The anatomy of the nervous system, from the standpoint of development and function . ose elements of tactilesensibility, which underlie the appreciation of the form of objects or stereognosis,ascend uncrossed in the posterior funiculus to the gracile and euneate nuclei. Neuron III.—The neurons located in the ventral portion of the lateral nucleusof the thalamus, with which the tactile fibers of the second order enter into syn-aptic relations, send their axons by way of the thalamic radiation through theposterior limb of the internal capsule and the corona radiata to the somestheticarea of the
The anatomy of the nervous system, from the standpoint of development and function . ose elements of tactilesensibility, which underlie the appreciation of the form of objects or stereognosis,ascend uncrossed in the posterior funiculus to the gracile and euneate nuclei. Neuron III.—The neurons located in the ventral portion of the lateral nucleusof the thalamus, with which the tactile fibers of the second order enter into syn-aptic relations, send their axons by way of the thalamic radiation through theposterior limb of the internal capsule and the corona radiata to the somestheticarea of the cerebral cortex in the posterior central gyrus (Fig. 220). 3°6 THE NERVOUS SYSTEM THE SPINAL PATH FOR PAIN AND TEMPERATURE SENSATIONS Tain and temperature sensations are mediated by closely associated thoughnot identical paths, and it is convenient to consider them at the same time. Neuron I.—The first neuron of this system has its cell of origin located inthe spinal ganglion. Its axon divides into a peripheral branch, directed through Internal capsule Thalamus Mesencephalon. Medulla oblongata Lateral spinothalamic tract Spinal cord Dorsal root and spinal ganglion Fig. 231.—Diagram of the path for pain and temperature sensations. the peripheral nerve to the skin, or in the case of the pain fibers also to the deepertissues, and a central branch, which enters the spinal cord through the dorsalroot and almost at once terminates in the gray matter of the posterior gray column(Fig. 231). As was shown in Chapter VII, there is reason to believe that the [HE GREAT AITKKINl SYSTEMS 307 libers of painful sensibility, and possibly those of temperature sensationwell, are unmyelinated and enter the cud through the lateral division of thedorsal root to end in the substantia gelatinosa Rolandi. Neuron From these dorsal root fibers the Impulses arc transmitted(perhaps through the intermediation of one or more intercalated neurons) to theleurons of the second order. These have their
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