THE THIGH 173 



thinning indicates the position of the lateral part of the margo falciformis, 

 which should be defined by the edge of the knife and then traced proxhnally 

 and medially into the cornu superius. When the lateral part of the margo 

 falciformis is displayed the dissector should return to the cornu inferius and 

 trace it to its fusion with the fascia pectinea ; then he should clear away 

 the superficial fascia from the surface of the latter. As he does this he 

 will recognise that, above the level of the cornu inferius, the fascia pectinea 

 does not pass across the front of the femoral vessels to join the iliac portion 

 of the deep fascia, but, on the contrary, it dips posterior to the femoral 

 vessels to become continuous with the deep intermuscular septa. In a 

 sense, therefore, the margo falciformis forms the medial free margin of 

 the iliac part of the fascia lata (see Fig. 65). In reality, however, a 

 thinner layer of fascia is continued from this margin across the front of 

 the sheath of the femoral vessels to join the fascia pectinea. This thinner 

 layer of fascia which closes the fossa is known as the fascia cribrosa, 

 because it is perforated by the great saphenous vein and by the efferent 

 vessels of the inguinal and subinguinal lymph glands on their way to join 

 the deep subinguinal lymph glands. 



When the margins of the fossa ovalis have been displayed, the inguinal 

 and subinguinal lymph glands and the fascia cribrosa should be removed, 

 care being taken, during the removal of the latter, to avoid injury to the 

 femoral sheath which lies subjacent to them. 



Fossa Ovalis (O.T. Saphenous Opening). This is the 

 aperture in the deep fascia through which the great saphenous 

 vein passes to its junction with the femoral vein. A thin 

 fascia, called the fascia cribrosa, is spread over the opening. 

 Difference of opinion exists as to what the fascia cribrosa 

 really is. It is regarded by some as being a part of the 

 superficial fascia, but it is more correct to look upon it as 

 being a thin layer of fascia lata carried over the opening, or, 

 in other words, a prolongation medially of the lateral margin 

 of the opening. 



The fossa ovalis is of special importance, because it is the 

 opening through which femoral hernia makes its way to the 

 surface. It is oval in shape and not more than half an 

 inch in width ; but it is at least one and a half inches long. 

 Its medial boundary, which is formed by the receding fascia 

 pectinea, lies on a deeper plane than the lateral boundary. 

 The lateral boundary or margo falciformis is crescentic. It 

 is formed by the iliac portion of the fascia lata. The cornu 

 inferius of the falciform edge curves medially, distal to the 

 proximal end of the great saphenous vein, to join the fascia 

 pectinea. The cornu superius (sometimes called Hey's liga- 

 ment), not so well defined, sweeps medially, anterior to the 

 proximal part of the femoral sheath, and joins the front 

 of the lig. lacunare (O.T. Gimbernat's ligament) (Fig. 65). 



