THE ABDOMINAL WALLS 



247 



above. This margin is usually fused with the underlying trans- 

 versalis fascia, which is in direct contact with the rectus ab- 

 dominis in the lower part of the abdominal wall. 



Little difficulty is experienced in freeing the rectus abdominis 

 from the posterior wall of the sheath, but the muscle is much 

 more firmly adherent to the anterior wall, especially opposite 

 the lineae transversse. 



FIG. 75. Diagram of Transverse Sections through the Rectus Abdominis 

 Muscles, to illustrate the method of closing wounds in the infra-umbilical 

 part of the linea alba. 



I. The dotted line indicates the incision in the linea alba. 



II. Prior to closure of the median wound, an incision has been made on each side 

 into the anterior wall of the sheath. 



III. Closure of the median wound. The deepest suture includes the cut edges of the 

 parietal peritoneum as well as the sheath. The two recti and the anterior walls of their 

 sheaths may be united by one continuous suture and not by two layers of sutures as 

 shown in the figure. 



Incisions in the Abdominal Wall. Vertical Incisions 

 through the linea alba have several advantages, (i) They 

 are almost bloodless. (2) No muscle fibres are cut across. (3) 

 No nerves are injured. (4) They give access to both sides of 

 the abdomen. 



When the linea alba and the subjacent fascia transversalis 

 have been incised, the extra-peritoneal fat is exposed. This is 

 a thin layer inferiorly, but it is much thicker above the umbilicus. 



Owing to the close approximation of the recti below the 

 umbilicus there is very little tendency for ventral hernia to occur 

 after incisions through the lower part of the linea alba, but 

 vertical incisions through the supra-umbilical part of this line 



