1132 



SURGICAL AND TOPOGRAPHICAL A^ATOMY 



quadratum in the diaphragm, and the membranous urethra through the triangular 

 hgament. 



Effect of position of the thigh on the ring. — As the lower pillar is blended 

 with Poupart's ligament, and as the fascia lata is connected with this, movements 

 of the thigh will aifect tlie ring much, making it tighter or looser. Thus extension 

 and abduction of the thigh stretch the pillars and close the ring. In llexion and 

 adduction of the thigh the pillars are relaxed; and this is the position in which 

 reduction of a hernia is attempted. In flexion and aV)duction of the thigh, the ring 

 is open; and this is the position in Avhich a patient should sit, to try on a truss, 

 and cough. If the hernia is now kept up, the truss is satisfactory. 



Helping to protect this most important spot, and preventing its being more than 

 a potential ring, are not only the two pillars, and the intercolumnar fascia, but also 



Fig. 700. —The Parts coxcerxed ix Ixguixal Herxia. 

 (From a dissection in the Hunterian Museum.) 



External oblique, cut and turned back Internal oblique External oblique 



Trausveraalia 



Fascia 



transveraalia 



Common femoral 

 vessels 



Triangular fascia 



a structure which has been called a third or posterior pillar, namely, the triangular 

 fascia. This has its base above at the lower part of the linea alba, where it joins 

 its fellow and the aponeurosis of the external oblique, and its apex downwards and 

 outwards, where, having passed behind the internal pillar, it blends with Gimber- 

 nat's ligament. Again, the conjoined tendon of the internal oblique and trans- 

 versalis curving inwards and downwards to be attached to the ilio-pectineal line 

 and spine is a most powerful protection, behind, to what is otherwise a weak spot 

 and a potent ial ring. 



INGUINAL CANAL. — Tliis is not a canal in the usual sense, Init a chink or flat- 

 sided passage in the thickness of the alxlominal wall. Tlie descriptions of the 

 canal usually given apply rather to the diseased than to the healthy state. It was 

 a canal once, and for a time only, i.e. in the later months of fn^al life. It remains 

 weak for a long time after, but only a vestige of it remains in the well-made adult. 

 On the inner surface of the abdomen we have a few inconspicuous inguinal 



