THIGH AND I. KG. 307 



every branch of this nerve. Now, as the anterior crural gives off the internal 

 and middle cutaneous nerves, it yet remains for us to find the external cutaneous 

 nerve. 



The External Cutaneous Nerve. This is a branch of the lumbar plexus. 

 You find its main trunk by cutting through the deep fascia just below the 

 anterior superior iliac spine. Its branches are to be traced out in a manner 

 similar to the others. The cutaneous nerves of the anterior region of the thigh, 

 above referred to, become cutaneous, in average, at the junction of the upper and 

 middle one-third of the thigh. They divide into many branches each, and 

 collectively supply with sensation the front, outer .and inner parts of the thigh, 

 as far as the knee. At this place they all communicate to form the plexus 

 patellae, above described. 



The student should remember that while the external cutaneous nerve is 

 usually given in the text-books as a separate nerve of the lumbar plexus, still, 

 physiologically and rationally this nerve must be considered as a divorced or 

 dismembered branch of the anterior crural or femoral nerve, for this reason : The 

 nerve-trunk that supplies muscles, supplies the skin over the muscle, even to the 

 fullest insertion. Now, the anterior crural nerve supplies the extensor group of 

 muscles on the anterior and outer part of the thigh, hence the external cutane- 

 ous belongs philosophically to the anterior crural nerve, being divorced therefrom. 

 Such cases will frequently be met. The small sciatic is the divorced cutaneous 

 part of the great sciatic nerve. 



The spermatic cord must be noticed in this section, on account of its 

 important relation to two nerves and two arteries. You will find the spermatic 

 cord emerging from the inguinal canal, by the external abdominal ring (Fig. 163). 

 From this time on it is a cutaneous structure, because it is in the superficial 

 fascia. With your scissors trace the cord into the scrotum, by cutting through 

 the skin and superficial fascia. On the front of the cord you will find a little 

 nerve, the ilio-inguinal ; behind the cord you find the genital branch of the genito- 

 crural nerve. These nerves come from the lumbar plexus. The ilio-inguinal 

 nerve supplies the side of the thigh and the scrotum ; the genital branch of the 

 genito-crural supplies the cremaster in the male, and is lost on the round liga- 

 ment in the female. The arteries in relation with the spermatic cord are the 

 superficial and deep external pudics, branches of the common femoral ; the former 

 is in front of the cord, the latter behind the cord. 



THE DEEP FASCIA OF THE THIGH AND LEG. 



In figure 210 the glistening structure, upon which the long saphenous vein 

 anil its tributaries rest, is the outer or circumferential part of the deep fascia of 

 the lower extremity. The internal or central part of the deep fascia is, conse- 

 quently, surrounded by the external. In looking at a well-filled comb of honey, 

 you see only a small part of the honey-comb the outside limiting part. If, 

 however, you extract the honey, then you can see and examine the interior cel- 

 lular arrangements ; in other words, you can examine the internal divisions of 

 the connective tissue or deep fascia of the honey-comb. It is just so in examin- 

 ing the internal parts of the deep fascia of the thigh or of any organ of the body. 

 The deep part of the deep fascia corresponds to the cellular-tissue spaces of the 

 honey-comb. The spaces are occupied, not by one substance, but by many. 

 Muscles, vessels, bone, nerves, fat, glands, and all the compounds which make 

 up the limb occupy large spaces, just as effectually shut off from one another as 

 is the honey in one cell separated from that in another in the comb. 



Physiological division of labor and differential assimilation cause grouping of 

 like compounds. This grouping of muscles takes place on the physiological 



