356 



THE MUSCLES AND FASCIA 



performed mainly by the flat muscles (Obliqui and Transversalis) of the abdomen, 

 assisted also by the Rectus. Other muscles of forced expiration are the Internal 

 intercostals and Triangularis sterni (as above mentioned). 



3. MUSCLES OF THE ABDOMEN. 



The muscles of the abdomen may be divided into two groups: 1. The super- 

 ficial muscles of the abdomen ; 2. The deep muscles of the abdomen. 



1. Superficial Muscles. 



The Muscles in this region are, the 



Obliquus Externus. Transversalis. 



Obliquus Internus. Rectus. 



Pyramidalis. 



Dissection (Fig. 217). To dissect the abdominal 

 muscles, make a vertical incision from the ensif'orm car- 

 tilage to the symphysis pubis ; a second incision from the 

 umbilicus obliquely upward and outward to the outer sur- 

 face 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 outward to the ante- 

 rior superior iliac spine, and along the crest of the ilium 

 as far as its posterior third. Then reflect the three flap* 

 included between these incisions from within outward, in 

 the lines of direction of the muscular fibres. If necessary, 

 the abdominal muscles may be made tense by inflating the 

 peritoneal cavity through the umbilicus. 



The Superficial fascia of the abdomen consists, 

 over the greater part of the abdominal wall, of a 

 single layer of fascia, which contains a variable 

 amount of fat ; but as this layer approaches the 

 groin it is easily divisible into two layers, be- 

 tween which are found the superficial vessels and 

 nerves and the superficial inguinal lymphatic 

 glands. The superficial layer (fascia of Camper) 

 is thick, areolar in texture, containing adipose 

 tissue in its meshes, the quantity of which varies 

 in diiferent subjects. Below it passes over Pou- 

 part's ligament, and is continuous with the outer 

 layer of the superficial fascia of the thigh. In the male this fascia is continued 

 over the penis and outer 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 muscular fibres. From the scrotum it may be traced 

 backward to be continuous with the superficial fascia of the perineum. In the 

 female this fascia is continued into the labia majora. The deeper layer (fascia of 

 Scarpa) is thinner and more membranous in character than the superficial layer. 

 In the middle line it is intimately adherent to the linea alba and to the symphysis 

 pubis, and is prolonged on to the dorsum of the penis, forming the suspensory 

 ligament ; above, it is continuous Avith 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. 218) 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 Avail, of the 



S. Dis- 

 section of 

 inguinal 

 hernia. 



FIG. 217. Dissection of abdomen. 



