Henry L. Bruner 47 
In Phrynosoma and in all forms in which the muscle has a single 
attachment, the m. constrictor vene jugularis interne acts merely as ¢ 
constrictor of the jugular vein. In Lacerta, on the other hand, the 
muscle not only obstructs the vein but also changes the position of the 
epibranchial cartilage, which is moved through a small are about its 
fixed anterior end. This fact explains the oblique direction of the fibers 
which insert on the cartilage (compare Text Fig. 7), their course being 
parallel with the are described by the crista epibranchialis. This second 
function does not seem to impair the efficiency of the muscle as a con- 
strictor, for the fibers which insert on the epibranchial cartilage form a 
closed ring, and owing to the movability of the cartilage, they still act 
as an effective constrictor of the vein. 
2. INNERVATION OF THE M. CONSTRICTOR VEN JUGULARIS INTERN. 
—Before describing the innervation of the m. constrictor ven jugularis 
interne of Lacerta, I must call attention to the following nerves which 
lie in close proximity to the muscle: 
(1) Ramus communicans internus n. glossopharynget cum n. faci- 
ali (ramus communicans internus rami palatini cum n. glossopharyngeo 
of Fischer, 52).—This nerve (r. c. 1., Text Figs. 2 and 7; Fig. 3; Plate I) 
arises from the ganglion glossopharyngei (ganglion petrosum of authors) 
and runs forward on the median side of the vena jugularis interna. It 
passes under or through the median attached portion of the constrictor 
muscle, then between the epibranchial cartilage and the pratympanic 
furrow, and eventually joins the ramus palatinus VII near its origin 
from the ganglion facialis. 
(2) Ramus communicans externus n. glossopharynget cum n. faci- 
ali (ramus communicans externus n. facials cum n. glossopharyngeo of 
Fischer, 52).—This nerve (r. c. e., Text Figs. 2 and 7; Figs. 3, Plate I) 
begins at the ganglion glossopharyngei and runs forward on the dorsal 
aspect of the ramus internus. It passes through or immediately above 
the median attached portion of the constrictor muscle, anterior to which 
it bends laterad under the jugular vein and enters the sheath of the 
ramus posterior VII. A part of its fibers join the latter nerve, but not 
all; about one-half of the fibers emerge from the nerve laterally and join 
the ramus communicans n. glossopharyngei cum n. maxillari, as de- 
scribed below. 
The rami communicantes n. glossopharyngei cum n. faciali are some- 
times united for a short distance anterior to the ganglion glosso- 
pharyngei. 
