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Show 2W unamv-vm - 'u'mvmm 172 in 1/96 difiercnt Paris (ff/M Bna'y. Oftbt particular Distribution (y‘I/fic AI (If/16111 Vutsclt they do not enter its substance. From his amazing accuracy it is impos- sible to doubt the author ; but as the ner\ es are very frequently forming 172 the back, the thoracic duct splits into two, and then unites again; this is what Haller calls insulamfacieur; sometimes it splits into several branches which again unite, as in the former example; sometimes it forms a numbei rings and net-work round the trunks of arteries, without appearing to be inserted into them, while at the same time we have the strongest proofs of of these islands, and sometimes it forms none. these arteries being influenced by the mind, as in blushing, anger, the the aorta, the thoracic duct crosses, as I have said, from the right side of the spine to the left, and when full, or injected with a coloured fluid, mav erection of the penis, Clytoris, and nipples. As we find the only power the mind has over muscles, is by means of the nerves, so we conclude that If when arteries are thus affected, it must be through the same medium. arteries are all‘ected by the mere contact of their own nerves, which may be the case for any thing we know, though muscles are not, so may the thoracie duct.-As nerves, however, in order to inlluence muscles, must be inserted into them, so we should naturally presume, that in order to in- fluence artt‘ries they should also be inserted into them. Professor "'alter says, they actually are inserted into the muscular coats of artertc ,his terms are, " Surculi qui in tunica musculari aortze implantantttr-Sut'culus qui in tunica musculat‘i aorta: consumitur--Nervus qui arteria: implantatur;"-- but as he denies such terminations in the thoracic duct, and as I have never seen any such, so I have no doubt of the absorbent system being less de- pendant on the nerves, than the muscles or arteries; yet, as the mode and extent of nervous influence is not known, so I contend that the nonvinsertion ofthe nerves into the thoracic duct, is no proof that they have no influence over it ; besides, the. nerves entering the coats ofthe thoracic duct, may be too small to be capable ofbeing shewn by dissecrion. The nerves going to the Having passed the arch of be seen on the left of the (esophagus distinctly through the pleura, withotit any other dis ection than that of opening the chest, and turning forward the lungs. After this, the thoracic duct, emerging from the cavity of the chest, gets above the pleura, and lies upon the muscle longus colli, and behind the arteria thyroidea inferior; at this place it enlarges considerably, and though its destination is the angle of the subclavian and jugular veins, it passes by that angle, forms a considerable curve, and descends to its termination, I formerly supposed, with a view to give its lluids the advantage of their own gravity in overcoming the resistance made to their entering the veins; but it is much more probable that this curve is formed to give room for the insertion ofa ntttnber of large trunks, which join it just before its entrance into the veins. It sometimes, though rarely, happens, that the thoracic duct does not pass by the angle of the jugular and subclavian, but ascends to its termination. Haller says, " In venarn suam aseenderit neqne surgerit, supra subclavios truncos-id semel puto in honiine vidi ant his, vidit ctiant accuratissitnus Cassebohmius." Before its insertion, and whilst it is behind the jugular vein, it commonly splits into two, three, or more teeth in the adttlthuman body,have neverth been shewnby dissection; indeed, branches; these, for the most part, unite again, and the duct terminates in the hole through which the arteries enter, the veins and lymphatics return, the veins as a single trunk : sometimes they form two or three separate ter- and which is lined also by the internal periosteum, which besides must trans- minations; these terminations are sometimes in the jugular vein above the angle, more commonly in the subclavian vein, on the left side of the angle. mit these nerves, is little more than visible to the naked eye; how is it pos- sible then, that the nerves should be singled out, by dissection, from these accompanying vessels and periosteum:3 yet the great sensibility of the teeth Haller says, " Rarum enim, si ductus thoracicus in sinistram subclaviam, quidem sed multifidus et plusquam duobis ramis, tribusve, et pluribus, sui to heat, cold, and contact ofhard and soft bodies in health, as well as their tinem fecit, vidi tamen et in homine." intense feeling of pain in the tooth-ach, the dividing and burning the packet constantly a pair of valves at the entrance of the thoracic duct into the subclavian vein; these, on certain occasions, shut up the duct, and prevent the of vessels entering the teeth destroying this tooth-aeh, demonstrate sulh'» ciently their existence, in spite of anatomical dissection. About the sixth or seventh, or more frequently the eighth, vertebra 0f the In the human subject there are venous blood from flowing into it. lIaller, speaking of this valve, says, " Oilicium valvulae habere elarissimi viri censent, nt chylum in venam ad- mittat |