SPINAL AND SYMPATHETIC NERVES. 371 



that it takes in the formation of the crural sheath, have been before 

 explained (p. 293). 



Dissection. The student is now to remove the right kidney and Trace the 

 to clean the lymphatic glands lying along the vertebrae, and to trace y 

 upwards some lymphatic vessels to the thoracic duct. 



To show the origin of the duct, the diaphragm is to be divided 

 over the aorta, and its pillars are to be thrown to the sides : a piece 

 may be cut out of the aorta opposite the first lumbar vertebra. The 



beginning of the duct (receptaculum chyli), and the lower end of and the 

 r , , ,, , recepta- 



the large azygos vein may be well seen : and the two are to be cuium, and 

 followed upwards into the thorax. 



On the left side the student may trace the splanchnic nerves and splanchnic 

 the small azygos vein through the pillar of the diaphragm, and 

 may show the knotted cord of the sympathetic nerve entering the 

 abdomen beneath the arch over the psoas muscle. 



LYMPHATIC GLANDS. A chain of glands is placed along the side Lumbar 

 of the external iliac artery, and along the front and sides of the gUmds* 1C 

 lumbar vertebras ; they are connected by short tubes, which increase 

 in size and diminish in number, and opposite the first lumbar ducts end in 

 vertebra form one principal trunk which enters the thoracic duct. 

 Into the glands the lymphatics of the lower limbs, and those of 

 some of the viscera and of the wall of the abdomen are received. 



Another cluster of large glands surrounds the coeliac axis, and Coeliac 

 covers the upper end of the abdominal aorta. They are distinguished g 

 as the cceliac glands, and receive the lymphatics of the stomach, 

 spleen, pancreas, and great part of the liver. Their ducts unite ducts join 

 with those of the mesenteric glands, and give rise to one or more inte^ine 

 large trunks, which pass to the common thoracic duct. 



RECEPTACULUM CHYLI. The thoracic duct begins in the abdomen Beginningpf 

 by the union of three or four large lymphatic trunks. Its commence- duct, 

 ment is marked by a dilatation, which is placed on the right side of 

 the aorta, opposite the first or second lumbar vertebra. The duct 

 enters the thorax by passing through the diaphragm with the aorta. 



THE SPINAL AND SYMPATHETIC NERVES. 



The spinal nerves of the loins enter into a plexus, and supply the 

 limb and the contiguous portions of the trunk. 



Dissection (fig. 140, p. 373). The lumbar nerves and their plexus Dissection 

 are to be learnt on the left side, although the woodcut shows them ba r p ^ e xu^ 

 on the right side ; and to bring them into view, the dissector should on leffc side > 

 cut through the external iliac vessel, and afterwards scrape away 

 the psoas. For the most part the fleshy fibres may be removed 

 freely ; but a small branch (accessory of the obturator) should be 

 first looked for at the inner border of the muscle. On, or in the 

 substance of, the quadratus lumborum a communication' may be 

 sometimes found between the last dorsal and the first lumbar nerve. 



The cord of the sympathetic nerve lies along the edge of the wit j| s )" m - 

 psoas, and offsets of it join the spinal nerves ; these are to be followed FS 

 back along the lumbar arteries. 



B B 2 



