' SYMI'ATIIHTK' 77.-r.YA>; 1003 



other nerves or with the organs with whcne innervation they are concerned. The 



connecting trunks and raini may lie divided into (<n tlic mini i-n/iuini/iin/iiti x. or 

 c/ntnil limnrliix, cunncct inic the sympathetic with the cerenro-spinal and central 

 systems; (b) OUodative tnutkt, best considered as those \\hich connect sympa- 

 thetic ganglia sit uateil on the MI me side of t he body ; (c) COmmittunil bnmdut, Ot 

 those which connect iranglia .situated on opposite sides of t he mid-line of the body, 

 such us the transverse connect in-; branches bet \vern the syniputliet ic trunk in the 

 himbo-sacral region (liir. "I'.M. or all the connecting trunks between the ganglia of 

 plexuses occupying the mid-region of the body; (<l) hrtninul or peripheral hrnni-lii-x, 

 or tlio.se which pass from the ganglia to their final distribution apparently uninter- 

 rupted by other ganglia. 



THE SYMPATHETIC TRUNKS 



The sympathetic trunks, or gangliated cords, of the sympathetic system are two 

 symmetrical trunks with ganglia interposed in them at intervals of varying regu- 

 larity, and extending vertically, one on each side of the ventral aspect of the verte- 

 bral column, from the second cervical vertebra to the first piece of the coccyx. 

 Upon the coccyx the two trunks unite and terminate in a single medial ganglion, the 

 ganglion coccygeum impar. The various ganglia are connected with the spinal 

 nerves by the raini communicantes. Morphologically, each trunk might be expected 

 to possess thirty-one ganglia, one for each spinal nerve, but, owing to the fusion of 

 adjacent ganglia in certain regions, especially the cervical, there are in the adult only 

 twenty-one or twenty-two ganglia in each trunk. These occur as three cervical 

 i/tniglia, ter\ or eleven thoracic ganglia, jour lutnbar and Jour sacral ganglia, and the 

 ganglion coccygeum impar, which is common to both trunks. 



In the cervical region the sympathetic trunks lie in front of the transverse proc- 

 esses of the vertebra?, from which they are separated by the longus capitis (rectus 

 capitis anticus major) and longus colli ; in the thoracic region they lie at the sides of the 

 bodies of the vertebrae and on the heads of the ribs ; in the lumbar region they are 

 placed more ventrally with reference te the spinal nerves and more in front of the 

 bodies of the vertebrae and along the ventral borders of the psoas muscles; in the 

 pelvis the ganglia lie between and ventral to the openings of the sacral foramina. 

 In the lower lumbar and sacral region one ganglion may send rami communicantes to 

 two spinal nerves and one spinal nerve may be connected with two ganglia. The 

 ganglia of the trunks throughout give off associative branches to the ganglia of the 

 pre vertebral plexuses and branches to the nearby viscera and blood-vessels. These 

 branches may appear either white or grey according to the predominance of medullated 

 or non-mtxlullated fibres in them. In the lumbo-sacral region commissunfl or trans- 

 verse connecting branches between the ganglia of the two trunks are especially abun- 

 dant . I n connecting trunks having a whiter appearance, the greater part of the med- 

 ullated fibres producing it are fibres from the spinal nerves which have passed through 

 the sympat hetic ganglia without termination and are passing on their way to termi- 

 nate about the cells of more distant ganglia situated either in the prevertebral plexuses 

 or in the ganglia of the terminal plexuses. The trunks connecting the ganglia of the 

 sympathetic trunks all contain three varieties of fibres : (1) Fibres which have entered 

 them in the white rami communicantes from the spinal nerves of higher or lower 

 levels, and which are coursing in them to terminate in other ganglia, either in the 

 trunks above or below or in ganglia not belonging to the trunks; (2) fibres arising in 

 sympathetic ganglia of a higher or lower level and passing upwards or downwards to 

 terminate in other ganglia of the trunk or to issue from the trunk and proceed to more 

 peripheral ganglia or to ganglia of the opposite trunk (both associative and com- 

 missural fibres); (3) splanchnic afferent fibres or sensory fibres arising either in the 

 spinal ganglia, or sensory sympathetic fibres arising in sympathetic ganglia and 

 coursing in the trunk to pass into spinal ganglia above or below by way of the grey 

 rami communicantes. - 



THE CEPHALIC AND CERVICAL PORTIONS OF THE SYMPATHETIC 



TRUNK 



The cephalic portion of the sympathetic system consists of small Lrandia and of 

 numerous plexuses connected with the internal carotid nerve, the ascending branch 



