112 LABORATORY OUTLINE OF NEUROLOGY 



carefully, cutting from the ventricle directly outward through the 

 wall of the hemisphere to the brain surface, and must follow 

 the border of the hippocampus closely. It will curve around 

 from the ventral to the medial surface of the hemisphere and 

 finally pass through the splenium of the corpus callosum into 

 the septum pellucidum. Remove the septum pellucidum and 

 review the form of the entire hippocampal formation, including 

 the gyrus dentatus, fimbria, and corpus fornicis. The floor of 

 the inferior horn of the lateral ventricle is formed in part by the 

 hippocampus and fimbria and in part by the membranous 

 plexus chorioideus of the lateral ventricle. Note that this 

 membrane has two lines of attachment to the massive brain 

 walls, one to the free border of the fimbria (the taenia fornicis) , 

 and one to the brain stem along the line of contact between the 

 corpus striatum and thalamus (the taenia chorioidea) . Between 

 these two lines the membrane is folded into the ventricle, thus 

 forming the fissura chorioidea. See the references cited in 

 Section 130. 



Now repeat on the human the directions outlined for the sheep 

 in Sections 128 and 129. 



143. Stria terminalis. — The human brain, following the pro- 

 cedure outlined in Section 132, may be further dissected as 

 follows: 



Look into the lateral ventricle, as already exposed, and locate 

 the head of the caudate nucleus in the floor of the lateral ven- 

 tricle above the anterior commissure. Now trace the tail 

 (cauda) of the caudate nucleus backward into the inferior horn 

 of the lateral ventricle where it ends in the vicinity of the nucleus 

 amygdala. Also follow the stria terminalis (stria or taenia 

 semicircularis), which accompanies the ventral border of the 

 caudate nucleus for its entire length. Some of its fibers can 

 be seen to enter the anterior commissure. This stria is a cor- 

 relation tract between the nucleus amygdala and the medial 

 olfactory area of the same and the opposite side. It marks 

 the boundary between the cerebral hemisphere and the thalamus. 



144. Corpus striatum. — Remove the hippocampus. Now 

 pull upward on the corpus callosum and upper wall of the 

 lateral ventricle so as to rip off the entire roof of the ventricle, 

 tearing it free from the upper (lateral) border of the caudate 



