294 JoiRNAi. (IF CoMi'AKA'rnK Neuroi.ogy. 



two divisions, cephalic and caudal. The cephalic division, 

 the crti7-al branch (crur. ), bends around the lateral border of 

 the M. psoas, and 20 mm. peripherad of its origin it accom- 

 panies the ilio-lumbar artery into the transverse muscle. Its 

 course is caudad in the transverse and ectal muscles, and 

 leaves the pelvis by the ectal abdominal ring entad of Pou- 

 part's ligament; its course outside the pelvis is along the 

 ectal fascia over the caudal thigh to the knee, and terminates 

 in the integument of the proximal crus, where it joins fila- 

 ments of the external cutaneous nerve. The caudal or dorsal 

 divisiofz, the genital branch (gen.) lies upon the meso-ental 

 surface or border of the M. psoas, entad of the ilio-lumbar 

 artery, at which point it gives a large anastomotic branch to 

 the open plexus of nerves and vessels of that region, and 

 thence continues caudad in the ental muscle, to which it 

 gives several filaments. At the Poupart's ligament (Fig. P.) 

 it is reflected ventro-cephalad, and terminates in the integu- 

 ment of the hypogastric region; filaments from the point of 

 reflection extend to the integument over the pubes. (I have 

 not traced this nerve in the male.) 



X. CUTANEUS ECTALIS. 



The external cutaneous nerve (Ext. Cut.) has its ectal 

 origin by two roots; the cephalic root is a branch of the loop 

 (Fig. Loop) between the fifth and the sixth lumbar nerves; 

 the caudal root is a branch of the sixth nerve in common 

 with the caudal root of the genito-crural. The origin and 

 the distribution of the genito crural and the external cutane- 

 ous nerves indicate an intimate inter-relation. 



The course of the nerve lies ectad of the anastomotic 

 branch from the G. sympathicus to the sixth lumbar nerve; 

 it runs obliquely through the origin fibres of the M. psoas 

 and comes to superficial view at the mesal border of that 

 muscle at the point where the iliac artery lies apposed to the 

 aponeurosis of the M. psoas, about 20-30 mm. cephalad 

 of the ramus of the pubis. Exposure is readily made by 



