744 THE NERVES. 



On the left side the same arrangement is found ; the anastomoses are larger and more 

 numerous than on the right side ; the branch follows, in an inverse direction, the course 

 pursued by the recurrent nerve, to join the pneumogastric at the part where the recurrent 

 originates from the latter. 



In this course, the branch gives large ramuscules to the oesophagus and trachea ; 

 those distributed to the former either pass along the muscular tunic and return again to 

 the nerve, or continue along the surface of that tube. In all cases, there is found on the 

 sides of the oesophagus a rich plexus formed by these filaments, as well as by those 

 coming from the pharyngeal nerve. 



This branch also offers other peculiarities. Thus, it is very often found alongside the 

 laryngeal nerve for some distance, and sometimes at several points. When this happens 

 in the upper part, at the larynx, as occurs in many cases, it appears to have an anasto- 

 mosis as in the Ox ; but it is always easy to separate the two nerves, even in fresh 

 specimens, and this separation is greatly facilitated if the piece has been steeped in 

 water acidulated by nitric acid. 



In the cervical portion, the pneumogastric nerve is closely united to the sympathetic, 

 the separation of the nerves being no longer possible as in the Horse and Ox. 



We have already described a portion of the inferior laryngeal nerve, in speaking of 

 the tracheo-oesophageal branch of the superior laryngeal. Comparison with other 

 animals requires that we should transfer the latter to the recurrent. In the Dog, the 

 inferior laryngeal rises by two distinct branches, a short distance from each other, on the 

 right and left sides ; these may, or may not, lie together for some distance, but they never 

 become fused. The external part of the nerve receives at intervals filaments proceeding 

 from the superior laryngeal branch, and it rarely gives very fine twigs to the trachea 

 and oesophagus. The communications with the cardiac and tracheal nerves are also 

 chiefly made by the tracheo-oesophageal branch. 



The bronchial nerves are large and numerous. 



The cesophageal plexus, which is furnished by the nerves of the same name, is larger 

 and finer than in the Horse. 



There is nothing to note particularly in the termination of the nerves in the 

 stomach. 



The hypoglossal gives a long branch that passes to the sides of the larynx, and enters 

 the muscles on the anterior face of the trachea. 



COMPARISON OF THE CRANIAL NERVES OF MAN WITH THOSE OF ANIMALS. 



The few modifications offered by the cranial nerves of Man, when compared with 

 those of animals, are dictated by the disposition of the parts and organs to which they 

 are distributed. 



We have spoken of the olfactory lobe* when studying the brain, so that we need not 

 again refer to them. The three succeeding nerves offer nothing worthy of mention. 



Trigeminal nerve. This has the same origin and divisions as in animals. 



The frontal nerve of the ophthalmic portion divides into two branches ; these are 

 inflected upwards on the margin of the orbit, and distributed to the skin of the forehead. 

 These two branches, well developed in the Dog, are distinguished as internal and 

 external. The latter anastomoses with a branch of the facial. The nasal nerve, after 

 spreading over the surface of the turbinated bones and the meatus, gives off a ramuscule 

 that becomes subcutaneous in passing between the inferior border of the nasal bone 

 and cartilage of the nostril ; this is the naso-lobular nerve. 



The superior maxillary nerve leaves the cranium by the foramen rotundum, reaches 

 the suborbital furrow, and spreads over the face by suborbital branches. Like that of 

 animals, it gives rise to an orbital ramuscule, and posterior and anterior dental branches. 

 Differences appear in the other branches which are furnished, in animals, by the 

 superior maxillary nerve : in Man these branches leave Meckel's ganglion. The fila- 

 ments leaving this ganglion are : 1, The pharyngeal nerve of Bock which is distributed in 

 the upper portion of the mucous membrane of the pharynx, in that of the Eustachian 

 tube and the posterior orifice of the nasal cavities ; 2, The palatine nerves great or 

 anterior sent to the mucous membrane of the anterior portion of the palate; middle 

 palatine, distributed to that of the soft palate, and posterior palatine, that goes to the two 

 faces of the soft palate and its muscles ; 3, The nasal or spheno-palatine nerve. 



The inferior maxillary nerve closely resembles that of animals, the only differences 

 consisting in: 1. The deep middle temporal nerve rising direct from the maxillary; 

 2, The Ijngual nerve is detached near the base of the cranium ; 3, The superficial 

 temporal nerve furnishes, independently of the filaments uniting it to the facial, an 



