i86. INFERIOR EXTREMITY 



pass behind the inguinal ligament into the canalis femoralis or most medial 

 ^compartment of the femoral sheath. The arrangement of the parts which 

 occupy the interval between the hip bone and the inguinal ligament 

 has been carefully considered, and the dissector should therefore be in a 

 position to understand how the occurrence of such a protrusion is rendered 

 possible. To the medial side of the femoral sheath the interval is closed 

 by the lacunar ligament, which, by its strength and firm connections, 

 constitutes an impassable barrier in this locality. To the lateral side of the 

 femoral sheath a hernial protrusion is equally impossible. There the fascia 

 transversalis on the anterior wall of the abdomen becomes continuous with 

 the fascia iliaca on the posterior wall of the abdomen, and along the line 

 of union both are firmly attached to the inguinal ligament. 



It is in the region of the femoral sheath, then, that femoral hernia takes 

 place. The three compartments of the sheath open above into the abdominal 

 cavity, but there is an essential difference between the three openings. The 

 two lateral, which hold the artery and the vein, are completely filled up by 

 their contents. The canalis femoralis, or most medial compartment, is not ; 

 it is much wider than is necessary for the passage of the fine lymph vessels 

 which traverse it. Further, its widest part is the upper opening or annuhis 

 femoralis. It has been noted that this is wide enough to admit the point of 

 the little finger, and it forms a weak point in the parietes of the abdomen ; 

 a source of weakness which is greater in the female than in the male, 

 seeing that in the former the distance between the iliac spine and the pubic 

 tubercle is proportionally greater, and in consequence the annulus femoralis 

 wider. Femoral hernia, therefore, is more common in the female. 



When attempts are made to reduce a femoral hernia, it is absolutely 

 necessary that the course which the protrusion has taken should be kept 

 constantly before the mind of the operator. In the first instance it descends 

 for a short distance in a perpendicular direction. It then turns forward 

 and bulges through the fossa ovalis. Should it still continue to enlarge, 

 it bends upwards over the inguinal ligament, and pushes its way laterally 

 towards the anterior superior spine of the ilium. The protrusion is thus 

 bent upon itself, and if it is to be reduced successfully it must be made 

 to retrace its steps. In other words, it must be drawn distally, and 

 then pushed gently posteriorly and upwards. The position of the limb 

 during this procedure must be attended to. When the thigh is fully 

 extended and rotated laterally all the fascial structures in the neighbour- 

 hood of the canalis femoralis are rendered tight and tense. When the 

 limb is flexed at the hip-joint and rotated medially, on the other hand, the 

 cornu superius of the margin of the fossa ovalis, and even the lacunar 

 ligament, are relaxed. This, then, is the position in which the limb 

 should be placed during the reduction of the hernia. 



As the hernia descends it carries before it the various layers which it 

 meets in the form of coverings. First it pushes before it the peritoneum, 

 and this forms the hernial sac. The other coverings from within outwards 

 are (i) the septum femorale ; (2) the wall of the femoral sheath (if it does 

 not burst through one of the apertures in this) ; (3) the fascia cribrosa ; 

 (4) and lastly, the superficial fascia and skin. 



The femoral canal, as we have noted, is surrounded by very unyielding 

 structures. Strangulation in cases of femoral hernia is therefore a matter of 

 very common occurrence. The sharp base of the lacunar ligament and 

 the superior cornu of the' margin of the fossa ovalis are especially apt to 

 bring about this condition. 



Abnormal Obturator Artery. The account of the surgical anatomy 

 of femoral hernia cannot be complete without mention of the relation 

 which the obturator artery frequently bears to the annulus femoralis. In 



