NERVOUS SYSTEIVl. 357 



like course upon the outer side. Their subsequent course and 

 ultimate distribution are the same as those of the plantar nerves 

 of the fore extremity. Its branches are — 1. A long branch 

 which at first accompanies the popliteal trunks, then passes be- 

 tween the gastrocnemius externus and lower end of the semi- 

 membranosus, and makes its appearance upon the faschia cover- 

 ing the outer side of the thigh, where it sends off many cutaneous 

 filaments, and ramifies over the outer part of the hock. 2. A 

 long slender branch to the gastrocnemius internus. 3. Several 

 filaments to the skin and faschia, above and about the hock. 



The second popliteal nerve passes also between the bellies of 

 the gastrocnemii, above the first, detaching twigs to them in its 

 passage, and then expands into many branches which penetrate 

 the heads of the flexor muscles of the foot, and send filaments 

 into the stifle-joint. 



The third popliteal nerve, leaving the others, winds rounds to 

 the outer part of the thigh, between the gastrocnemius externus 

 and the semimembranosus ; there it crosses the head of the pe- 

 roneus, and then suddenly turns down, running between that 

 muscle and the extensor pedis, along with the anterior tibial 

 artery, and takes its course with it to the middle of the cannon, 

 whence (instead of accompanying that vessel between the meta- 

 tarsal bones) it pursues its way along the side of the large me- 

 tatarsal bone, over the fetlock -joint, and terminates subcuta- 

 neously upon the side of the pastern. Its branches are — 1. A 

 small one to the semimembranosus. 2. A filament, or two, to 

 the gastrocnemius externus. 3. A large branch that runs along 

 the peroncus, under the faschia, and ends superficially in front 

 of the hock. 4. Branches to the flexor metatirsi and extensor 

 pedis. 5. Various small subcutaneous filaments during the 

 remainder of its course. 



Sympathetic Nerve. 



This nerve (designated sympathetic, from the universal influ- 

 ence which it possesses in the nervous system) is one no less 

 remarkable for its vast and vital importance in the animal 

 economy than for its extensive distribution all over the body, 

 from the head to the tail ; for its ganglia ; its plexuses ; the 

 number and complication of its branches ; and its frequent inter- 

 course and connexion with other nerves belonging to the head, 

 neck, chest, abdomen, and pelvis. Indeed, late experimental 

 researches lead us to consider it as a nervous system of itself, 

 or at least one that renders the parts to which it furnishes nerves, 

 constitutional orLians less under the influence of the scnsoriuni. 



