Stowell.] 102 [March 2, 
At a point opposite the cephalic extremity of the thyroid body, the nerve- 
trunk sendsa slender ramus, the cephalic sterno-thyroid (Fig. St.-Thy. ce), 
to the cephalic third of the M. sterno-thyroideus : the caudal ramus (Fig. 
St.-Thy. ca.) is the caudal 50-60 mm. of the N. cervico-hypoglossus, and 
may be said to have its ectal origin at the origin of the ramus to the cau- 
dal portion of the M. omo-hyoideus or at the point where the nerve trunk 
lies upon the dorsal border of the sterno-thyroid muscle ; it follows the 
border of the muscle for about 20-30 mm., when it penetrates the muscle 
and terminates within the caudal extremities (origins) of the muscles 
(sterno-hyoid, omo-hyoid, sterno-thyroid), which have a common origin 
from the lateral border of the preesternum and the first costal cartilage. 
Opposite the caudal extremity of the thyroid body the cervico-hypoglos- 
sal nerve is joined by a communicating ramus (Fig. communicans) from 
the adjacent cervical plexus or loop. This is the N. communicans noni. 
This branch does not seem to be constant. 
N. thyro-hyoideus.-—The ectal origin of this ramus is entad of the V. 
jugularis, immediately peripherad of the origin of the cervico-hypoglossal 
nerve ; its course is parallel to the latter nerve and ventrad of it ; it crosses 
the ectal surface of the A. carotidea at the origin of the A. laryngea ceph- 
alica, whence it bends ventrad and lies caudad of the artery and cephalad 
of the N. laryngeus internus; it innerves the M. thyro-hyoideus (Fig. 
Thy.-Hy.) and sends two terminal ramuli to the M. sterno-hyoideus, 
a cephalic ramulus to the cephalic portion, a cawdal one to the caudal por- 
tion of the muscle. This nerve joins its platetrope in the ventri-meson. 
N. stylo-glossus._-A bout 15 mm. ventrad of the A. carotidea the A. 
lingualis gives an arteriole to the M. stylo-glossus ; centrad of this arteri- 
ole the hypoglossus nerve sends a branch, the N. stylo-glossus, to the 
muscle having the same name. The nerve lies upon the ectal surface of 
the M. hyo-glossus; at the ventral border of the stylo-glossus muscle it 
separates into a leash of terminal ramuli which intercommunicate by anas- 
tomotic filaments upon the muscle (Fig. Sty.-Gloss.). 
N. hyo-glossus.—5 mm. peripherad of the last nerve the hyo-glossal 
nerve (sometimes 8-4 ramuli from a common trunk, or more frequently 
separate nerves) is given to the fibres of the M. hyo-glossus. The nerve 
crosses the ectal surface of the A. lingualis. The terminal filaments inter- 
communicate and form a loose plexus (Fig. hyoglossus) with the N. lin- 
gualis (R. of N. trigeminus), which in this region lies upon the ectal sur- 
face of the ranine artery. 
N, genio-hyoideus.—At the dorsal border of the M. genio-hyoideus, the 
N. hypoglossus curves cephalad and follows the general direction of the 
genio-hyoid muscle, to which it gives from its ventral border the N. genio- 
hyoideus, which nerve may be traced 20 mm. cephalad in the muscle 
(Fig. Gen.-Hyoid). 
N. genio-hyo-glossus.—-Peripherad of the border of the M. genio-hyoid- 
eus, the N. hypoglossus bends mesad around the A, lingualis and lies 
entad of the artery. As it curves around the artery it gives from its ven- 
