GAXGLIATED SYMPATHETIC COEDS. 



687 



front of the vertebral column, and extend 

 from the base of the skull to the coccyx. 

 Superiorly they are connected with plex- 

 uses which enter the cranial cavity, while 

 iuferiorly they converge on the sacrum, 

 and terminate in a single ganglion on the 

 coccyx. The several portions of the cords 

 are distinguished as cervical, dorsal, lum- 

 bar, and sacral, and iu each of these parts 

 the ganglia are equal in number, or nearly 

 so, to the vertebrae on which they lie, 

 except in the neck, where there are only 

 three. 



Fig. 451. DIAGRAMMATIC OUTLINE OF THE SYM- 

 PATHETIC CORD OF ONE SIDE IN CONNECTION 



WITH THE SPINAL NERVES. 



The full description of this figure will be found 

 at p. 629. 



On the right side the following letters in- 

 dicate parts of the sympathetic nerves ; viz. 

 a, the superior cervical ganglion, communi- 

 cating with the upper cervical spinal nerves 

 and continued below into the great sympathetic 

 cord ; 6, the middle cervical ganglion ; c, d, the 

 lower cervical ganglion united with the first 

 dorsal ; d', the eleventh dorsal ganglion ; from 

 the fifth to the ninth dorsal ganglia the origins 

 of the great splanchnic nerve are shown ; I, the 

 lowest dorsal or upper lumbar ganglion ; ss, the 

 upper sacral ganglion. In the whole extent of the 

 sympathetic cord, the twigs of union with the 

 spinal nerves are shown. 



Connection of the ganyliated cords with 

 the c&rebro-spinal system. The ganglia are 

 severally connected with the spinal nerves 

 in their neighbourhood by means of short 

 cords ; each connecting cord consisting of 

 a white and a grey portion, the former 

 of which may be considered as proceeding 

 from the spinal nerve to the ganglion, 

 the latter from the ganglion to the spinal 

 nerve. At its upper end the gangliated 

 cord communicates likewise with certain 

 cranial nerves. The main cords interven- 

 ing between the ganglia, like the smaller 

 ones connecting the ganglia with the spinal 

 nerves, are composed of a grey and a white 

 part, the white being continuous with the 

 fibres of the spinal nerves prolonged to the 

 ganglia. 



The great prevertebral plexuses comprise 

 three large aggregations of nerves, or 

 nerves and ganglia situated in front of 

 the spine, and occupying respectively the 

 thorax, the abdomen, and the pelvis, 

 They are single and median, and are 



Fig. 451. 



Br 



