1664 



HUMAN ANATOMY. 



croach upon the mucosa and its glands to reach almost the free surface. The layer 

 of circular muscular fibres is i mm. thick, or about twice the thickness of the lon- 

 gitudinal one. Both layers have interruptions, so that the submucous and subperi- 

 toneal layers are in places continuous. This occurs particularly along the insertion 

 of the fold of peritoneum called the mesentery of the appendix. 



The vermiform appendix (processus vermiformis) is a long, slender, worm- 

 like diverticulum from the caecum, formed of all the coats of the intestine. Its length 

 varies from i cm. (/3 in.) to 24 cm. (9/3 in.), the average being probably about 

 8.4 cm. 1 (3^ in.). Monks and Blake,' from the records of 641 autopsies at the 

 Boston City Hospital, give the average length as 7.9 cm. (3 in.), with the extremes 

 as above. Berry finds that the appendix is on the average about i cm. longer in 



FIG. 1416. 



Longitudinal muscle 



ular muscle 



Transverse section of vermiform appendix. X 



the male ; others find no particular difference. The diameter at the base is 6 mm. 

 and at the apex 5 mm. Its usual origin is from the postero-median aspect of the 

 caecum. According to Berry, this occurs in more than 90 per cent., the point of 

 origin being 1.7 cm. distant from the end of the ileum. This is very important as 

 showing ,i relatively fixed point of origin, as the general direction of the appendix is 

 very uncertain. That of the distal half especially is largely a matter of chance. 

 Men-over, the position after death is, except in certain cases, no guide to that 

 during life. The appendix is attached to the caecum and to neighboring structures 

 I'V .1 peritoneal fold to be described later. If this fold be long and narrow, the 

 movements of the appendix are much restricted ; if the base of the fold be short 

 and it> attachment to the appendix a long one, the appendix is thrown into coils. 



1 Fawrett and I'.latclifonl i for the average U-ngtln : Proceedings of the Anatomical Society 

 of ('.re. it P.ritam and Ireland, Journal of Anatoinv and Physiology, vol. xxxiv., 1900. 



1 P.oston Medical and Surgical Journal, November 27, 1902. 



