THE ABDOMINAL WALLS 237 



THE ABDOMEN AND PELVIS. 



THE ABDOMINAL WALLS. 



Surface Landmarks. The Costal Margins, formed by the 

 cartilages of the tenth, ninth, eighth, and seventh ribs (the 

 last named being the lowest pair to reach the sternum), pass 

 upwards and medially towards the sides of the xiphoid process 

 and enclose between them the Subcostal Angle. The xiphoid 

 process lies in the depression at the apex of this angle, and its 

 pointed lower end is sometimes bent forwards, being then easily 

 palpable beneath the skin. 



The Iliac Crest forms the lower limit of the lateral aspect of 

 the abdominal wall. It can be traced forwards to the Anterior 

 Superior Spine, which lies on the same level as the second sacral 

 vertebra. About 2 inches behind this point, a prominent 

 tubercle can be felt on the outer lip of the crest ; it is utilised 

 in mapping out the regions of the abdomen. 



The fold of the groin extends downwards and medially from 

 the anterior superior spine to the tubercle (spine) of the pubis. 

 It overlies the inguinal ligament (of Poupart), which is slightly 

 convex downwards owing to the traction exerted on it by the 

 fascia lata of the thigh. This traction is transmitted by the 

 ligament to the lateral abdominal muscles, which are attached 

 to it, and renders them slightly tense when the thighs are 

 extended. In the examination of the abdomen, it is ad- 

 vantageous that the muscles should be relaxed as far as 

 possible, and to overcome the traction of the fascia lata, the 

 patient's legs are drawn up, flexing both the hip and the knee- 

 joints. This is the posture which is naturally assumed when 

 there is much distension of the abdomen, since it allows the 

 maximum amount of relaxation of the abdominal parietes. 



The highest point on the iliac crest lies on a level with the 

 lower part of the body of the fourth lumbar vertebra. In 

 subjects with firm abdominal muscles, the umbilicus also 

 corresponds to this level, but in obese subjects with lax ab- 

 dominal parietes, it may sink down to a lower plane. 



A linear furrow can be seen, in muscular subjects, in the 

 middle line of the anterior abdominal wall. It corresponds to 



