838 



NEUROLOGY 



GENiCULATE 



PORTION OF 



MOTOR TRACT 



(FOR MUSCLES 



OF FACE AND 



TONGUE) 



nucleus and septum pellucidum, while others are said to enter the caudate nucleus. 

 Posteriorly, it is continued into the roof of the inferior cornu of the lateral ventricle, 

 at the extremity of which it enters the nucleus amygdalae. Superficial to it is a 

 large vein, the terminal vein (vein of the corpus striatum), which receives numerous 

 tributaries from the corpus striatum and thalamus; it runs forward to the inter- 

 ventricular foramen and there joins with the vein of the choroid plexus to form 



the corresponding internal cerebral 

 vein. On the surface of the ter- 

 minal vein is a narrow white band, 

 named the lamina affixa. 



The Fornix (Figs. 720, 747, 748) 

 is a longitudinal, arch-shaped lam- 

 ella of white substance, situated 

 below the corpus callosum, and 

 continuous with it behind, but 

 separated from it in front by the 

 septum pellucidum. It may be 

 described as consisting of two 

 symmetrical bands, one for either 

 hemisphere. The two portions are 

 not united to each other in front 

 and behind, but their central parts 

 are joined together in the middle 

 line. The anterior parts are called 

 the columns of the fornix; the inter- 

 mediate united portions, the body; 

 and the posterior parts, the crura. 



The body (corpus fornicis) of the 

 fornix is triangular, narrow in front, 

 and broad behind. The medial part 

 of its upper surface is connected to 

 the septum pellucidum in front and 

 to the corpus callosum behind. The 

 lateral portion of this surface forms 

 part of the floor of the lateral ven- 

 tricle, and is covered by the ven- 

 tricular epithelium. Its lateral edge 

 overlaps the choroid plexus, and is 

 continuous with the epithelial cov- 

 ering of this structure. The under 

 surface rests upon the tela chori- 

 oidea of the third ventricle, which 

 separates it from the epithelial roof 

 of that cavity, and from the medial 

 portions of the upper surfaces of the 

 thalami. Below, the lateral portions 

 of the body of the fornix are joined 

 by a thin triangular lamina, named the psalterium (lyra). This lamina contains 

 some transverse fibers which connect the two hippocampi across the middle line 

 and constitute the hippocampal commissure. Between the psalterium and the corpus 

 callosum a horizontal cleft, the so-called ventricle of the fornix (ventricle of Verga), 

 is sometimes found. 



The columns (columna fornicis; anterior pillars; fornicolumns) of the fornix arch 

 downward in front of the interventricular foramen and behind the anterior commis- 



Fio. 746. Diagram of the tracts in the internal capsule. 

 Motor tract red. The sensory tract (blue) is not direct, but 

 formed of neurons receiving impulses from below in the thala- 

 mus and transmitting theni to the cortex. The optic radiation 

 (occipitothalamic) is shown in violet. 



