366 CLINICAL APPLIED ANATOMY. 



of a wheel across the abdomen, whereby this portion of the bowel 

 is subjected to a shearing force. Being fixed on the front of the 

 spine, it cannot slip away, and is lacerated. The rent may be 

 entirely extraperitoneal. 



Malignant disease of the small intestine is rare. When a 

 distinct tumour is present, and this is more likely to be the case 

 with sarcoma than with carcinoma, the length of the mesentery 

 may allow the growth to gravitate towards the lower part of the 

 abdomen. It may become adherent in this position, and by 

 ulceration a fistulous communication may be established with 

 some part of the colon, the urinary bladder, or other hollow 

 viscus. Pedunculated growths in the interior of the jejunum 

 or ileum sometimes give rise to extensive chronic intussusceptions, 

 an occurrence which is favoured by the length and freedom of 

 the mesentery. 



Malignant disease of the colon usually occurs in the form 

 of an annular carcinomatous infiltration leading to stricture. 

 Occasionally it is in the form of a tubular infiltration. In both 

 cases the interior, being exposed to the passage of the bowel 

 contents, tends to ulcerate and become septic. Malignant disease 

 is prone to arise in those parts of the colon which present abrupt 

 bends or are exposed to pressure by bony edges. It is often 

 met with on the brim of the true pelvis, or opposite the crest 

 of the ilium ; it is less common at the splenic or hepatic flexures, 

 in the transverse colon or the caecum. (Fig. 49, p. 362.) 



The growth opposite the brim of the true pelvis lies at the 

 junction of the iliac and pelvic portions of the colon. It may 

 become adherent to the left iliac vein, causing oedema of the left 

 leg, or compress the left ureter, giving rise to left renal colic 

 and hydronephrosis. Since the ovarian fossa and ovary are 

 close by, it is not surprising that the growth may become 

 adherent to the latter. Haemorrhoids may occur from obstruc- 

 tion to the veins in the bowel wall. Perforation at the site of 

 the growth will give rise to a pelvic abscess or a spreading general 

 peritonitis. 



The growth opposite the iliac crest on the left side occurs at 



