THE GREAT SYMPATHETIC NERVOUS SYSTEM. 885 



tuberosity it divides into two branches — an inferior or perineal, and a superior or dorsalis penis 

 nerve. The latter is placed on the dorsum of the penis, and reaches tlie mucous membrane of 

 the glans and prepuce; the former does not go beyond the muscles and integuments of the 

 perineum. 6. The superior gluteal nerve. 7. Nerve of the pyramidalis. 8. Nerve of the 

 superior gemellus. 9. Nerve of the inferior gemellus and quadratus cruralis. 10. The small 

 sciatic, or inferior gluteal nerve, the inferior or femoral branch of whicii is very long, descend- 

 ing, as it does, to the middle of the posterior face of tlie thigh, beneath the crural aponeurosis, 

 to the popliteal space, where it becomes superficial, and terminates in the skin of the upper 

 portion of the leg. 



The terminal branch of the sacral plexus forms the great sciatic nerve, the distribution of 

 which is the same as that of Carnivora. The collateral ramuscules of the great sciatif are the 

 branch of the long portion of the biceps ; the semitendinosus and semimeiubranosus branch ; the 

 branch to the great adductor; and, lastly, tliat to the short portion of the biceps. It terminates 

 by the external and internal popliteal. 



Tiie musculo-cutaneous and anterior tibial, continuations of the external popliteus, comport 

 themselves almost the same as in the Dog. They form dorsal collaterals to the third, fourth, 

 and fifth toes, as well as to tlie second. 



The internal popliteal presents an external saphenous nerve that passes along the external 

 border of the foot, and has, in addition, a branch that ascends on the dorsum of that organ. 

 The external saphenous furnishes the dorsal collaterals to the first toe, and the external 

 collateral to the second. Tlie posterior tibial nerve continues the internal sciatic in the leg; it 

 terminates in the plantar nerves. The internal plantar furnishes the collateral nerves to the 

 fifth, fourth, and third toes, and the internal collateral of the second toe. The external 

 divides into three branches : the two superficial branches form the collaterals of the first toe, 

 and the external collateral of the second ; the deep branch passes inwards, behind the inter- 

 osseous muscles, and is expended in those of the fourtii space, after giving filaments to the 

 oblique abductor of the large toe, transverse abductor, last two lumbricales, to the interosseous, 

 and very fine filaments to the articulations of the tarsus with tlie metatarsus. 



It will therefore be seen, that, in Man, the brandies of the deep trunk of the external 

 plantar join those of the internal plantar, to form the collateral nerves. 



CHAPTER III. 



THE GREAT SYMPATHETIC NERVOUS SYSTEM. 



Preparation of the Great Sympathetic— 7%e same subject ought to suffice for the prepara- 

 tion of this as well as for the pneumogastric and spinal nerves. After placng the animal in 

 the first position, the intestines are remuved, one of the posterior limbs cut off, and the greater 

 portion of the os innominatum cleared away by sawing through the symphysis pubis and the 

 neck of the ilium ; the dissection of all the abdomino-pelvic portion of the system, and that of 

 the terminal branches of the pneumogastric nerve, is then proceeded with. The anterior limb 

 of the same side should be afterwards detached, the scapula having been previously sawn 

 across its middle part, and tlie thorax thrown open by the ablation of the entire costal wall, in 

 sawing throu^di the sternal cartilages below, and the ribs above, at their superior extremity. 

 All the thoracic portion of the ganglionic nervous apparatus, and the pneumogastric nerves, 

 may then be prepared, Notliing more remains to be accomplished except the dissection of 

 tlie sympathetic and the vagus nerve in the cervico-cephalic region, with that of the spinal 

 nerve ; this operation is not attended with any difficulty, and should be preceded by the extir- 

 pation of a branch of the inferior maxilla. It is useful to inject the arteries previously ; as 

 then the filaments of the sympathetic that lie alongside the vessels of the different organs in 

 the abdominal cavity can be more easily followed. 



The great sympathetic, also named the trisplanchnir system ((nrXavxvov, an 

 intestine or viscus), because of its position and destination, is the nervous appa- 

 ratus of the organs of vegetative life. 



