DESCENT OF HERNIA. 



837 



femoral canal. The septum ' crurale is perforated by numerous apertures for 

 the passage of lymphatic vessels, connecting the deep inguinal glands with those 

 surrounding the external iliac artery. 



Variations in Origin and Course of Obturator Artery. 

 Fig. 453. Fig. 454. 



The size of the femoral canal, the degree of tension of its orifices, and, con- 

 sequently, the degree of constriction of a hernia, varies according to the position 

 of the limb. If the leg and thigh are extended, abducted, or everted, the 

 femoral canal and its orifices are rendered tense, from the traction on these 

 parts by Poupart's ligament and the fascia lata, as may be ascertained by pass- 

 ing the finger along the canal. If, on the contrary, the thigh is flexed upon the 

 pelvis, and, at the same time, adducted and rotated inwards, the femoral canal 

 and its orifices become considerably relaxed ; for this reason, the limb should 

 always be placed in the latter position when the application of the taxis is made 

 in attempting the reduction of a femoral hernia. 



The septum crurale is separated from the peritoneum by a quantity of loose 

 subserous areolar tissue. In some subjects, this tissue contains a considerable 

 amount of adipose substance, which, when protruded forwards in front of the 

 sac of a femoral hernia, may be mistaken for a portion of omentum. 



Descent of the Hernia. From the preceding description it follows, that the 

 femoral ring must be a weak point in the abdominal wall ; hence it is, that when 

 violent or long-continued pressure is made upon the abdominal viscera, a por- 

 tion of intestine may be forced into it, constituting a femoral hernia ; and the 

 changes in the tissues of the abdomen which are produced by pregnancy, to- 

 gether with the larger size of this aperture in the female, serve to explain the 

 frequency of this form of hernia in women. 



When a portion of intestine is forced through the femoral ring, it carries 

 before it a pouch of peritoneum, which forms what is called the hernial sac ; ib 

 receives an investment from the subserous areolar tissue, and from the septum 

 crurale, and descends vertically along the crural canal in the inner compartment 

 of the sheath of the femoral vessels as far as the saphenous opening: at this 

 point, it changes its course, being prevented from extending further down the 

 sheath, on account of the narrowing of the sheath and its close contact with the 

 vessels, and also from the close attachment of the superficial fascia and crural 

 sheath to the lower part of the circumference of the saphenous opening ; the 

 tumor is, consequently, directed forwards, pushing before it the cribriform fascia, 

 and then curves upwards on to the falciform process of the fascia lata and lower 

 part of the tendon of the External Oblique, being covered by the superficial 

 fascia and integument. While the hernia is contained in the femoral canal, it 

 is usually of small size, owing to the resisting nature of the surrounding parts; 

 but when it has escaped from the saphenous opening into the loose areolar tissue 

 of the groin, it becomes considerably enlarged. The direction taken by a femoral 

 hernia in its descent is at first downwards, then forwards and upwards; this 

 should be borne in mind, as in the application of the taxis for the reduction of 

 a femoral hernia, pressure should be directed in the reverse order. 



Coverings of the Hernia. The coverings of a femoral hernia from within out- 



