412 



APPLIED ANATOMY. 



type, 93 or 94 per cent. , in which the outer side is much the larger, and the root of 

 the appendix is on the inner wall just below the ileocaecal valve (in the adult about 

 2 cm. y\ in.). 



The ileocsecal valve marks the emptying of the ileum into the large intestine. 

 On the surface of the body it corresponds to a point 2.5 cm. (i in.) below the 

 middle of a line joining the anterior superior spine and the umbilicus and the same dis- 

 tance above the middle of a transverse line drawn from the anterior superior spine to 

 the median line. This point is about on the linea semilunaris and directly above the 

 point where the external iliac artery passes under Poupart's ligament. Normally 

 the ileocaecal valve will allow of the passage of gas from the colon into the ileum, as 

 in Senn's hydrogen test for perforation, but not of liquids or solids. 



Vermiform Appendix (processus vermiformis). The appendix varies 

 much, both in length and diameter. In health its average length may be given as 



from 8.75 cm. (3^ in.) to 10 cm. (4 in. ) 

 and its diameter as 6 mm. (^ in.). It is 

 pale in color and soft in consistence, with 

 its blood-vessels barely visible. In disease 

 it becomes hard and red and the injected 

 vessels are distinctly seen. It becomes 

 much increased in diameter, equalling in 

 size a finger or thumb, and lengthens to 

 15 cm. (6 in. ) or even more. It possesses 

 a serous peritoneal coat, a longitudinal 

 muscular, a circular muscular, a submucous 

 and a mucous coat. The lumen of the 

 appendix has been found to be partially 

 occluded in at least one-fourth of all adults. 

 This occlusion occurring toward its distal 

 extremity is not regarded as pathological, 

 but constrictions occurring elsewhere in the 

 length of the tube are probably the result 

 of previous disease. 



The opening of the appendix in the 

 ciecuni is about 2. 5 cm. ( i in. ) below and 

 a little behind the ileocaecal opening. The 

 fold of mucous membrane guarding it has 

 been named the valve of Gerlach but it is 

 not generally regarded as a distinct valve. 

 The root of the appendix is only about 2 

 cm. (24 m - ) below the lower edge of the ileum and is often even closer on account 

 of the lower surface of the ilium being in contact with the caecum at that point. It 

 corresponds to a point on the surface of the body where the right semilunar line 

 crosses a line joining the two anterior superior spines (Fig. 423). 



The meso-appendix (mesenteriolum) comes off the lower surface of the 

 mesentery. It is snorter than the appendix, hence the twisting and curling of the 

 latter. It usually, but not always, extends to the tip and contains toward its left or 

 free border the append icular artery. 



The ileocolic artery, from the superior mesenteric, as it approaches the ileo- 

 caecal junction divides into five branches: (i) the colic, distributed to the colon; (2) 

 the Heal, to the upper surface of the ileum; (3) the anterior ilcoccecal branch, to the 

 front of the caecum, passing through the ileocolic fold; (4) the posterior ileoccecal 

 artery, to the posterior part of the caecum; (5) the appendicular artery. The appen- 

 dicular artery descends behind the ileum to enter the meso-appendix and, after sending 

 one recurrent branch to the root of the appendix and another to the ileocaecal fold, 

 passes along the left or free edge of the meso-appendix, and, if this is short, it may 

 be continued on the surface of the appendix to its extremity (Fig. 424). 



In removing the appendix this artery requires ligation and if the ligature is not 

 placed close to the root the recurrent branches will not be included and may cause 

 dangerous bleeding. 



Fir,. 423. The relations of the appendix. The 

 ileocaecal junction is seen to be about one inch below 

 the middle of a line joining the anterior superior 

 spine and umbilicus or where this line crosses the 

 linea semilunaris. The base of the appendix is under 

 the point of crossing of the linea semilunaris and the 

 middle of a horizontal line running from the anterior 

 superior spine to the mid-line of the body; it is one 

 inch below the ileoc;ecal junction. 



