection and the age of the individual. It is usually of a faint, reddish-gray tinge, the gray preponderating in older persons, but various shades of red, yellow, -LATERAL. ERAL HORN TRAL HORN *''V7-R),L BOC* VENTRAL FISSURE Fig. 606.—Trans-section of the spinal cord at the mid-thoracic region. and light slate-color may be noted. Nor is the color uniform even in the same section. Around the central canal and at the periphery of the dorsal horn the gray substance is very translucent and is termed, according to its situation, the gelatinosa centralis (gliosa centralis) and gelatinosa Rolandi or caput gliosum (gliosa cornualis). The white
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
