NEUROLOGY 



glionic sympathetic fibers which leave the spinal cord with the anterior roots of the 

 upper thoracic nerves. These fibers pass to the sympathetic trunk through the 

 white rami communicantes and terminate in the superior cervical ganglion. Post- 

 ganglionic fibers from the superior cervical ganglion pass through the internal 

 carotid nerve and the ophthalmic division of the trigeminal nerve to the orbit 

 where the long ciliary nerves conduct the impulses to the eyeball and the dilator 

 pupillae muscle. The cell bodies of these preganglionic fibers are connected with 

 fibers which descend from the mid-brain. 



Other postganglionic fibers from the superior cervical ganglion are distributed as 

 secretory fibers to the salivary glands, the lacrimal glands and to the small glands 

 of the mucous membrane of the nose, mouth and pharynx. 



The thoracic sympathetics supply accelerator nerves to the heart. They are 

 supposed to emerge from the spinal cord in the anterior roots of the upper four or 

 five thoracic nerves and pass with the white rami to the first thoracic ganglion, 

 here some terminate, others pass in the ansa subclavia to the inferior cervical 

 ganglion. The postganglionic fibers pass from these ganglia partly through the 

 ansa subclavia to the heart, on their way they intermingle with sympathetic fibers 

 from the vagus to form the cardiac plexus. 



Inhibitory fibers to the smooth musculature of the stomach, the small intestine 

 and most of the large intestine are supposed to emerge in the anterior roots of the 

 lower thoracic and upper lumbar nerves. These fibers pass through the white rami 

 and sympathetic trunk and are conveyed by the splanchnic nerves to the pre- 

 vertebral plexus where they terminate in the collateral ganglia. From the celiac and 

 superior mesenteric ganglia postganglionic fibers (inhibitory) are distributed to the 

 stomach, the small intestine and most of the large intestine. Inhibitory fibers to 

 the descending colon, the rectum and Internal sphincter ani are probably post- 

 ganglionic fibers from the inferior mesenteric ganglion. 



The thoracolumbar sympathetics are characterized by the presence of numerous 

 ganglia which may be divided into two groups, central and collateral. 



The central ganglia are arranged in two vertical rows, one on either side of the 

 middle line, situated partly in front and partly at the sides of the vertebral column. 

 Each ganglion is joined by intervening nervous cords to adjacent ganglia so that 

 two chains, the sympathetic trunks, are formed. The collateral ganglia are found 

 in connection with three great prevertebral plexuses, placed within the thorax, 

 abdomen, and pelvis respectively. 



The sympathetic trunks (truncus sympathicus; gangliated cord) extend from the 

 base of the skull to the coccyx. The cephalic end of each is continued upward 

 through the carotid canal into the skull, and forms a plexus on the internal carotid 

 artery; the caudal ends of the trunks converge and end in a single ganglion, the 

 ganglion impar, placed in front of the coccyx. The ganglia of each trunk are dis- 

 tinguished as cervical, thoracic, lumbar, and sacral and, except in the neck, they 

 closely correspond in number to the vertebrae. They are arranged thus: 



Cervical portion .... ... 3 ganglia 



Thoracic " . 12 



Lumbar " 4 



Sacral 4 or 5 " 



In the neck the ganglia lie in front of the transverse processes of the vertebras; 

 in the thoracic region in front of the heads of the ribs; in the lumbar region on the 

 sides of the vertebral bodies; and in the sacral region in front of the sacrum. 



Connections with the Spinal Nerves. Communications are established between 

 the sympathetic and spinal nerves through what are known as the gray and white 

 rami communicantes (Fig. 799) ; the gray rami convey sympathetic fibers into the 

 spinal nerves and the white rami transmit spinal fibers into the sympathetic. 





