THE CliANIAL OB ENCEPHALIC NERVES. 741 



number, and often join each other ; they may diviJed into (hree principal fasciculi rising 

 at slight distances. r r o 



The mutur roots are a little larger tl'an in tlie Horse ; before joining the sensitive roots 

 they are_ confounded m a small ganglion that pertains to them. 



The jugular ganglion is voluminous, but apart from this it presents the same features 

 as in the Horse, receiving all the proper roots of the pneuraogastric and internal root of 

 the spinal accessory, and even those wliioli are united iu their own ganglion. The 

 portion of the ganglion that is moie especially formed by the roots of the spinal aooessoiy 

 is rather an lutrication of nerve-fibres than a real ganj;lion ; it is impossible by the most 

 minute dissection to separate it fjom the rest of tiie ganglion. 



The jugular ganglion also receives a division of the glosso-pharyngeal, and it gives 

 one to this nerve and the external branch of the spinal accessory. 



The pneumogastric nerve, in the guttural portion, is much larger than in the Horse. 

 This peculiarity is noticeable throughout its whole extent, and is indicated at its 

 roots. 



• The ganglionic plexus is absent in the Ox. The course and relations of the nerve in 

 this portion are analogous to those observed in Solipeds. 



The pharyngeal nerve is voluminous, and the branch it sends to the oesophagus is the 

 largest of its divisions : this branch passes backwards to the surface of the constrictors 

 of the pharynx, joins the .external laryngeal, gives a large bianch to the thyro-pharyngeus, 

 ami is insinuated on the sides of the oesophagus, between it and the thyroid gland ; theie 

 it divides into two portions, one of which descends on the sides of the oesophagus where 

 it forms a very rich plexus with the branches from the inferior laryngeal, while the other 

 is lost immediately in the recmrent nerve at the thyroid gland. 



The external laryngeal arises at a short distance above the superior laryngeal, where 

 it receives a large branch from the glosso-pharyngeal and another from the sympathetic, 

 and immediately passes alongside the oesophageal branch of the pharyngeal nerve. 

 With a little attention, we may dissect a fasciculus coming from the external laryngeal 

 and passing to the crico-thyroid muscle, and the thyroid gland and its vessels, after receiv- 

 ing a branch from the superior laryngeal. In the Sheep, the external laryngeal sometimes 

 gives a branch to the oesophagus, and which anastomoses with the inferior laryngeal, or 

 descends on the side of the tube, conjointly with the cesopliageal branch of the 

 pharyngeal. 



The superior laryngeal rises below the preceding ; it is very voluminoiis, and com- 

 municates with the sympathetic, either directly or through the medium of the guttural 

 plexus, and with the pharyngeal nerves and external laryngeal. Benenth the thyroid 

 cartilage, a large division anastomoses with the inferior laryngeal, and is finally lost in 

 that nerve below the larynx. It is easily seen that this branch gives, in the cervical 

 region, a great number of filaments to the oesopha'.ius and trachea. 



With the exception of some insignificant prculiaiities, the pneumogastric compoits 

 itself iu the cervical and thoracic regions as in the Horse. 



The recurrents arise as in Solipeds, but their relalioiis are somewhat different in the 

 cervical region. They are placed in the channel formed by the trachea and ocfophagus, 

 and are separated from the carotid artery and the cord common to the sympathetic and 

 pneumogastiio by the very great width of the oesophagus. Their distribution to the 

 muscles of the larynx takes place as in the Hoise ; ihe only noteworthy feature is the 

 anastomosis of the nerve, end to end, with the superior laryngeal. In the whole of its 

 cervical portion, the branches to the oesophagus are more numerous and voluminous than 

 in Solipeds, although they all have the same physiologieal office, except those that are 

 derived from the branch of the superior laryngeal, which are motor. 



The diiferences remarked in tlie nerve in the abdominal cavity, are in relation to 

 the volume and form of the stomach and its compartments. 

 The following is what we have observed in the Sheep : 



After receiving a large filament from the superior cord, the mferior (esophageal nerve 

 divides into three principal branches : one passes to the left, furnishing nerves to the 

 anterior face and greater curvature of the reticulum and the upper border of the rumen ; 

 a median which is distributed to the anterior face of the psalterium, reaches the substance 

 of the mesentery follows the abomasum, to which it sends some filaments, and finally 

 anastomoses with the retrograde nerves coming from a rich plexus that exists on the 

 posterior face of the liver and gall-bladder ; it forms, conjomlly with the divisions of the 



pathetic and cervical ganglion ; 5, Pharyngeal nerve ; 6, External laryngeal ; 7, Superior 

 laryngeal ; 8, Inferior laryngeal ; 9, 9, (Esophageal branches of the pharyngeal and ex- 

 ternal laryngeal. 



50 



