ABDOMEN. 



229 



(4) the spermatic cord with the genital branch of the genito-crural nerve on its 

 posterior surface and the ilio-inguinal nerve in front; (4) you will see also with 

 the above abdominal intercostal nerves some small arteries. They are the lower 

 intercostals and lumbars. 



The nerves you see near the mid-line (Fig. 158) are the terminal branches, 

 while those represented more externally are the lateral cutaneous branches of the 

 intercostals. Search in the fat until you find the point of emergence of the nerve ; 

 then trace out its branches by dividing the connective tissue in the direction of 

 the branches. 



External Oblique (Fig. 159). (i) Dissect the fat and fascia off and expose 

 the muscle as in the figure. At the upper part of the muscle develop the digi- 

 tations of this muscle with the serratus magnus. Trace each digitation to the 

 bone. In developing these origins use the forceps and scissors. (2) Now trace 



Aponeurosis 

 of obliquus 

 externua 



Loops of | 

 eremaster 



Intercolumnar 

 fibres 



FIG. 161. OBLIQUUS EXTERNUS AND FASCIA LATA. 



the muscle downward and forward in the direction of the fibres to the outer lip 

 of the iliac crest. Notice that the muscular fibres disappear at the anterior 

 superior iliac spine, and from this point onward to the mid-line of the abdomen, 

 and downward to the pubes, the muscle is continued as an aponeurosis /. e., 

 the muscle minus the lean meat ! (3) Remove the fat and fascia, and demon- 

 strate the linea semilunaris, the lineae transversae, and the linea alba. The last 

 is in the mid-line. (4) Examine the lower margin of the aponeurosis of this 

 external oblique muscle. It extends in a sagging manner from the anterior 

 superior iliac spine to the pubic spine under the name of Poupart's ligament, or 

 crural arch. This arch is continuous below with the fascia lata of the thigh. 

 (5) Locate the spine of the pubes, and on the under part of the same find the 

 spermatic cord. (Fig. 161.) Trace this cord upward and outward to a point 

 where it enters the external abdominal ring. (Fig. 161.) Above and below the 

 ring, see the pillars or columns of the ring. Notice and develop some transverse 



