SYMPATHETIC NERVE. 



425 



wards of the sympathetic cord. According 

 to Bourgery*, the common sympathetic trunk 

 may be regarded as dividing at the inferior 

 cervical ganglion into an anterior and a pos- 

 terior portion; the former, corresponding to 

 the continuation of the cord in the neck, he 

 terms the carotid track, the latter, correspond- 

 ing to the vertebral branch, he terms the pos- 

 terior or vertebral track. He describes it 

 as arising from the plexus formed around the 

 subclavian artery : it is quite visible to the 

 naked eye at its origin, but higher up its 

 filaments become microscopic in point of 

 size: the vertebral branches, or tracks of 

 opposite sides, unite together in the groove 

 lodging the basilar artery, and communica- 

 tions are also formed between them and the 

 anterior, or carotid track, by means of fila- 

 ments which pass backwards with the pos- 

 terior communicating arteries. The vertebro- 

 basilar nervous apparatus, as it is termed by 

 him, supplies nerves to the vessels, which 

 ramify on the cerebellum and posterior lobe 

 of the cerebrum. 



(c) Inferior or small Cardiac Nerve. The 

 inferior cardiac arises by one or two roots, 

 passes inwards behind the subclavian artery, 

 and terminates in the deep cardiac plexus. It 

 forms communications with the middle car- 

 diac nerve, as also with the cardiac branch of 

 the recurrent laryngeal. Frequently, espe- 

 cially on the left side, the lower cardiac 

 branch becomes united with the middle car- 

 diac, giving rise to what has been termed the 

 Nervus cardiacus crassus. The communi- 

 cating branch between the lower cervical and 

 first thoracic ganglion is very short, some- 

 times wanting, the two ganglia running into 

 one another. 



II. Thoracic portion of the Gangliated Cord. 

 The thoracic portion of the gangliated cord 

 of the sympathetic lies on each side of the 

 spinal column, in front of the transverse pro- 

 cesses of the vertebrae and heads of the ribs, 

 and beneath the pleura. It is continuous 

 above with the cervical portion, and below 

 it passes into the abdomen, between the pil- 

 lars of the diaphragm and superior extremity 

 of the psoas muscle, outside the splanchnic 

 nerves, becoming continuous with the lumbar 

 portion of the sympathetic cord. The num- 

 ber of the ganglia varies : they are commonly 

 eleven, rarely twelve, on each side. They 

 are, in general, situated between the heads of 

 the ribs in front of the transverse processes 

 of the vertebrae, and present commonly a 

 more or less triangular form. The cord 

 connecting the ganglia of either side runs in 

 front of the heads of the ribs, and is ge- 

 nerally single, though sometimes it is double. 

 The branches connected with the thoracic 

 ganglia are the following : 



() Communicating branches pass between 

 each of the ganglia and the corresponding 



* Memoire snr 1'extremite c^phalique du grand 

 sympathetique dans 1'bomme et les animaux mam- 

 miferes. par M. I. M. Bourgery. Comptes Rendus, 

 vol. xx. 



intercostal nerve : these are commonly double, 

 sometimes three, short, and pretty strong. 



(b) Branches of small size pass from the 

 ganglia to the descending aorta, forming a 

 plexus around it; others pass to the pul- 

 monary and cesophageal plexuses ; branches 

 are also described by Krause as passing be- 

 tween the ganglia of opposite sides in front 

 of the bodies of the vertebrae. 



(c) The chief branches leaving the thoracic 

 ganglia are the greater and smaller splanchnic 

 nerves. These are situated to the inner side 

 of the main cord of the sympathetic, and also 

 more anteriorly, upon the lateral and anterior 

 surface of the bodies of the vertebrae. They 

 are formed of branches derived from the six 

 lower thoracic ganglia, and pass through the 

 diaphragm into the abdomen. The greater 

 splanchnic nerve derives its roots commonly 

 from the inner part of the sixth, seventh, 

 eighth, and ninth, thoracic ganglia ; it often 

 also receives a branch from the fifth, and, 

 according to Dr. Beck, from the different 

 ganglia as high up as the first. It passes 

 obliquely downwards and slightly inwards 

 upon the sides of the vertebral column, in 

 front of the intercostal vessels, and covered 

 by the pleura. It enters the cavity of 

 the abdomen by perforating the pillars be- 

 tween the middle and internal crura of dia- 

 phragm, rarely through the aortic opening, 

 and terminates in the semilunar ganglion of 

 the cceliac plexus. The smaller splanchnic 

 nerve, which is sometimes double, springs 

 from the tenth and eleventh thoracic ganglia : 

 following the same course as the greater 

 splanchnic nerve, it is directed obliquely 

 downwards and inwards upon the body of 

 the twelfth dorsal vertebra, passes through 

 the diaphragm between the greater splanchnic 

 nerve and the communicating cord, which 

 unites the last thoracic to the first lumbar 

 ganglion, or pierces the middle cms of the 

 diaphragm. It terminates in the cceliac and 

 renal plexuses ; the branch to the latter being 

 generally stronger than that to the former. 



(d) The communicating cord between 

 the last thoracic ganglion and first lumbar 

 enters the cavity of the abdomen between 

 the middle and external crura of the dia- 

 phragm, or penetrates the latter. 



III. Lumbar portion of the Gangliated Cord. 

 The lumbar portion of the sympathetic 

 cord generally contains five ganglia, some- 

 times only three or four, and is situated 

 upon the lateral and anterior aspect of the 

 bodies of the lumbar vertebrae, in front of the 

 psoas muscle, behind and to the left of the 

 aorta on the left side, and behind and to the 

 right of the vena cava on the right. The 

 branches connected with the lumbar ganglia 

 are : (a) Branches of communication with 

 the lumbar nerves: these are commonly two in 

 number for each ; they are longer than those 

 in the thoracic region, and pass between the 

 heads of the psoas muscle. (6) Branches also 

 pass off from the ganglia to the aortic, spermatic, 

 renal and superior hypogastric plexuses. (V) 



