EECTUM. 



1225 



Its general direction is downwards, but this varies at its two extremities, being 

 downwards and backwards above, downwards and strongly forwards below. 



Curvatures. The rectum is far from straight, notwithstanding its name, 

 for it is curved in both the an tero- posterior and the transverse planes. 

 Viewed from the side, it forms a gentle curve, with the convexity posteriorly, 

 which extends from the beginning of the rectum to the back of the 

 prostate, and fits into the hollow of the sacrum and coccyx (flexura sacralis). At 

 the back of the prostate a second curve (flexura perinealis) is formed where the rectum 

 joins the anal canal. The convexity of the perineal flexure is directed forwards, 



Lateral inflexions 



TTuper rectal val 



Ureter (cut) 



Vesicula seminalis 



Ductus deferens 



,,. Pudendal venous 

 plexus 



White line of pelvic fascia 



* Levator ani 

 Outline of empty urinary bladder 



Urethra 



Base of prostate 



FIG. 960. DISTENDED KECTUM IN SITU. 



>m a formalin -hardened male body, age 56. The peritoneum and extra-peritoneal tissue were removed, after 

 the pelvis had been sawn along a plane passing through the superior part of the symphysis pubis in front 

 and the lower part of the second sacral vertebra behind. The bladder, which was empty and contracted, 

 has also been removed, but its form is shown by a dotted line. The rectum was very much distended, 

 and almost completely occupied the pararectal fossse. 



whilst its concavity embraces the ano-coccygeal body the mass of muscular and 

 connective tissue which lies between the tip of the coccyx and the anal canal. 



When vieived from the front the rectum is seen to be regularly folded from side 

 to side in a zigzag fashion, the folding being slightly marked when the rectum is 

 empty, but becoming much more distinct with distension (Figs. 960 and 961). In 

 other words, when viewed from this aspect it presents, in the majority of cases, three 

 more or less distinct lateral flexures or inflexions. Of these the upper and lower 

 have their concavities directed to the left as a rule; the third flexure, which is the 

 best marked, lies between the other two, but on the right side. Not infrequently, 

 however, two are found on the right and one on the left side. The flexures, which 



