244 
(i) 
(1) 

Fic. 79. Plan of 
ANATOMY OF THE RABBIT. 
The twelfth cranial or hypoglossal nerve (n. hypo- 
glossus) enters the base of the tongue. It lies on the lateral 
side of the external carotid artery and on the medial side of 
the stylohyoideus major. It is distributed as a motor nerve 
to the lingual muscles. 
The ramus lingualis of the ninth cranial, or glosso- 
pharyngeal nerve (n. glossopharyngeus) enters the base of 
the tongue at a point dorsal to the hypoglossus and between 
the stylohyoideus minor and the stylo- 
pharyngeus. 
the tongue. 
8. Dissection of the extra-cranial roots. of 
the ninth to twelfth nerves (Fig. 79). 
These nerves, which for the most part have 
already been exposed, may be traced to their 
origin in the jugular and hypoglossal foramina. 
The tympanic bulla should be cleared and 
the tendons of origin of tongue muscles 
removed from the jugular process. 
(a) The ninth (glossopharyngeal) nerve 
It isa gustatory nerve of 
the 
extra-cranial roots of the 
IX-XII cranial nerves and 
sympathetic trunk; ventral 
surface, right side, the 
sympathetic and depressor 
nerve shown as displaced 
from the dorsal surface of 
the’ ‘artery.5-9) (LO; br, 12; 
glossopharyngeal, vagus, 
spinal accessory, and hypo- 
glossal nerves; ac, carotid 
artery; c, cervical root of 
ramus descendens XII; 
gn, ganglion nodosum vagi; 
(b) 
is farthest forward. Its two main 
branches are the ramus lingualis to 
the tongue, and the ramus pharyn- 
geus, the latter entering the lateral 
wall of the pharynx. 
The tenth (vagus) nerve bears an 
elongated ganglionic enlargement, the 
ls, superior laryngeal; 
depressor nerve; rd, ramus 
descendens hypoglossi;_ s, 
sympathetic. 
ee plexus ganglioformis (ganglion 
nodosum). It lies immediately below 
the jugular foramen. 
The superior laryngeal nerve and the ramus cardiacus 
(depressor nerve) are given off at the level of the origin of the 
internal carotid artery. 
The eleventh cranial, or spinal accessory nerve (n. 
accessorius) is dorsal to the vagus. The nerve passes dorsad 
to the medial side of the mastoid attachments of the sterno- 
hyoideus and cleidomastoideus muscles, giving branches 
to the latter, and then passes backward to the ventral surface 
of the trapezius to which it is distributed. 
