T8S 



y;//: .v /:/, i -/-x 



o\\c - its chain-like aspect ; tlicy are usually elliptical in shape, though th< y 

 may also IK- round or seniilunar ; in all cases they arc studded with prolonga- 

 tions nt their borders. Beneath each of the regions of the spine tin y an- equal 

 in number to the vertebra}, with tho exception of tho cervical region, in 

 which are only two ono nt the top, the other at tho bottom, of tho neck. 



To this chain arrive offi-mit branches, by the union of which it is con- 

 stituted ; these branches are furnished by the nerves of the medulla oblonirala 

 and the inferior spinal brandies, except those of the coccygeal region. The 

 afferent branches join the sympathetic nt each ganglion ; but as there are 

 only two ganglia in the region of the neck, the afferent filaments of the 

 cervical nerves are grouped in such a manner as to reach the superior and 

 inferior ganglion. 



Those nerves which are given off from the ganglia to be distributed to 

 the viscera, are named the efferent or emergent branches. They are interlaced 

 around the arteries to reach their destination, forming plexuses on the surface 

 of these vessels. 



This general idea of the disposition of the great sympathetic is sufficient 

 to show that its double ganglionic chain does not represent two particular 

 nerves arising at one determinate point, and ending at 

 another. Properly speaking, they have neither origin 

 nor termination ; they are always giving off branches 

 which are as frequently replaced by others : in this way 

 they might be compared, in this respect, to the median 

 spinal artery, which offers somewhat the same mode of 

 constitution with its affercnts supplied by the spinal 

 branches from the intervcrtebral foramina, and its efferents 

 destined to the substance of the spinal medulla. 



STRUOTUKK. The ganglia of the great sympathetic 

 differ but little in their structure from the spinal ganglia, 

 whose constitution has been already made known. They 

 have an envelope of connective tissue, which sends very 

 fine septa into their interior. In tho spaces are cells 

 a little smaller and paler than those of the spinal gan- 

 glia ; they are round, or furnished with poles that bring 

 them into communication with tho afferent and efferent 

 <;A\- nerve-tubes; there are also, in the ganglia, tubes which 

 A only pass through it, and merely lie beside the cells. 



The afferent branches of the ganglia have the white tint 

 the of the ccrebro- spinal nerves, and are named the ijn ij 

 nerves. They owe their colour to the fibres of Itenml.-, 

 which they contain in large quantity. Witli these 

 nucleated fibres are associated fine nerve-fibres, and 

 divide into two fas- double-contoured fibres which proceed from tho coin- 

 ciculi which pass mun f cating ran ,{ or aflVrcnt filaments supplied by the 

 upwards and down- . , J ', /.. i i- 



wards in the trunk ; spinal nerves ; these fibres oiten leave tho ganglia to 



c, c, The ganglion pass directly to organs. 



composed of gan- J n describing tho sympathetic chain, it is divided into 



glion cells ;d, Small fiye gect i ons . ft cephalic, cercical, dorsal, lumbar, and 

 branch, probably , 



YVPATUKT1C 



(1UOX FROM 

 PUPPY. 



a, a, Trunk of 

 sympathetic nerve; 

 '<, Communicating 

 brnm-hes from ti 

 spiunl nerve ; these 



destined to accom- 

 pany an artery ; c, 

 Visceral branch. 



saci'al. 



1. Cephalic Portion of the Sympathetic. 



This is composed of tho spheno-palatine, ophthalmic, 

 and otic ganglia, all of which communicate with the superior cervical 



