THE ABDOMINAL CAVITY 313 



when the expulsive efforts fail and the stone falls back again 

 into the gall-bladder. 



As the centres for the stomach and the, gall-bladder occupy 

 the same segments in the spinal medulla, and since both 

 viscera are supplied by the vagus, the symptoms which are 

 due to viscero-sensory and viscero-motor reflexes are very 

 similar in the two cases. Thus in ulceration of the stomach 

 the stimulation of the gastric terminals of the vagus causes 

 vomiting on the ingestion of food. In diseases of the gall- 

 bladder the afferent impulses along the vagus may set up a 

 " focus of irritation " in the medulla oblongata, so that the 

 simple stimulus of the gastric branches of the same nerve, 

 caused by the ingestion of food into the healthy stomach, may 

 elicit an abnormal response from the irritated centre, and emesis 

 results. Errors in diagnosis, therefore, are not infrequent, and 

 are easily explained in the light of the nerve-supply of the two 

 viscera. 



The Fundus of the Gall-Bladder may be mapped out on 

 the surface in the angle between the right rectus and the costal 

 margin, with the patient in the supine condition. When the 

 gall-bladder becomes distended it enlarges downwards and 

 medially, giving rise to a movable tumour, which may be mistaken 

 for a floating kidney. Owing to its peritoneal connection to 

 the liver, the tumour always returns to its first position after 

 being displaced by manipulations, and this feature should suffice 

 to determine the diagnosis. 



The mucous membrane lining its interior is so rich in mucus- 

 secreting glands that, when the cystic duct is obstructed by an 

 impacted calculus, the gall-bladder may become dilated and form 

 a mucocele. This obstruction offers no hindrance to the free 

 passage of bile into the duodenum, and therefore cholecystitis 

 may be present without an associated jaundice. 



In the event of permanent occlusion of the bile-duct from 

 pancreatitis, malignant disease, or stricture, the intense jaundice 

 and the itching which it causes may be relieved by the operation 

 of cholecyst-enterostomy. If possible the duodenum is utilised, 

 but, failing it, good results follow the anastomosis of the gall- 

 bladder with the stomach, right colic flexure, or the transverse 

 colon. The operation is carried out on the same lines as gastro- 

 enterostomy or entero-anastomosis. 



The Cystic Duct is about i| inches long, but as it is folded 

 upon itself in an S-shaped manner, its union with the hepatic 



