ANATOMY IN A NUTSHELL. 



351 



ward from the anterior and lateral angles into the frontal lobes. The forceps 

 major are fibers which continue backward through the posterior angles into the 

 occipital lobe. 



LESSON CI. 



The septum lucidum forms the inner boundary of the lateral ventricle and 

 unites in front with the genu and rostrum of the corpus callosum. Posteriorly 

 and inferiorly it is united with the fornix and its anterior peduncles. (Plate 

 CLXXXIV). It consists of two laminae which enclose the fifth ventricle. It is 



PLATE CLXXI. 



LATERAL SINUS 



A Coronal Section Through the Posterior Horns of Lateral Ventricles. 



a triangular area of gray matter. This ventricle was originally a part of the 

 great longitudinal fissure but the two hemispheres are united above by the cor- 

 pus callosum and below by the fornix, and the space betwe< ;> them becames a 

 distinct cavity with walls of its own — lamina 1 or septum Lucidum. The Loner 

 layer is gray, middle white, and external one ependymal or ependyml tissue 

 covered by the epithelial layer continuous with that lining the lateral ventricle. 

 Velum interpositum or tela choroidea superior the word tela means a web 

 and is applied to a membrane formed by the position of the pia mater and 

 ependyma when the intervening layer of nerve tissue has disappeared. It is 

 a triangular process of pia mater which is prolonged through the transverse 

 fissure and lies over the third ventricle and upper surface of the op1 ic thalamus. 

 from its under surface it supplies two vascular processes which form the 



