1888. ] 101 (Stowell. 
sorius, hypoglossus and sympathic nerves. Peripherad of the plexus the 
N. hypoglossus bends abruptly around the caudal border of the A. occi- 
pitalis (Fig. Ang.) and crosses the ectal surface of the N. vagus just 
cephalad of the G. inferius (vagus), also crosses the ectal surface of the 
A. carotidea and lies upon the ectal surface of the A. lingualis, which 
it crosses twice (the artery being the more sinuous), first about 8 mm. 
peripherad of the origin of the artery (A. lingualis), and again 10-12 mm. 
still peripherad. This portion of the trunk lies entad of the M. stylo- 
hyoideus, along the caudal border of the M. digastricus. 
Communicating Rami of the Trunk.—At the angle (Fig. Ang.) a con- 
siderable accession is received from the first cervical nerve (myelic, Fig. 
Anas.) ; it is possible that this accession is the true origin of the cervico- 
hypoglossal nerve. (The minute anatomy of this region has not been 
satisfactorily determined.) Just cephalad of the G. inferius, and per- 
ipherad of the plexus a large ramus (Fig. Inf.) joins the ganglion at 
its dorso-cephalic border. 
PRINCIPAL RAMI. 
N. cervico-hypoglossus; N. cervicalis descendens ; N. descendens 
noni.—At the angle (Fig. Ang.) where the accession is received from 
the myelic nerves, as the hypoglossus curves around the A. occipitalis, 
the N. cervico-hypoglossus takes its ectal origin. An anastomotic nerve 
joins the myelic nerve and this trunk (Fig. Anas.). The existence of 
this anastomosis makes it debatable whether the cervico-hypoglossus 
should be considered a ramus of the N. hypoglossus having a myelic 
accession, or a myelic nerve having a large accession from the N. hypo- 
glossus. Ihave adopted the compound name applicable to either of the 
views cited. 
The course of the nerve is ventro-caudad, and is at first entad of the 
jugular vein ; it reaches the carotid artery about 7 mm. caudad of the 
A. occipitalis and continues caudad upon the ectal surface of the artery 
about 12 mm. to the origin of the A. thyroidea. 
N. omo-hyoideus.—At the origin of the A. thyroidea, a large ramus 
is given off ventrad (Fig. Om-Hy. ce.). This ramus lies ectad of the 
artery and innerves the cephalic 25 mm. of the M. omo-hyoideus. The 
caudal portion of the muscle is innerved by a ramus of the N. cervico- 
hypoglossus which takes its ectal origin at the point where the nerve 
trunk touches the dorsal border of the M. sterno-thyroideus. This slen- 
der caudal ramus crosses the ectal surface of the sterno-thyroid muscle, 
enters its dorsal border and may be traced within the muscle to the pre- 
Sternum* (Fig. Om-Hy. ca.). 
N. sterno-thyroideus.—-Caudad of the A. thyroidea the cervico-hypoglos- 
Sus lies in the ental cervical fascia, ectad and ventrad of the A. carotidea. 
* The origin of the M. omo-hyoideus is costal instead of scapular, as is the case in 
man; the general relations are such that little doubt can exist as to the homology of the 
muscle, 
