316 SURGICAL APPLIED ANATOMY. [Chap. xvi. 



sui-face through the triangle of Petit (the gap between 

 the latissimus dorsi and external oblique muscles), and 

 therefore just above the highest point of the iliac 

 crest. The sac must either force before it, or (in cases 

 of injury) come through the fascia lumborum and 

 internal oblique muscles, since those structures form the 

 floor of the triangle. Macready (Lancet, Nov. 8th, 

 1890) has collected twenty -five examples of this hernia. 

 Diaphragmatic hernice may be congenital or acquired. 

 The former variety is by far the more common, and is 

 due to simple arrest in the development of the dia- 

 phragm and persistence of the original connection 

 between the thorax and abdomen. The acquired form 

 usually follows a laceration of the diaphragm from 

 injury. In any case some of the abdominal viscera are 

 protruded, through the gap in the midriff, into the 

 thoracic cavity. Owing to the presence of the liver on 

 the right side, these hernise are much more common 

 on the left side. Of the organs, the stomach is the 

 most frequently dislodged, then the transverse colon, 

 omentum, small gut, spleen, liver, pancreas, and 

 kidneys in the order named (Leichtenstern). The 

 hernia may escape through the foramen for the gullet, 

 but never through that for the vena cava, nor through 

 the hiatus aorticus. The parts commonly selected are 

 the connective tissue intervals between the sternal and 

 costal origins of the diaphragm in front and its verte- 

 bral and costal origins behind. These hernia? are 

 more common in males. 



Posterior abdominal parictes. The lateral 

 and posterior walls of the abdomen are lined inside with 

 two fasciae, the transversalis and iliac. The transversalis 

 fascia lines the whole of the transversalis muscle, and is 

 much thicker below than above. Above it joins the 

 fascia covering the diaphragm, while below it is at- 

 tached to the iliac crest, and to the whole of Poupart's 

 ligament, save at that spot where it passes into the 



