846 THE NERVES. 



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

 by the very great widtli of the oesophagus. Their distribution to the muscles of the larynx 

 takes place as in the Horse; the only noteworthy feature is the anastomosis of the nerve, end 

 to end, witii the superior laryngeal. In tlie whole of its cervical poition, the branches to the 

 oesophagus are more numerous and voluminous than in Solipeds, although they all have the 

 same physiological oflSce, except those that are derived from the branch of the superior laryngeal, 

 which are motor. 



The differences remarked in the 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 inferior oesophageal 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, conjointly with the divisions of the solar plexus and superior 

 cesnphageal nerve, a rich plexus, from which arise branches to the liver, abomasum, and 

 duodenum. 



The superior (xaophageal nerve is chiefly distributed to the rumen. Before reaching the 

 stomach, it gives several divisions to the plexus already mentioned — and which might be 

 named the " hepatic plexus" — receives a large branch from the solar plexus, and sends to it a. 

 smaller one. It afterwards divides into two principal bratiches, the largest of which passes 

 along the superior fissure of the rumen, along with the vessels of that organ. According to 

 Lavocat, this branch forms a large plexus there, which has in its centre a ganglionic enlarge- 

 ment, whence emanate the ramuscules that go to the whole of the upper face, sides, and lower 

 surface of the rumen. In the Sheep we have not found a ganglion, but this does not prevent 

 this branch from being distributed to all the parts indicated by Lavocat. 



The other branch is very large, and situated in the omentum until it arrives at its convex 

 border, when it leaves it to be distributed to the left side of t; e abomasum ; while the analo- 

 gous nerve from the inferior oesophageal passes more especially to the right face. 



In the Camel, the pneumogastric gives off, near tlie point where it joins the cervical 

 branch of the sympathetic, a very remarkable branch. This is somewhat plexiform at ita 

 origin, and directly furnishes a certain number of pharyngeal filaments, the superior laryngeal 

 nerve, and, a little lower, the inferior laryngeal nerve, forming a slight arch where it curves to 

 ascend; it then descends along the oesophagus into the thorax, giving filaments to that tube 

 and to the trachea. When it reaches the second dorsal vertebrae, this branch unites, below 

 the oesophagus, with that of the opposite side. The single branch resulting from this union 

 runs between the trachea and oesophagus, and ends by dividing into several filaments that 

 enter the bronchial plexus. 



For the whole of its cervical course, the pneumogastic lies close beside the sympathetic 

 and does not give off any ramuscles worthy of note. After separating from the sympathetic 

 at the entrance to the chest, it passes into that cavity alongside the trachea to the commence- 

 ment of the bronchi ; there it forms, with its congener of the opposite side, the broncho- cesopha- 

 geal plexus, which is extremely remarkable, and is prolonged behind by the oesophageal nerves 

 — similar to those in the Horse. The pneumogastric does not appear to directly furnish 

 filaments to the inferior cervical ganglion. 



Spinal accessory. — The origin of this nerve offers sliglit differences, which we have indicated 

 in speaking of the motor roots of the pneumogastric. With regard to its distribution in the 

 Ox, it offers the following features : At the inferior extremity of the transverse proce.'ss of the 

 atlas, it divides into two branches — a superior and inferior. The first is a little larger than 

 the spinal accessory of the Horse, and comports itself as in that animal. The infi rior branch 

 is directed downward and backward, traverses the muscle we have named the sterno-sub- 

 occipital (see Myology), beneath a tendon that runs across the muscular fibres, and arrives 

 Letween that muscle and the sterno-maxillaris. At this point it separates into a certain 

 number of ramuscules, the fir.st three or four of which are slightly recurrent, and enter the 

 upper part of the sterno-maxillaris ; the others are large and directed towards the sternum, 

 to be distributed to the latter muscle, or to it and the sterno-suboccipitalis. 



These branches ot the spinal accessory represent the branch which, in the Horse, ]>asses 

 exclusively to the sterno-maxillaris. In retiectinij on the distiibution they offer in the Ox, we 

 are brought to the conclusion tiiat the sternnl hand, which has been descrilied as belonging to 

 the first, forms, with the sterno-suboccipitalis. one and the sace muscle — the analogue of the 



