

THE ABDOMEN. 171 



from the peritoneum by the transversalis fascia. The 

 rectus abdominis passes vertically down the abdominal 

 parietes, on either side of the linea alba, inclosed in a 

 partial sheath, and having three or four tendinous inter- 

 sections, which are very readily seen beneath the skin 

 when the muscle is in action. Below it is a little mus- 

 cle, the pyramidalis, attached below to the pubis and 

 inserted into the linea alba, at the junction of the middle 

 with the lower third of the rectus. The continuity of 

 the thin aponeurotic laminae, which exist between the 

 abdominal muscles, with the lumbar aponeuroses, ac- 

 counts for the occasional pointing of lumbar abscess in 

 the parietes above Poupart's ligament, or at the edge of 

 the rectus. The deep epigastric artery, with its veins, 

 after passing between the peritoneum and transversalis 

 fascia, gets behind it, and entering its fibres, freely 

 anastomoses with the superior epigastric from the inter- 

 nal mammary, which vessel itself enters the rectus below 

 the cartilages of the eighth or ninth ribs. Between the 

 transversalis fascia and the peritoneum is the subperi- 

 toneal cellular tissue. The peritoneum itself closely 

 lines this region of the abdominal wall, excepting for a 

 short distance above the pubes, where its attachment is 

 very lax a circumstance taken advantage of in punc- 

 ture of the bladder in this region. 



Operations for the removal of abdominal tumors and 

 for paracentesis abdominis are performed in the mesial 

 line, as the simple structure of the linea alba, present- 

 ing no layers, does not admit of infiltration into muscu- 

 lar aponeuroses or sheaths. In the operation of para- 

 centesis the parietal layer of the peritoneum only would 

 be involved ; but in operations on an ovarian cyst, for 

 example, both parietal and visceral are divided. In 



