. Anatomy, descriptive and applied. Anatomy. 820 THE NERVE SYSTE3I for although the white substance is exclusively conducting substance, the gray is not exclusively ganglionic, for the former encroaches on the latter; in some local- ities, as in the ventral horns of the spinal gray, in parts of the cerebral cortex, in the reticular formation of the pons and medulla oblongata, and in the column of Clarke (dorsal nucleus), the admixture of myelinic fibres is considerable. Both white and gray substance is pervaded by the neuroglia. The specific graAaty of the cortical gray substance is ; of
. Anatomy, descriptive and applied. Anatomy. 820 THE NERVE SYSTE3I for although the white substance is exclusively conducting substance, the gray is not exclusively ganglionic, for the former encroaches on the latter; in some local- ities, as in the ventral horns of the spinal gray, in parts of the cerebral cortex, in the reticular formation of the pons and medulla oblongata, and in the column of Clarke (dorsal nucleus), the admixture of myelinic fibres is considerable. Both white and gray substance is pervaded by the neuroglia. The specific graAaty of the cortical gray substance is ; of the great gan- glia, ; of the gray substance in the cerebellum and mesencephalon, ; and of the white substance, For convenience of study, and somewhat in correspondence with phyletic development, the central axis of the nerve system is divided into (1) the spinal cord and (2) the brain, grossly subdivided into (a) medulla oblongata, pons, and cerebellum; (6) mid-brain; and (c) fore-brain. This gross subdivision is arbitrary and the interrelations of the parts would be obscured were two much stress laid upon any mode of separation. THE SPINAL CORD (MEDULLA SPINALIS; MYELON). The spinal cord is the attenuated, nearly cylindrical part of the cerebrospinal axis which lies in the vertebral canal, occupying its upper two-thirds in the adult. It extends from about the level of the atlooccipital articulation (or lower bor- der of the pyramid decussation) to the level of the lower border of the body of the first lumbar vertebra, where it terminates in a slender filament of gray substance enveloped by pia, and, further caudad, by a sheath of dura which is attached to the dorsum of the coccyx. The spinal cord is continuous. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gray, Henry, 1825-1861; Spitzka
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
