454 A MANUAL OF ANATOMY. 



DISSECTION. 



Raise the rectus from its sheath, beginning at its inner margin. The 

 deep epigastric artery will be seen entering the posterior part of the muscle 

 from below and the superior epigastric from above. The deep artery is a 

 branch of the external iliac, and the latter, of the internal mammary. They 

 anastomose in the substance of the rectus and form the longest arterial anas- 

 tomosis in the body 



Divide the deep epigastric as it enters the muscle, cut the nerves at the 

 outer border of the muscle, and the muscle itself at its middle. Reflect the 

 two portions. 



The posterior part of the sheath of the rectus can now 

 be seen. The upper three-fourths is formed by the apo- 

 neurosis of the transversalis with one-half of the internal 

 oblique, and ends below in a free border, called the semi- 

 lunar fold of Douglas, midway between the umbilicus and 

 the symphysis, or at the junction of the upper three-fourths 

 with the lower one-fourth of the rectus. The lower one- 

 fourth is formed by the transversalis fascia. 



DISSECTION. 



Cut through the transversalis from the fold of Douglas to the anterior 

 superior iliac spine, saving the iliohypogastric and inguinal nerves. This 

 gives below a triangular flap consisting of the fibres of the transversalis and 

 internal oblique attached by the conjoined tendon and Poupart's ligament. 



The posterior part of the rectus sheath is to be divided along the linea alba 

 to the ensiform, then the transversalis and overlying muscles removed entirely 

 from their attachments to the ribs, ilium, and lumbar fascia. The peritoneum 

 must not be perforated in this separation. To succeed in this will take some 

 time and patience. 



In reflecting the lower triangular flap do not take up the fascia transversalis, 

 which is closely united to the muscle, but is distinct from it. 



The Fascia Transversalis. Fig. 94. 



This is a layer of condensed connective tissue interposed 

 between the transversalis muscle and the extraperitoneal 

 tissue. It is thin in the upper region of the abdomen 

 where it becomes continuous w r ith the fascia covering the 



