378 P. R. BILLINGSLEY AND 8S. W. RANSON 
TABLE 6 
Branch to the superior thyroid artery 
pl N a a NUMBER OF fone ae DIAMETERS OF MYELINATED FIBERS 
MILLIMETERS MILLIMETER 1.5 to 33h 3.3 to 6.6 wu 6.6% plus 
per cent per cent per cent 
VI 0.0044 28 6238.25 78.5 21.5 ‘ 
VII 0.0128 45 3503.5 84.5 15.5 
VIII 0.004 67 16709.0 100.0 ‘ 
IX 0.0069 42 6076.0 95.0 2.5m 2.5 
x 0.0059 14 2303.0 28.5 50.0 21.5 
branch terminates in the plexuses about the lingual and facial 
arteries. 
On the whole, the myelinated fibers in the branch to the supe- 
rior thyroid artery do not differ materially from those in the other 
nerves studied. The number per square millimeter shows great 
variation and the majority of the fibers do not exceed 3.3y in 
diameter. But larger fibers are also found, and in one case 21 
per cent measured more than 6.6u. 
BRANCHES TO THE EXTERNAL CAROTID ARTERY (NN. CAROTICI 
EXTERNIT) 
In all but two cases the external carotid plexus was seen to be 
formed by two large branches from about the middle of the 
medial side of the ganglion (13 and 14), which ran upward and 
slightly medialward to the bifurcation of the common carotid 
artery. These branches commonly pass medial to the internal 
carotid artery, but in one case they passed to either side of the 
artery and then joined. At the bifurcation of the common 
carotid they communicate by small twigs with the carotid body 
and then at once form a rich plexus of fibers which is spread outt, 
upon the external carotid artery. At the point of communica- 
tion with the carotid body several minute twigs can be traced to 
the region of the pharynx. 
In two eats, Nos. VIII and X, only one branch was found, in 
the others the two branches were treated as one in making up 
table 7. The area given in that table is the sum of their areas, 
