138 ANTHROPOLOGY. 



terior tilnal, or interosseal nerve, supplies muscles of the leg, and on the tarsus 

 divides into an external and internal branch, the latter of which, the con- 

 tinued trunk, passes to the first and second toes. 



The internal popUtaial ov posterior tibial nerve, is much larger than the pre- 

 ceding, being destined to supply the large muscles on the back of the leg, 

 and the muscles and integuments of the sole of the foot. In the ham it gives 

 off various articular branches, and one principal cutaneous branch, the 

 external saphenous. Continued down the leg, the posterior tibial nerve, at 

 the tendo Achillis, gives off several large branches, as the external and inter- 

 nal plantar to the lower surface of the foot. 



PI. 138, ßg. 2, crural nerve, and its distribution : ', crural vein ; ^, crural 

 artery ; % crural nerve ; % external cutaneous nerve ; *, branches embracing 

 the vessels ; ', saphena ; '• ', saphenous nerve ; ", cutaneous branch from the 

 peroneal nerve to the foot. Fig. 3, nerves of the sole of the foot : ', division 

 of the posterior tibial nerve into", the inner, and ', the outer plantar nerve; 

 *, division of the inner plantar nerve into four digital nerves ; ', division of 

 the outer into a superficial and a deep branch. 



C. Sympathetic System. 



In addition to the five small ganglions on each side, already noticed in 

 the description of the cerebral nerves, viz. the Casserian, the lenticular or 

 ophthalmic, the spheno-palatine or Meckel's, the sub-maxillary, the otic or 

 the ganglion of Arnold : also, the several ganglions on the posterior roots 

 of the spinal nerves : we find one continued chain of these bodies placed 

 along the vertebral column, on either side of the median line, and at regular 

 intervals. These ganglions, on each side, are all connected to each other, 

 and resemble a knotted cord ; these cords receive the name of the sympa- 

 thetic nerves. 



The sympathetic nerves, therefore, are two in number : they descend from 

 the base of the cranium perpendicularly along the neck, and are placed 

 anterior to the vertebrae, on the rectus capitis and longus colli muscles, and 

 behind the great vessels and nerves. At the upper end of the chest, each 

 of these nerves is divided by the subclavian artery into several branches, 

 which encircle that vessel, and unite below it in the thorax. Through this 

 cavity they descend, at first obliquely, backwards, and outwards, along the 

 side of the spine, over the heads of the ribs and their stellate ligaments, and 

 are covered by the pleura ; they then incline a little forwards, and pass 

 behind the true ligamentum arcuatom into the abdomen ; through this region 

 they descend obliquely outwards on the fore part of the lumbar vertebrae, 

 between the psoas muscles and the crura of the diaphragm ; they then sink 

 into the pelvis, keeping close to the sacrum, and descend along the anterior 

 surface of this bone obliquely inwards ; near its inferior extremity, or on 

 the first part of the coccyx, they unite and terminate in a small ganglion, 

 named coccygeal, or impar. The superior extremity of each sympathetic 

 nerve is connected by several filaments with several of the cerebral nerves. 

 Some of these connexions, particularly that with the sixth, have been impro- 

 perly termed the origin of the sympathetic; at the base of the cranium it 

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