5i8 



HUMAN ANATOMY. 



lower three ribs, while of the rest the more anterior ones pass forward and upward, 

 those from the neighborhood of the anterior superior iliac spine directly forward, and 

 those from Poupart's ligament forward and downward, all joining in a fiat aponeu- 

 rosis which unites with the anterior abdominal aponeurosis at the linea semilunaris. 

 In its lowermost portion the aponeurosis unites with that of the transversalis to form 

 what is termed the conjoined tendo7i, and by this it is attached to the crest of the pubis. 



Fig. 524. 



Pectoralis major 



Serratus magnus — ' 



Latissimus dorsi 



Origin of pectoralis major 

 from slieath of rectus 



External oblique 



Pctit's triangle- 



^ 



Fascia lata 



Gluteus maximus 



Line of subcostal arch 



— Linea transversa 



Linea semilunaris 

 - Lmbilicus 



Linea alba 

 Anterior superior iliac spine 



Suspensory ligament of penis 

 Poupart's ligament 



Spermatic cord 



Dissection of lateral body-wall, showing external oblique and adjoining muscles 



Nerve-Supply. — From the anterior divisions of the eighth to the twelfth 

 thoracic nerves and from the ilio-hypogastric and ilio-inguinal nerves. 



Action. — The internal oblique acts very similarly to the external in compressing 

 the abdominal contents, in drawing the lower ribs downward, and in flexing the 

 thorax or pelvis laterally. It will also flex the thorax and vertebral column upon the 

 pelvis or the pelvis upon the vertebral column, but in these actions the accompanying 

 rotation will be in a direction contrary to that caused by the external oblique, the 

 thorax being rotated to the same side and the pelvis to the opposite side. It may be 

 remarked tlr.it the rotatory action of the external oblique of the one side and the 

 internal oblique of the other will be in the same direction. 



Variations. — The internal oblique may be crossed by one or more tendinous intersections 

 which have probably the same significance as those of the rectus abdominis. 



