110 DISSECTION OF THE NECK. 



Pharyngeal branches. Other small arteries ramify in the upper con- 

 strictor, the Eustachian tube, the back of the soft palate, and the tonsil. 



The vein accompanying the pharyngeal artery receives branches from the 

 cranium, the palate, and the pharynx, and ends in the internal jugular vein. 



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 per- 

 mit the tracing of th.e very minute filaments of the cranial nerves in the 

 foramen jugulare of the skull ; and all the paragraphs marked with an 

 a-sterisk are therefore to be omitted for the present. Afterwards, 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 

 now passed over may be made. 



* In the foramen lacerum (fig. 26). Supposing the dissection of the 

 internal carotid to be carried out as is described at page 107, let the stu- 

 dent 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 fora- 

 men, 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 pneumogastric nerve is to be found; it is 

 directed backwards to an aperture near the styloid process. 



* Trace, then, the spinal accessory and pneumogastric nerves through 

 the aperture, 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 parts of 

 the spinal accessory is to be found. On the pneumogastric is a small well- 

 marked ganglion, from which the auricular brancli 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. 2G): one (jugular), which is 

 scarcely to be perceived, near the upper part of the tube of membrane 

 containing it; the other, much larger (petrous), is situate at the lower 

 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 communication with the ganglion of the sympathetic. Some- 

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

 to join the auricular branch of the pneumogastric ; and another to end in 

 the upper ganglion of the pneumogastric nerve. 



Below the foramen of exit from the skull the cranial nerves have been 

 greatly denuded by the dissection of the internal carotid (fig. 25) ; but 

 the intercommunications of the vagus, hypoglossal, sympathetic, and first 

 two spinal nerves near the skull, are to be traced out more completely. 



The larger part of the spjnal accessory has been sufficiently laid bare 

 already; but its small piece is to be traced to the vagus, close to the skull, 

 and onwards by the side of that trunk. 



The chief part of the glosso-pharyngeal has been also dissected ; but the 

 offsets on the carotid, and others to join the pharyngeal branch of the 

 vagus and the pharyngeal plexus are to be displayed. 



