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FUNCTIONS OF THE CERVICAL SYMPATHETIC. 



I. Independent Functions of the sympathetic are those of certain nerve plexuses 

 which remain after all the nervous connections with the cerebrospinal branches 



have been divided. 



The activities of these plexuses may be influenced either in 

 the direction of inhibition or stimula- 

 tion through fibres reaching them 

 from the cerebro-spinal nerves. 

 To these belong : 



1. The automatic ganglia of the 

 heart ( 58). 



2. The mesenteric plexus of the in- 

 testine (161). 



3. The plexuses of the uterus, Fal- 

 lopian tubes, ureters (also of the blood- 

 and lymph-vessels). 



II. Dependent Functions. Fibres 

 run in the sympathetic, which (like 

 the peripheral nerves) are active only 

 when their connection with the central 

 nervous system is maintained, e.g., the 

 sensory fibres of the splanchnic. Others 

 again convey impulses from the central 

 nervous system to the ganglia, while 

 the ganglia in turn modify the impulses 

 which inhibit or excite the movements 

 of the corresponding organs. 



The following statement is a resume of the 

 functions of the sympathetic, according to 

 the anatomical arrangement : 



A. Cervical Part of the Sympa- 

 thetic. 1. Pupil-dilating fibres (com- 

 pare Ciliary ganglion, 347, I., and 

 Iris, 392). According to Budge, 

 these fibres arise from the spinal cord, 

 and run through the upper two dorsal 

 and lowest two cervical nerves into the 

 cervical sympathetic, which conveys 

 them to the head. Section of the cer- 

 vical sympathetic or its rami communi- 

 cantes causes contraction of the pupil. 

 (The central origin of these fibres is 

 referred to in 362, 1, and 367, 8.) 



2. Motor fibres for Muller's smooth 

 muscle of the orbit, and partly for the 

 external rectus muscle ( 348). 



3. Vaso-motor branches for the 

 outer ear and the side of the face (CI. 

 Bernard), tympanum (Prussak), con- 

 junctiva, iris, choroid, retina (only in 

 part see Ciliary ganglion, 347, I.), 



for the vessels of the oesophagus, larynx, thyroid gland fibres for the vessels of the 

 brain and its membranes (Bonders and Callenfels). 



4. In the cervical portion are afferent fibres which excite the vaso-motor centre 

 in the medulla (Avbert). 



5. Secretory (trophic) and vaso-motor fibres for the salivary glands ( 145). 



3 S-o 



