392 CHARLES CLIFFORD MACKLIN 



zontally, and thus differ from the earlier conditions, where they 

 are considerably higher laterally than medially (Jacoby). 



The dorsal root is the smaller, and is directed outward and 

 slightly upward. Thick and rounded in section, its cartilage 

 is directly continuous with that of the lamina hypochiasmatica, 

 from the side of which it has been seen to project. A short dis- 

 tance from its origin it widens out, and at the same time rises 

 cranially to form a plate, flattened from above downward, out- 

 ward and slightly forward, the dorsal edge of which presents, 

 near the median line, a backward projection, the anterior clinoid 

 process (fig. 3). Between this process and the edge of the 

 Balkenplatte, rendered more sharply defined on the right side 

 by the middle clinoid process, there is to be seen a distinct notch, 

 which lies dorsal to the root, opposite the most posterior extremity 

 of the optic foramen, and conveys the internal carotid artery. 

 The dorsal border of the wing, after leaving the anterior clinoid 

 process, passes upward, forward and outward, making a dorso- 

 lateral convexity, and finally turns abruptly backward upon 

 the dorso-lateral process. The ventral border of the root forms 

 the dorsal and part of the lateral border of the foramen opticum, 

 while its lower surface, together with that of the wing lateral to 

 it, forms the cranial delimitation of the superior orbital fissure. 



The ventral root is wide and flat, and is directed outward 

 and slightly backward. It is considerably the longer, as well 

 as the broader, and is directly attached to the dorsal border of 

 the interorbital septum along the line indicated in figure 11. 

 In addition it is connected, through the praechiasmatic com- 

 missure, with the ventro-lateral edge of the hypochiasmatic 

 lamina (fig. 1). The ventral root occupies a somewhat higher 

 level than the dorsal. The dorsal border curves outward and 

 backward, to assist in the delimitation of the foramen opticum; 

 the ventral border passes almost directly outward, and forms 

 the dorsal border of the orbitonasal fissure. Through the por- 

 tion of the wing lying lateral to the optic foramen it is continuous 

 with the dorsal root; and in this way is formed the shelving side 

 of a recess, the floor of which is made up of the .hypochiasmatic 



