. Cunningham's Text-book of anatomy. Anatomy. 558 THE NEKVOUS SYSTEM. Funiculus gracilis Gracile nucleus Funiculus cuneatus Cuneate nucleus. Tractus spinalis of trigeminal nerve According to Sherrington, an anterior cerebrospinal tract in the spinal medulla of the anthropoid apes stands in connexion with the arm-centre in the cerebral cortex. If this is the case in man it must have other connexions as well, seeing that it is carried down the spinal medulla for a considerable distance beyond the level of the spinal segments which give motor fibres to the upper limb. In the lower apes an anterio
. Cunningham's Text-book of anatomy. Anatomy. 558 THE NEKVOUS SYSTEM. Funiculus gracilis Gracile nucleus Funiculus cuneatus Cuneate nucleus. Tractus spinalis of trigeminal nerve According to Sherrington, an anterior cerebrospinal tract in the spinal medulla of the anthropoid apes stands in connexion with the arm-centre in the cerebral cortex. If this is the case in man it must have other connexions as well, seeing that it is carried down the spinal medulla for a considerable distance beyond the level of the spinal segments which give motor fibres to the upper limb. In the lower apes an anterior cerebro-spinal tract does not seem to exist: the whole pyramid crosses over to the op- posite side of the spinal medulla in the shape of the lateral cerebro- spinal tract. y» Nucleus tractus itVl&r" As we have noted, V^ll the decussating pyra- midal bundles pass through the anterior column of gray mat- ter, and cut it into two portions (Figs. 489 and 490). The basal part remains in position on the an- terior and lateral aspect of the central canal, and forms part of the thick layer of gray matter which surrounds it. The detached head of the anterior column is set free; and from the large multipolar cells which lie in its midst some of the fibres of the anterior root of the first cervica^ nerve, and also some of the root fibres of the accessory nerve, take origin. As we proceed into the medulla oblongata another effect of the decussation of the pyramids is seen in the submergence from the surface of the strand of fibres which, in the anterior funiculus of the spinal medulla, lies to the lateral side of the anterior cerebro-spinal tract, and which receives the name of the fasciculus anterior proprius. While the decussation is going on the fasciculus proprius is thrust aside, and in the medulla oblongata, it takes up its position as a flattened band-like strand on ^-^-^TV > yf -~^~\ â -â Funiculus gracilis Oracile nucleus- Central gray matter Central canal Fasci
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