Fig. 8. Course of Fibres from Cortex to Spinal Cord. 



This section is not accurately in the Frontal plane but is directed some- 

 what obliquely so that above it passes through the Praecentral Convolution and 

 below through the middle of the Pons. At the Point marked Z it passes through 

 the Posterior Perforated Spot. A transverse section of the cord has been added 

 in order to shew the topographical relations of the long cerebral tracts to the 

 columns of the spinal cord. The posterior limb of the internal capsule is divided 

 and the pyramidal tract is seen running from the motor area, through the posterior 

 limb, to the middle third of the ventral portion of the Pons; at the Bulb (Decus- 

 sation of the Pyramids) these fibres cross the middle line and continue their course 

 in the Lateral Columns of the Cord, whence they pass to arborize around the 

 Anterior Cornual Cells which give off the fibres of the peripheral nerve. 



The fibres of the pyramidal tract which arborise around the Nucleus of 

 the Facial Nerve of the opposite side cross the middle line in the Pons. The 

 course of the Facial Fibres and the Facial Nucleus is schematic. (Cf. Fig. 6 Text.) 



The Posterior Columns of the Spinal Cord contain the path of the "Muscle- 

 Sense". Probably the fibres from the lower extremity lie in the tract of GOLL in 

 the cervical region and those from the upper limb in the tract of BuRDACH. 

 These tracts decussate in the Bulb, practically opposite the Decussation of the 

 Pyramids. The further course of this path is known as the "mesial fillet"; the 

 fibres end parti}' in the Corpora Quadrigemina, partly in the Thalamus and partly, 

 after tracking through the posterior limb of the internal capsule, in the cortex 

 of the Parietal I^obe. 



The Occipito - temporal cortico - pontic tract (previousl)^ mentioned in 

 Fig. 7), appears again in the outer Ygrd of the base of the Pons, arborising around 

 the Nuclei of the Pons whence new fibres cross the middle line to reach the 

 Cerebellum through the Middle Cerebellar Peduncles. The Optic Tract is cut 

 transversely, the anterior commissure obliquely — its fibres pass to the Olfactory 

 Area, to the Hippocampal convolution. 



The Caudate Nucleus is again cut in 2 places, at the commencement of 

 its tail near the Thalamus and at its termination in the descending horn. The 

 Fimbria represents the termination of the Fornix which in its course along the 

 lower aspect of the Corpus Callosum has 2 (posterior) columns which, after diverg- 

 ing, ascend in the form of an arch with its convexity backwards to finally (this 

 is the part called the Fimbria) join the floor of the ventricle. The gray matter 

 situated between the Cortex and the Fimbria is the Fascia Dentata; above these 

 structures (Fimbria and Fascia Dentata) is the Lateral Choroid Plexus. This is not 

 indicated in the figure. It is probable that the Lateral Choroid Plexus does not 

 close in the descending horn of the Lateral Ventricle completely but allows the 

 intra-ventricular cerebro-spinal fluid to communicate with that of the basal sub- 

 arachnoid spaces. Ziehen. 



