462 A MANUAL OF ANATOMY 



ligament. External. — ^The upper extremity of the internal septum 

 within the femoral sheath. 



Normal Relation of Bloodvessels to the Femoral Ring — Anterior. — 

 The pubic branch of the deep epigastric artery, as it courses 

 inwards behind the inner half of Poupart's ligament. Supero- 

 anterior. — ^The vessels of the spermatic cord in the male, or of the 

 round ligament of the uterus in the female. Supero-external. — ^The 

 deep epigastric vessels. External. — ^The femoral vein, becoming 

 the external iliac vein, and separated from the ring by the upper 

 extremity of the internal septvmi within the femoral sheath. 



There are normally no vessels behind the ring, nor internal to 

 it. Under no circumstances are there ever any vessels behind it, 

 but in certain cases there may be a vessel on its inner side, namely, 

 an abnormal obturator artery. 



Abnormal or Aberrant Obturator Artery. — The obturator, artery normally 

 arises from the anterior division of the internal iliac, and under these circum- 

 stances it has no relation to the femoral ring. In about 30 per cent, of cases, 

 however, the obturator arises from the deep epigastric artery near its com- 

 mencement. This origin is more common in the female than in the male, 

 and is rarely bilateral. In most of these cases the aberrant obturator passes 

 backwards close to the inner side of the commencement of the external iliac 

 vein, and therefore upon the outer side of the femoral ring. In a few cases 

 the aberrant vessel passes backwards across the centre of the femoral ring. 

 In very rare cases it passes inwards behind Poupart's ligament, and then 

 arches backwards either close to the base of Gimbernat's ligament, or a line 

 or two inwards from it, and therefore upon the inner side of the femoral ring. 

 If a femoral hernia should occur under these latter circumstances, the aberrant 

 obturator artery would lie upon the inner side of the neck of the sac, and it 

 would thus be endangered in the operation for the reUef of the strangulation. 

 This very rare position of an aberrant obturator artery is more frequent in 

 the male than in the female, and, according to Lawrence, it occurred once in a 

 hundred cases. 



The origin of an aberrant obturator artery from the deep epigastric is due 

 to a more or less complete obliteration of a normal obturator at its origin, 

 and an enlargement of the normal anastomosis which takes place between 

 the pubic branches of the deep epigastric and obturator arteries behind the 

 body of the os pubis. 



Femoral Hernia. — This is a protrusion of an abdominal viscus, or part of a 

 viscus, through the crural or femoral ring. The course of the hernia is as 

 follows: entering the crural ring by elongating the septum crurale, it descends 

 through the femoral canal, on reaching the lower end of which it is placed in 

 the upper part of the saphenous opening, immediately below the falciform 

 process of Burns or femoral ligament of Hey. This structure now 

 impresses upon the hernia the following change in its course: the front 

 part of the hernia being arrested in its downward course by that structure. 

 the posterior part, which is free, comes down, and, passing forwards, turns 

 upwards upon the anterior abdominal wall, or upwards and outwards, 

 along Poupart's ligament. The course of a femoral hernia, when com- 

 plete, is thus at first downwards through the femoral ring and femoral canal, 

 then forwards through the upper part of the saphenous opening, and finally 

 either upwards or upwards and outwards. 



Coverings of a Femoral Hernia. — The coverings, from within outwards, are 

 as follows: 



1. Peritoneum, which forms the sac. 



2. Septum femorale. 



