MUSTELDS L^VIS. 161 



the ganglionic complex from which the buccalis arises forms 

 a distinctly separate ganglion^ which lies partly embedded in 

 the underlying antero-ventral part of the entire complex. 

 Both nerves, forming a single trunk, run at first laterally, 

 forward, and downward, the truncus maxillo-mandibularis 

 separating immediately into two strands, one of which is the 

 ramus raaxillaris trigemini, and the other the ramus maudi- 

 bularis trigemini. The ramus mandibularis immediately 

 passes laterally and forward, ventral to the buccalis, and thus 

 soon acquires a position postero-latei-al, and in part ventral 

 to the latter nerve. The ramus maxillaris remains along the 

 autero-mesial edge of the buccalis, also lying in part ventral 

 to it, the buccalis forming, in sections, a large blunt wedge 

 between the two trigeminal nerves. The three nerves 

 together here form a single large and flattened trunk, which 

 lies on the dorsal surface of the so-called basal plate of the 

 skull, which plate, projecting laterally and somewhat down- 

 ward, forms the floor of the orbit. The nerve trunk lies 

 immediately internal to the large peri-orbital sinus, and in 

 its forward course it passes internal, or ventral, to all the 

 structures in the orbit, excepting only to two arteries, the 

 anterior and posterior carotids of Parker's descriptions. It 

 passes dorsal to the anterior carotid, immediately postero- 

 lateral to the point where its ophthalmic branch is given off, 

 and then lies antero-lateral to the artery. The posterior 

 carotid pierces the floor of the orbit, and passes from its 

 ventral to its dorsal surface, ventral to the hind end of the 

 extra-cranial trigemino-facial ganglion. It then reaches the 

 lateral aspect of the ganglion, and as it traverses the orbit, 

 running forward and laterally, lies ventral to the lateral edge 

 of the truncus buccalis-maxillo-mandibularis, the truncus 

 thus lying dorsal to the artery. 



In this orbital part of the course of the truncus the 

 buccalis is, as already stated, a somewhat triangular strand 

 wedged in between the mandibularis and maxillaris. Soon 

 after the truncus leaves its ganglion, certain general sensory 

 branches arise from the ramus maxillaris, and run outward 



