THE MUSCLES OF THE ABDOMINAL WALL. 



481 



aponeurotica inguinalis (O.T. conjoined tendon), which passes anterior to the inferior 

 part of the rectus muscle, to be inserted into the crest and tubercle of the pubis 

 and the ilio-pectineal line. - 



The transversus muscle is separated by the lower intercostal nerves from the 

 obliquus internus muscle, and is lined on its deep surface by the fascia transversal] s. 

 Its inferior border forms a concave edge, separated from the inguinal ligament by 

 a lunular interval in which the fascia transversalis appears, and through which the 

 spermatic funiculus emerges at the abdominal inguinal ring, under cover of the 

 obliquus internus muscle and the aponeurosis of the obliquus externus. 



OBLIQUUS EXTERNUS 

 ABDOMINIS 



^OBLIQUUS INTERNUS 

 ''ABDOMINIS 



Anterior superior 



iliac spine 



TRANSVERSUS 

 ABDOMINIS 



, OBLIQUUS INTERNUS 

 ABDOMINIS (reflected) 



Aponeurosis of obliquus 

 "externus (reflected) 

 Abdominal inguinal ring 



.^Spermatic funiculus and 

 infundibuliform fascia 

 Fascia transversalis 



_.Falx aponeurotica in- 

 guinalis 



.Fossa ovalis (O.T. saphen- 

 ous opening) ' 



Great saphenous vein 



FIG. 427. THE DISSECTION OF THE INGUINAL CANAL. 



The anterior muscles of the abdominal wall include the pyramidalis and rectus 

 abdominis, enveloped by the sheath of the rectus, on either side of the linea alba. 



M. Pyramidalis Abdominis. The pyramidalis abdominis is a small 

 triangular muscle arising from the pubic crest, anterior to the rectus muscle 

 (Fig. 428, p. 482). 



It is directed obliquely upwards, to be inserted, for a variable distance, into the 

 linea alba. The muscle is often absent. 



M. Rectus Abdominis. The rectus abdominis muscle is broad and strap- 

 like, and arises, by a medial and a lateral head, from the symphysis and crest of 

 the pubis (Fig. 428, p. 482). 



The muscle expands as it passes upwards, and is inserted, from medial to lateral 

 side, into the anterior surface of the xiphoid process (Fig. 428, p. 482), and into the 

 superficial surface of the seventh, sixth, and fifth costal cartilages. On its anterior 



32 



