OF THE ABDOMEN. 



359 



MUSCLES OF THE ABDOMEN. 



The muscles in this region are, the 



Obliquus Externus. 

 Obliquus Internus. 

 Transversalis. 



Kectus. 

 Pyramidalis. 

 Quadratus Lumborum. 



Fig. 229. Dissection of Abdomen. 



Dissection (Fig. 229). To dissect the abdominal muscles, make a vertical incision from the 

 ensiform cartilage to the pubes, a second incision from the umbilicus obliquely upwards and out- 

 wards to the outer surface of the chest, as high as the lower border of the fifth or sixth rib, and 

 a third, commencing midway between the umbilicus and pubes, transversely outwards to the 

 anterior superior iliac spine, and along the crest of the 

 ilium as far as its posterior third. Then reflect the three 

 flaps included between these incisions from within out- 

 wards, in the line of direction of the muscular fibres. If 

 necessary, the abdominal muscles may be made tense by 

 inflating the peritoneal cavity through the umbilicus. 



The External or Descending Oblique muscle 

 (Fig. 230) is situated on the side and fore part 

 of the abdomen ; being the largest and the most 

 superficial of the three flat muscles in this 

 region. It is broad, thin, and, irregularly quad- 

 rilateral, its muscular portion occupying the 

 side, its aponeurosis the anterior wall of the 

 abdomen. It arises, by eight fleshy digitations, 

 from the external surface and lower borders of 

 the eight inferior ribs; these digitations are 

 arranged in an oblique line running downwards 

 and backwards ; the upper ones being attached 

 close to the cartilages of the corresponding ribs; 

 the lowest, to the apex of the cartilage of the 

 last rib; the intermediate ones, to the ribs at 

 some distance from their cartilages. The five 

 superior serrations increase in size from above 

 downwards, and are received between corres- 

 ponding processes of the Serratus Magnus; the 

 three lower ones diminish in size from above 

 downwards, receiving between them corresponding processes from the Latissi- 

 mus Dorsi. From these attachments, the fleshy fibres proceed in various direc- 

 tions. Those from the lowest ribs pass nearly vertically downwards, to be 

 inserted into the anterior half of the outer lip of the crest of the ilium; the 

 middle and upper fibres, directed downwards and forwards, terminate in ten- 

 dinous fibres, which spread out into a broad aponeurosis. This aponeurosis, 

 joined with that of the opposite muscle along the median line, covers the whole 

 of the front of the abdomen : above, it is connected with the lower border of 

 the Pectoralis Major ; below, its fibres are closely aggregated together, and 

 extend obliquely across from the anterior superior spine of the ilium to the 

 spine of the os pubis and the pectineal line. In the median line, it interlaces 

 with the aponeurosis of the opposite muscle, forming the linea alba, and extends 

 from the ensiform cartilage to the symphysis pubis. 



That portion of the aponeurosis which extends between the anterior superior 

 spine of the ilium and the spine of the os pubis, is a broad band, folded inwards, 

 and continuous below with the fascia lata ; it is called Poupari's ligament. The 

 portion which is reflected from Poupart's ligament into the pectineal line is 

 called Gimbernat' 's ligament. 1 From the point of attachment of the latter to the 

 pectineal line, a few fibres pass upwards and inwards, beneath the inner pillar 



1 All these parts will be found more particularly described with the Surgical Anatomy of 

 Hernia. 



