‘ ae ve 
578 THE NERVOUS SYSTEM. ~ , 4 
join the spinal accessory nerve in three situations :—(@) A branch from the second 
cervical nerve to the sterno-mastoid joins the spinal accessory nerve beneath that 
muscle. (b) Branches to the trapezius from the third and fourth nerves are con- 
nected with the spinal accessory nerve in the posterior triangle. (c) Branches from 
the same nerves join the spinal accessory nerve beneath the trupezius muscle. 
The internal branches of the plexus also comprise muscular and communi- 
cating branches. The first cervical nerve assists in the formation of this series of 
HyYPoGLOssAL NERVE VAGUS NERVE ; 
RECURRENT BRANCH | | Superior cervical ganglion of the sympathetic 
FIRST CERVICAL SE \ | 
\ 
SECOND CERVICAL NERVE 
Styloglossus 
Stylohyoid ligament 
Stylohyoid 
Superior constrictor 
| LINGUAL NERVE 
Tees iar es oy | - Ss : 
N = 
INN 
GLOSSO-PHARYNGEAL 
NERVE ~_ 
Stylopharyngeus ¥ 
— Hyoglossus 
Genio-hyoglossus 
PHARYNGEAL BRANCH OF VAGUS Nea 
Digastric —_“t___ 
\\ 
DESCENDENS HYPOGLOSSI Ws 
=; Genio-hyoid 
ate —— Mylo-hyoid (cut) 
\ ea Digastric 
(2 a Thyro-hyoid 
~ Sterno-hyoid 
z ih 
hi 
S 
Middle constrictor —\ 7 i 
DESCENDENS CERVICIS =. \ ; 
ee 
INTERNAL LARYNGEAL NERVE es 
ANSA vanes 
Inferior constrictor 
Omo-hyoid 
- Sterno-thyroid 
Omo-hyoid = ay ee 
Fic. 428.—THe Muscies oF THE Hyoip BONE AND STYLOID PROCESS, AND THE Extrinsic MUSCLES OF 
THE TONGUE, WITH THEIR NERVES. 
nerves, forming a slender loop with part of the second nerve in front of the trans- 
verse process of the atlas. 
Communicating Branches. («#) With the sympathetic—Gray vai communi- 
cantes pass to each of the first four cervical nerves, near their origins, from the 
superior cervical ganglion or from the cord below the ganglion. (b) With the 
pneumogastrie nerve-—The ganglion of the trunk of the pneumogastric nerve may 
be connected by a slender nerve with the loop between the first two cervical nerves. 
This communication is not constant. (¢) With the hypoglossal—An important 
communication occurs between the hypoglossal nerve and the loop between the first 
and second cervical nerves (Fig. 428). A trunk from the last-named nerves joins the 
hypoglossal just beyond its exit from the skull. One fine branch from this trunk 
passes upwards along the hypoglossal nerve towards the skull (meningeal branch). 
