WILLARD: CRANIAL NERVES OF ANOLIS CAROLINENSIS. 45 
K. TROCHLEAR NERVE. 
Nerve IV (Plate 2, fig. 4, JV), from its nucleus of origin on the side 
of the aqueduct floor opposite to that of its emergence, passes dorsad 
of the mesocoele directly to the surface, the whole central course 
showing in a single transverse section. Peripherally it turns cephalad 
for a short intracranial course, lying between the brain and the Gas- 
serian ganglion. It then passes through the membranous cranium, 
but keeps a median position throughout its course, to the dorsal oblique 
muscle, which receives all of its fibers (Plates 5, 6, figs. 12-17). 
L. ABDUCENT NERVE. 
The central origin of nerve VI (Plate 2, fig. 4, VZ) in the meten- 
cephalon was readily found. The neuraxons leave this part of the 
brain in small groups as large heavily medullated fibers. These 
emerge from the ventral side of the brain in small rootlets, which 
immediately combine into one main trunk. After a short intra- 
cranial course nerve VI enters the sphenoid bone and takes a 
course cephalad through a special foramen between the outer and 
inner lamellae of this bone, and dorsal'to the beginnings of the basi- 
pterygoid process of the sphenoid (Plate 6, fig. 17). This foramen 
opens mesally into the bony pocket protecting the ventral end of the 
pituitary body and at the point of origin of the bursalis and retractor 
oculi muscles. Nerve VI passes through these muscles to reach the 
posterior rectus, which it innervates (Plate 5, 6, figs. 15, 16). The 
bursalis and retractor oculi muscles are innervated by a small ramus of 
not more than 25 fibers which is given off from VI as it passes between 
chem. This is shown in Plate 6, fig. 16 (brs.), but in the plotting 
Plate 2, fig. 4) it is covered by the main trunk. It is difficult to 
xplain the very pronounced disproportion between this small ramus 
nd the remainder of the abducent nerve. No connection was found 
vhich would relate the abducent nerve to any structures other than 
he three muscles named. 
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In their macroscopic features the ciliary nerves and ganglion and 
\eir relation to the trigeminal and oculo motor nerves are compara- 
CILIARY GANGLION AND NERVES. 
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