630 



DISSECTION OF DEEP VESSELS AND NERVES OF NECK. 



and meniu- 

 geal. 



Directions 

 concerning 

 small 



branches of 

 the nerves. 



Dissection 

 to open 

 jugular 

 foramen. 



Follow 



spinal 



accessory 



and 



pneumo- 



gastric ; 



afterwards 



glosso- 



pharyngeal 



and its 

 branches. 



branch is sometimes large and furnishes the inferior palatine artery 

 instead of the facial. 



c. Small meningeal branches enter the skull through the foramen 

 lacerum, the jugular foramen and the anterior condylar foramen. 

 These arteries are seldom injected. 



The pharyngeal veins form a plexus which empties itself into the< 

 internal jugular trunk. 



Dissection of the cranial nerves in the neck. By the time, 

 this stage of the dissection has been arrived at, the condition of the 

 parts will not permit the tracing of the very minute filaments of the 

 cranial nerves in the jugular foramen, and the parts described in the 

 paragraphs marked with an asterisk cannot be seen at present. After- 

 wards, if a fresh piece of the skull can be obtained, in which the 

 bone has been softened by acid and the nerves hardened in spirit. 

 the examination of the branches marked thus * may be made. 



* In the jugular foramen. Supposing the dissection of the 

 internal carotid to be carried out as it is described at page 682, let 

 the student cut across with care the jugular vein near the skull. 

 Let him then remove bit by bit with the bone forceps, or with a 

 scalpel if the part has been softened, the ring of bone which bounds 

 externally the jugular foramen, proceeding as far forwards as the 

 osseous crest between that foramen and the carotid canal. Between 

 the bone and the coat of the jugular vein, the small auricular branch 

 of the pneumo-gastric nerve is to be found ; it is directed backwards 

 to an aperture near the styloid process. 



* Trace then the spinal accessory and pneumo-gastric nerves 

 through the foramen, by opening the fibrous sheath around them. 

 Two parts, large and small, of the spinal accessory nerve should be 

 defined ; the latter is to be shown joining a ganglion on the vagus, 

 and applying itself to the trunk of that nerve. A communication 

 between the two pieces of the spinal accessory is to be found. On 

 the prieumo -gastric is a small well-marked ganglion (ganglion of the 

 root], from which the auricular branch before referred to takes 

 origin ; and from the ganglion filaments are to be sought passing to 

 the smaller portion of the spinal accessory nerve, and to the ascending 

 branch of the upper cervical ganglion of the sympathetic. 



* Next follow the glosso-pharyngeal nerve through the fore part 

 of the foramen, and take away any bone that overhangs it. This 

 nerve presents two ganglia as it passes from the skull (fig. 226, p. 633) ; 

 one (jugular), which is scarcely to be perceived, near the upper part 

 of the tube of membrane containing it ; the other, much larger 

 (petrosal), is situate at the hinder border of the petrous portion of 

 the temporal bone. From the lower one, seek the small nerve of 

 Jacobson, which enters an aperture in the crest of bone between the 

 jugular foramen and the carotid canal, and another filament of com- 

 munication with the ganglion of the sympathetic. Sometimes the 

 dissector will be able to find a filament from the lower ganglion to 

 join the auricular branch of the pneumo-gastric, and another to end 

 in the ganglion of the root of the pneumo-gastric nerve. 



