OF THE ABDOMEN. 



281 



MUSCLES OF THE ABDOMEN. 



The muscles in this region are the 



Obliquus Externus. 

 Obliquus Internus. 

 Transversalis. 



Eectus. 

 Pyramidalis. 

 Quadratus Lumborum. 



Fig. 162. Dissection of Abdomen. 



Dissection (fig. 162). To dissect the abdominal muscles, a vertical incision should be made 

 from the ensiform cartilage to the pubes ; a second 

 oblique incision should extend from the umbilicus 

 upwards and outwards 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, should pass transversely 

 outwards to the anterior superior iliac spine, and 

 along the crest of the ilium as far as its posterior 

 third. The three flaps included between these 

 incisions should then be reflected 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 Oblique Muscle (fig. 163), 

 so called from the direction of its fibres, 

 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, irregu- 

 larly quadrilateral in form, its muscular 

 portion occupying the side, its aponeurosis 

 the anterior wall of that cavity. It arises, 

 by eight fleshy digitations, from the ex- 

 ternal surface and lower borders of the 

 eight inferior ribs; these digitations are 



arranged in an oblique line runniog downwards and backwards, the upper ones 

 being attached close to the cartilages of the corresponding ribs, the lowest to the 

 apex oFlihe 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 corresponding processes of the Ser- 

 ratus magnus ; the three lower ones diminish in size from above downwards, 

 receiving between them corresponding processes from the Latissimus dorsi. 

 From these attachments, the fleshy fibres proceed in various directions. 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 tendinous 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 pec- 

 tineal 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 Pouparfs ligament. The 

 portion which is reflected from Poupart's ligament backwards and inwards into the 

 pectineal line is called Gimbernafs ligament. From the point of attachment of 



