SYMPATHETIC NERVE. 



487 



Each ganglion furnishes external branches to communicate with 

 the spinal nerves, and internal for the supply of the viscera. 



nal or connecting branches (fig. 176). Two offsets pass out- 

 wards from each ganglion to join a spinal nerve (intercostal). In the 

 branches of communica- 

 tion both spinal and sym- 

 pathetic nerve-fibres are 

 combined ; but one {white 

 minus communicans) (h) 

 consists almost entirely of 

 spinal, and the other (grey 

 ra in us comm u means) (i) 

 mainly of sympathetic 

 fibres. 



The internal or visceral 

 Irnnches differ in size and 

 distribution, according as 

 they are derived from the 

 upper or lower ganglia. 



The offsets of the upper 

 Jive ganglia are very small, 

 and are distributed to the 

 aorta, and to the vertebrae 

 with the ligaments. From 

 the third and fourth 

 ganglia also, offsets are 

 sent to the posterior 

 pulmonary plexus. 



The branches of the lower 

 seven ganglia are largerand 

 much whiter than the 

 others, and are united to 

 form visceral or splanchnic 

 nerves of the abdomen : 

 these are three in number 

 (large, small, and smallest) 

 and pierce the diaphragm 

 to end in the solar and 

 renal plexuses. 



The great splanchnic 

 nerve is a lar^e white 



Branches : 



to join 

 spinal 



nerves ; 



to supply 

 viscera. 



Offsets of 

 upper five 

 ganglia are 

 small ; 



FIG. 176. SCHEME TO ILLUSTRATE THE CON- 

 NECTION BETWEEN THE SPINAL AND SYM- 

 PATHETIC NERVES (ToDD AND BOWMAK). 



a. Posterior root of a spinal nerve, with a 

 ganglion, c. 



b. Anterior root. 



d. Posterior primary branch. 



e. Anterior primary bianch of the spinal 

 nerve. 



/. Knotted cord of the sympathetic. 



g. Ganglia on the cord. 



h. ^Yhite offset from the spinal to the 

 sympathetic rerve. 



i. Grrey offset from the sympathetic to the 

 spinal nerve. 



of lower 

 seven, large, 

 and form 



cord, which receives roots 



apparently from only four or five ganglia (sixth to the tenth), but 

 its fibres may le traced upwards on the knotted cord as high as 

 the third ganglion. Descending on the bodies of the vertebrae, it 

 pierces the fibres of the crus of the diaphragm, and ends in the 

 seniilunar ganglion of the abdomen. At the lower part of the 

 thorax the nerve may present a ganglion. 



The small splanchnic nerve begins in the tenth and eleventh 

 ganglia, or in the intervening cord. It is transmitted interiorly 



great 

 splanchnic 



to semilunar 

 ganglion ; 



small 

 splanchnic 

 to cceliac 

 plexus ; 



