390 CLINICAL APPLIED ANATOMY. 



allow appendix suppuration to extend into the psoas sheath. The 

 hip-joint, over which the muscle passes, may be invaded, and the 

 elongated bursal space, which lies between the vastus interims 

 and the inner aspect of the femur, is sometimes infected, giving 

 rise to periostitis and necrosis, which may show itself in the 

 popliteal region. The pus may also be directed into the thigh 

 under the iliac fascia. Psoas abscess dependent upon caries is 

 described elsewhere. 



ABDOMINAL HEKNIA. 



An abdominal hernia is the protrusion of an abdominal viscus 

 from the abdominal cavity. As a rule such a hernia consists of 

 a sac, composed of peritoneum, and contents, which may be any 

 of the abdominal viscera. 



Except in quite rare instances there is no rupture or tearing 

 in the causation of a hernia, and therefore the term " rupture " 

 to designate this condition is not a scientific one. 



Certain anatomical peculiarities heighten the likelihood of a 

 protrusion at particular regions of the abdominal wall. These 

 may be termed weak spots. In addition to the area being a 

 weak one, from the want of the thickness of the structures in 

 the region, there is also the possibility of a congenital pouch of 

 peritoneum persisting after birth, into which viscera may 

 descend, and some believe that this finger-like process of serous 

 membrane is the most important factor in the production of a 

 hernia. 



The three common weak spots at which hernia most usually 

 protrude are the inguinal region, the femoral region, and the 

 umbilical region. All other hernia? are comparatively rare, and 

 will only be briefly alluded to. 



Inguinal Hernia. In the male the testis, accompanied by its 

 cord, passes from the abdomen into the scrotum. In the female 

 the round ligament of the uterus traverses the abdominal wall 

 and occupies the same position as the upper part of the spermatic 

 cord does in the male. A weak spot is therefore left in this 



