58 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
extension of the sympathetic ramus is cephalad in the infraorbital — 
nerve. This is shown by the character of the cross section of the — 
nerve and by the direction of the fibers in the ganglion. The further 
anastomoses of nerves V and VII to form the infraorbital plexus offers _ 
opportunity for the wide distribution of this system throughout the 
head region. Practically every point of juncture in this complex is 
the seat of a larger or smaller group of sympathetic ganglion cells 
(Plate 2, fig. 4, el. gn. sy.). Except in the case of the infraorbital 
ganglion, none of those on the maxillary nerve is large enough to have 
been discovered by gross dissection without the aid of mounted pre- 
parations of dissected parts, a method which apparently has not been 
used by my predecessors. It is noticeable that, after the nerve is 
free from visceral connection, as in the ramus alveolaris superior, no 
more ganglia are found. 
Ill. Ramus mandibularis (md.). This is the largest of the tri- 
geminal branches, but, unlike the other two, it is not wholly afferent 
inits composition. It includes a certain number of motor components, 
‘which are given off to the mylo-hyoideus muscle. The mandibular 
ramus leaves the portio major of the Gasserian ganglion from its 
ventro-lateral side (Plate 3, figs. 6, 7), being covered dorsally by the 
ramus maxillaris. Its course to the lower jaw lies between the mm. 
pterygoideus and pterygo-sphenoidalis posterior. It crosses dorsal 
(lateral) to the pterygoquadrate process just behind the insertion of 
the m. pterygo-parietalis, passing through the deeper part of the 
pterygoideus to reach the median side of the mandible (Plates 5, 6, 
figs. 15-17). As it approaches the mandible two rami are given off 
together to be distributed to skin and muscle of this region. The 
continuation of the main nerve is known as the ramus alveolaris 
inferior (alv. if.). It still contains a few motor fibers for the mner- 
vation of the anterior part of the m. mylo-hyoideus. 
III, 1. The two branches above mentioned are given off from the 
main ramus at the point where the latter makes a turn cephalad to 
enter the mandible. They might be considered one branch which 
immediately divides into a posterior and an anterior ramus. The 
posterior ramus (md.') turns back (Plates 2, 3, figs. 5, 6) and crosses 
Meckel’s cartilage dorsally, reaching the lateral side of the mandible 
(Plate 6, fig. 16) through a foramen between the dentary and angu- — 
lare bones. It passes through the superficial throat muscles to the 
mylo-hyoideus muscle, a very small sensory twig passing on to the 
skin. Most of the fibers are motor, innervating a part of the mylo- 
hyoideus muscle (Fig. SY). 
