THE SYMPATHETIC NERVE. 481 



under various circumstances of size and form. It is more flat- 

 tened than the preceding, and never so long. Sometimes it is 

 double. Like the preceding, it has a great many filaments at- 

 tached to, or emanating from it. 



The external filaments, amounting to about three in nunrber, 

 pass from it to the anterior fasciculi of the fourth, fifth and sixth 

 cervical nerves, between the origins of the scaleni muscles. 

 Some of its filaments accompany the inferior thyroid artery, 

 and, along with the superficial cardiac, form a plexus around 

 it, which reaches to the thyroid gland. 



The Middle Cardiac Nerve is formed by several of the ante- 

 rior branches, collecting into a single chord. The latter de- 

 scends along the external side of the primitive carotid, crosses, 

 on the right side of the body, the root of the subclavian artery, 

 and then going along the posterior face of the arteria innomina- 

 ta, it gets between the aorta and the bifurcation of the trachea, 

 where it is merged in the commencement of the cardiac plexus 

 of nerves. On the left side, the middle cardiac nerve is formed 

 by an assemblage of filaments from the middle and inferior cer- 

 vical ganglions, which descend along the left subclavian artery 

 to the aorta, and are joined, on the front of the latter, by the su- 

 perficial cardiac nerve. On both side, these cardiac nerves 

 form intricate anastomoses with the pneumogastric nerve and 

 its recurrent branch. 



3. The Inferior Cervical Ganglion, situated as mentioned, 

 near the head of the first rib, like the others, is subject to vari- 

 ations in its form and size. Several filaments may be traced 

 between it and the middle cervical ganglion. One penetrates 

 into the canal of the transverse processes along with the verte- 

 bral artery, and, forming a plexus around it, may be traced dis- 

 tributing branches to the heads of the contiguous muscles, as 

 high up as the second cervical vertebra. 



The external branches of the inferior cervical ganglion are 

 numerous and small. Some of them anastomose with the an- 

 terior fasciculi of the two or three inferior cervical and the first 

 dorsal nerve. Others form a plexus around the subclavian ar- 

 tery, and follow the latter, in its distribution, to the upper ex- 

 tremity and to the shoulder. 



The anterior branches of this ganglion concur, after some 

 VOL. II. 42 



