NEUROLOGY. 141 
angular, the base towards the spine, the apex external, covered by the 
pleura and a thin fascia. All communicate by their external branches with 
the anterior or intercostal branches of the spinal nerves. From the base or 
anterior edge of each ganglion, arise the internal branches, the mediastinal, 
and the great and lesser splanchnic. 
The great splanchnic nerve arises by four or five distinct roots from the 
sixth, seventh, eighth, ninth, and tenth ganglions; they descend forwards 
and unite into a long, flat cord which enters the abdomen, where each 
nerve expands into the semilunar ganglion. The real origin of this nerve 
is from the cerebro-spinal system. 
The lesser splanchnic nerve arises by two roots from the tenth and 
eleventh ganglions, which unite on the side of the last dorsal vertebra. 
The small nerve thus constituted enters the abdomen through the crus of 
the diaphragm, and then ends in the renal plexus. 
The semilunar ganglion of each side is situated on the diaphragm, and 
partly on the aorta, on either side of the coeliac axis, and above and behind 
the supra-renal capsule. These are the largest ganglions on the sympa- 
thetic; though called semi-lunar, their form 1s very variable and irregular, 
and frequently instead of a single mass they consist of a congeries of knot- 
ted ganglions on the nervous cord; the right and left communicate with 
each other by several filaments, on which again small ganglions are placed. 
This communication surrounds the cceliac axis, and, as branches radiate 
from it in all directions, it is termed the solar plexus. This plexus is 
situated in the epigastrium, behind the stomach, in front of the aorta, and 
above the pancreas. In this plexus there are also some filaments from the 
lesser splanchnic and phrenic nerves, and the right vagus terminates in it ; 
it is the most highly developed portion of the sympathetics, and has been 
regarded as the head or centre of the great organic nervous system by 
some, who maintain the independence of the ganglionic system and its dis- 
‘tinctness from the cerebro-spinal nerves. From it numerous nerves pass 
off in various directions; these nerves accompany the blood-vessels, and 
form plexuses around each, which are named, according to their destination, 
hepatic, splanchie, gastric, &c. 
1. The phrenic plexuses consist of branches arising on each side from 
the upper part of the solar plexus, accompany the phrenic arteries, and 
enter the diaphragm beneath the peritoneum; some branches follow the 
phrenic vessels, others pass in different directions, and join some minute 
filaments from the phrenic nerves of the cervical plexus. 
2. The supra-renal plexuses arise partly from the last, and, by some deli- 
cate filaments from the semilunar ganglion of each side, they twine around 
the arteries which conduct them into the supra-renal bodies. 
3. The coronary or gastric plexus. This fasciculus arises from the upper 
and anterior part of the solar and from the right vagus, and accompanies 
the arteria coronaria ventriculi, along the lesser curvature of the stomach, 
to the lesser omentum ; its filaments are lost in the submucous tissue, and 
‘communicate with those of the right and left vagi. 
sir 4: The hepatic plexus is a very large fasciculus, arising partly from the 
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