CHAP. XII.] SYMPATHETIC MOTIONS. 389 



the uterus in connexion with the early stage of pregnancy, causes 

 similar pains in the nerves of the thighs. 



Headache and defective vision are frequently produced by disor- 

 dered stomach. A draught of very cold water, or ice, taken quickly 

 into the stomach, may occasion acute pain in the course of either 

 frontal nerve. This same nerve on one side is frequently the seat of 

 pain after the imprudent use of acid wines or other fermented liquors. 



Movements, excited by the operation of a stimulus applied at a 

 distance, form a large proportion of the instances of sympathetic 

 phenomena. All the ordinary physical nervous actions in which 

 motions are excited by stimulating a sentient surface, may be re- 

 garded as examples of sympathetic actions.* The contraction of 

 the iris upon the application of the stimulus of light to the retina, 

 or of the pharyngeal muscles by stimulating the mucous membrane 

 of the fauces, are instances in point, where the stimulus acts indi- 

 rectly upon the contracting fibre. Nothing is more sure than that 

 in these instances the change wrought by the stimulus in certain sen- 

 tient nerves travels by a circuitous route through a nervous centre to 

 the muscles which are called into action. Akin to these actions are 

 the forcible respiratory movements which may be excited by irrita- 

 tion of the tracheal membrane, as coughing ; or sneezing, by stimu- 

 lating the nasal membrane ; or vomiting, by irritating the fauces. 

 Spasmodic affections are often instances of morbid actions in sym- 

 pathy with intestinal irritation, or the irritation of teething in 

 children. Partial or general convulsions are very frequently due to 

 either or both these causes. We have known the most violent 

 opisthotonos coexisting for a considerable time with the presence of 

 lumbrici in the intestine ; but ceasing immediately on the removal 

 of the worms. Vomiting is commonly sympathetic of diseased 

 kidney, or of the passage of a calculus along the ureter ; or it may 

 be induced by the introduction of a catheter into the urethra. Irri- 

 tation of the intestines, as in cholera, causes cramps of the most 

 violent kind in the lower extremities and abdominal muscles. The 

 contractions of the abdominal muscles in parturition, although 

 materially aided by the will, are in consent with the expulsive 

 efforts of the uterus. 



* It has been remarked, that the term " sympathetic actions''' involves a con- 

 tradiction. But it may be observed, that the contraction of the muscles, on which 

 the action depends, is only the natural mode in which that class of vital organs 

 can manifest their consent with certain states of nervous centres, or of sensi- 

 tive nerves. The action is the result of the state which the muscle assumes 

 in sympathy with the stimulated nerve. The contradiction is therefore appa- 

 rent not real. 



