720 DIVISIONS OF THE SYMPATHETIC. 



intercalated in each fiber. The sympathetic fibers have the same peripheral 

 area of distribution as do the sensory fibers of the roots of the same spinal 

 nerve. 



4. The cervical sympathetic cord and the splanchnic nerves are believed to 

 contain fibers irritation of which excites in a centripetal direction the cardiac in- 

 hibitory system in the medulla oblongata. 



767, 



vical to 



from the solar ganglion. 



6. The significance of the celiac and mesenteric plexuses is discussed on pp. 328 

 and 359. After extirpation of the celiac ganglion Lamansky observed transitory 

 derangement of digestion, in consequence of which undigested food was discharged 

 from the anus. 



7. Sweat-fibers are discussed on p. 536. 



8. Finally, the abdominal division of the sympathetic contains motor and 

 vasomotor fibers for the spleen, the large intestine (to which they pass with the 

 arterial trunks), the bladder, the ureters (to which they pass in the hypogastric 

 plexus), the vasa deferentia and the seminal vesicles. Irritation of any of these 

 nerve-tracts causes increased movement of the organs in question, the diminished 

 supply of blood also acting as an exciting factor. Section causes vascular dilata- 

 tion, with secondary derangement of the circulation, and finally of the nutrition. 

 The relations of the adrenal bodies to the sympathetic have been discussed on 

 p. 107. The renal plexus is described on p. 515, and the cavernous plexus in con- 

 nection with erection on p. 955. 



From the lumbosacral portion of the spinal cord there issue as sympathetic 

 filaments almost exclusively medullated fibers that pass in the sympathetic cord 

 and thence partly to the inferior mesenteric ganglion and thence to the hypo- 

 gastric and inferior mesenteric nerves, and partly through the sacral sympathetic 

 ganglia to the sacral nerves to the skin. 



The lumbar branches contain inhibitory fibers for the musculature of the 

 descending colon and the rectum. Inhibitory and motor fibers pass to the internal 

 sphincter ani. Irritation of the branches causes also contraction of the unstriated 

 muscle-fibers of the skin surrounding the anus and 'pallor of the anal mucous 

 membrane. 



The sacral branches send motor fibers to the rectum and the colon, in addition 

 inhibitory fibers to the internal sphincter ani, the adjacent musculature of the skin 

 and vasodilators to the mucous membrane of the rectum and the external geni- 

 talia. The inferior mesenteric ganglion acting as a reflex center may transmit 

 motor impulses to the bladder in response to irritation of sensory nerves of this 

 viscus. 



Pathological. In accordance with the varied ramifications of the sympathetic 

 it offers a wide field for pathological disturbances. It should be stated that 

 affections of all of the fibers related to the vascular system are discussed elsewhere 

 (P- 77). 



The cervical sympathetic is most frequently paralyzed or irritated by direct 

 traumatic influences. Gunshot-wounds or punctured wounds, tumors, enlarged 

 lymphatic glands, aneurysms, inflammations of the apices of the lungs and the 

 adjacent pleura, exostoses of the vertebral column may exert in part an irritant, 

 in part a paralyzant effect. The resulting symptoms have been in part analyzed 

 in the discussion of the ciliary ganglion (p. 684). Irritation of the cervical sympa- 

 thetic causes in man dilatation of the pupil (spastic mydriasis) , together with pallor 

 of the face and occasionally hyperidrosis ; disorders in near vision, the pupil being 

 unable to contract, so that spherical aberration must have a disturbing effect; 

 protrusion of the eyeball, with widening of the palpebral fissure. Paralysis causes 

 an increased supply of blood to the affected side of the head, occasionally in 

 association with anidrosis. The reddening may increase to a pathological degree. 

 Later on, paralysis of the cervical sympathetic is attended with dilatation of the 

 pupil (paralytic myosis), which in the act of accommodation undergoes change 

 in diameter, but not on stimulation by light; it is slightly dilated by atropin. 

 At the same time the palpebral fissure is narrowed, the eyeball retracted, the 

 cornea somewhat flattened, and the tension of the eyeball diminished. Irrita- 

 tion of the sympathetic has been attended with increased secretion of saliva 

 Among the symptoms of irritation of the cervical sympathetic described, unil 



