APPENDICITIS. 381 



presumably owing to paralysis of the gut induced by increasing 

 inflammation. The occurrence of deep-seated local pain in 

 appendicitis indicates inflammation of the sensitive parietal 

 peritoneum or retroperitoneal tissues. Absence of this deep 

 tenderness may be of serious prognostic import, indicating a 

 profound toxemia. Cutaneous hyperaesthesia, if present, for 

 it is exceptional, corresponds in distribution to the tenth, eleventh, 

 and twelfth dorsal segmental areas. It is a true reflected 

 tenderness, and is not derived from the visceral peritoneum, 

 which appears to be unable to originate sensory impulses. 



The mass which is felt in the abdomen in cases of appendicitis 

 may consist of inflamed caecum and small intestine, the appendix 

 itself, inflamed omentum, enlarged glands, faecal matter, and 

 pus. The disposition of the great omentum over the front of 

 the intestinal coils accounts for the frequency with which it 

 forms part of the wall of an appendix abscess. 



Venous thrombosis may arise as a complication of appendicitis. 

 The veins of the appendix are radicles of the portal system, and 

 may be the starting-points of portal thrombosis or portal 

 pyaemia. The proximity of the appendix to the right iliac veins, 

 across which it may lie, sometimes leads to thrombosis or 

 infection of these vessels, and in such cases thrombosis of the 

 right femoral vein, extension of clot to the opposite common iliac 

 vein, systemic pyaemia or pulmonary embolism, are dangers to be 

 feared. 



Arteries are rarely eroded during the course of the inflamma- 

 tion. If they are, haemorrhage into the peritoneal cavity or into 

 the bowel may occur. The right iliac arteries, the deep circumflex 

 iliac, and the colic branches in the wall of the gut have been 

 known to be the source of haemorrhage in such cases. 



The tracks followed by the pus when suppuration is localised 

 and intraperitoneal, or becomes extraperitoneal, are described 

 subsequently. (See page 383.) 



In the attempt to avoid hernia as a sequel to operations on 

 the appendix, advantage is taken of the arrangement of the 

 muscular layers of the abdominal wall. The rectus sheath may 



