CoGHiLL, Cranial Nerves of Ambly stoma. 211 



less detail. The specimens used for this purpose were larvae 

 of approximately the same size, about four and one-half inches 

 long. 



Case A. — From its foramen laterad, the oculomotor nerve 

 follows a course approximately parallel with the optic nerve. 

 As it approaches the r. ophthalmicus profundus V, the oculo- 

 motor divides into its superior and inferior branches. 



The superior ramus passes dorsally of the r. ophthalmicus 

 profundus, and following for some distance the mesial aspect of 

 the m. rectus superior, innervates this muscle. But just at the 

 point where the nerve begins to ramify into the muscle it comes 

 into very close relation with a twig from the r. ophthalmicus. 

 The trigeminal twig penetrates the m. rectus superior from the 

 mesial side and comes to lie along the lateral and superior sur- 

 face of the muscle. This case alone would indicate a possi- 

 bility of an anastomosis between these two nerves at this point. 



The inferior ramus of the oculomotor continues the course 

 of the main nerve distally in a position ventral of ophthalmicus 

 profundus and dorsal of the m. rectus internus. It then pene- 

 trates the m. rectus inferior from the dorsal to the ventral side. 

 At the ventral margin of the muscle it sends one twig dorsad 

 to the m. rectus internus which it innervates, and another twig 

 latero-cephalad to supply m. obliquus inferior. 



As the inferior ramus of the oculomotor approaches the 

 superior surface of the m. rectus inferior in the manner just 

 described, it comes in contact with the inferior ciliary nerve of 

 the ophthalmicus profundus. There are no ganglion cells visi- 

 ble at this point, and the greater part, if not all, of the ciliary 

 nerve separates from the oculomotorius as the latter penetrates 

 the muscle. 



Case B. — The third nerve turns cephalad from its foramen 

 closely compressed between the temporalis muscle and the lat- 

 eral cranial wall. In this position it lies parallel with the ten- 

 don of the mm. recti inferior and internus, and dorsally of the 

 tendon. As the muscles arise from this tendon the nerve 

 comes to lie mesially of them and divides into the inferior and 

 superior rami. 



