. Cunningham's Text-book of anatomy. Anatomy. THE SPINAL NEEVES. 685 DESCRIPTION OF THE PEEIPHEEAL NEEVES AND SYMPATHETIC SYSTEM. I. The Spinal Nerves. Origin of the Spinal Nerves.—Each spinal nerve is attached to the spinal medulla by two roots, called respectively posterior (dorsal, afferent) and anterior (ventral, efferent). The posterior root is larger than the anterior root; it contains a larger number of radicular fibres, and the individual fibres are of larger size than in the anterior root. It has a vertical linear attach- ment to the postero-lateral sulcus of the spinal medulla. The f
. Cunningham's Text-book of anatomy. Anatomy. THE SPINAL NEEVES. 685 DESCRIPTION OF THE PEEIPHEEAL NEEVES AND SYMPATHETIC SYSTEM. I. The Spinal Nerves. Origin of the Spinal Nerves.—Each spinal nerve is attached to the spinal medulla by two roots, called respectively posterior (dorsal, afferent) and anterior (ventral, efferent). The posterior root is larger than the anterior root; it contains a larger number of radicular fibres, and the individual fibres are of larger size than in the anterior root. It has a vertical linear attach- ment to the postero-lateral sulcus of the spinal medulla. The fibres of contiguous posterior roots are in close relation, and, in some instances, overlap. The posterior root separates as it passes away from the spinal medulla into two bundles, both of which become connected with the proximal end of a spinal ganglion. Prom the distal end of this ganglion the posterior root proceeds to its junction with the anterior root in the intervertebral foramen. The spinal ganglia are found on the posterior roots of all the spinal nerves. (In the case of the first cervical or sub-occipital nerve, the spinal ganglion may be rudimentary or absent; and the posterior root itself may be wanting, or derived from the accessory nerve.) They occupy the intervertebral foramina, except in the case of the sacral and coccygeal nerves, the ganglia of which he vnthin the vertebral canal; and the first and second cervical nerves, the ganglia of which he upon the vertebral arches of the atlas and epistropheus respectively. "With the exception of the coccygeal ganglia they are outside the cavity of the dura mater, but are invested by the mem- brane. The ganglia are of ovoid form, bifurcated in some cases at their proximal ends. They consist of unipolar nerve-cells, whose axons, after a very short course, divide into central (root) and peripheral (trunk) fibres. The central fibres form the portion of the root entering the spinal medulla; the peri- pheral fibres ar
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
