448 THE MUSCLES AND FASCIA 



surface of the cord to the scrotum, where it helps to form the dartos. As it passes 

 to the scrotum it changes its character, becoming thin, destitute of adipose tissue 

 and of a pale reddish color, and in the scrotum it acquires some involuntary mus- 

 cular fibres. From the scrotum it may be traced backward to be continuous with 

 the superficial fascia of the perinseum. In the female this fascia is continued into 

 the labia majora. The deeper layer (fascia of Scarpa) is thinner and more mem- 

 branous in character than the superficial layer. In the middle line it is intimately 

 adherent to the linea alba ; above, it is continuous with the superficial fascia over 

 the rest of the trunk ; below, it blends with the fascia lata of the thigh a little 

 below Poupart's ligament ; and below and internally it is continued over the penis 

 and spermatic cord to the scrotum, where it helps to form the dartos. From the 

 scrotum it may be traced backward to be continuous with the deep layer of the 

 superficial fascia of the perinseum. In the female it is continued into the labia 

 majora. 



The External or Descending Oblique muscle (Fig. 292) 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 quadrilateral, 

 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 downward and backward ; 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 down- 

 ward, and are received between corresponding processes of the Serratus magnus ; 

 the three lower ones diminish in size from above downward, 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 downward, to be inserted into the anterior half of the outer lip 

 of the crest of the ilium ; the middle and'upper fibres, directed downward and for- 

 ward, terminate in tendinous fibres, opposite a line drawn from the prominence 

 of the ninth costal cartilage to the anterior superior spinous process of the ilium, 

 which then spread out into a broad aponeurosis. 



The Aponeurosis of the External Oblique is a thin, but strong membranous 

 aponeurosis, the fibres of which are directed obliquely downward and inward. It 

 is 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 linea ilio-pectinea. In the median line it interlaces with 

 the aponeurosis of the opposite muscle, forming the linea alba, which 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 inward, 

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

 portion which is reflected from Poupart's ligament at the spine of the os pubis 

 along the pectineal line is called Grimbernat's ligament. From the point of attach- 

 ment of the latter to the pectineal line, a few fibres pass upward and inward, 

 behind the inner pillar of the ring, to the linea alba. They diverge as they ascend, 

 and form a thin, triangular, fibrous band, which is called the triangular ligament 

 of the abdomen. 



In the aponeurosis of the External oblique, immediately above the crest of the 

 os pubis, is a triangular opening, the external abdominal ring, formed by a separa- 

 tion of the fibres of the aponeurosis in this situation. 



Relations. By its external surface, with the superficial fascia, superficial 

 epigastric and circumflex iliac vessels, and some cutaneous nerves ; by its internal 

 surface, with the Internal oblique, the lower part of the eight inferior ribs, and 



