602 THE LUMBAR ^'ERVES. 



second lumbar nerve, but receives also a fe^ fibres from the con- 

 necting cord between that and the first nerve. The nerve descends 

 obliquely through the psoas muscle, and afterwards on its fore 

 part, towards Poupart's ligament, dividing at a variable height into 

 an internal or genital, and an external or crural branch. It often 

 bifurcates close to its origin from the plexus, in which case its two 

 branches perforate the psoas muscle in ditt'erent places. 



(n) Tlie genital branch (external spermatic, Schmidt) lies upon or near the ex- 

 ternal iliac arterj', and sends filaments along that vessel ; then perforating the 

 transversalis fascia, it passes through the inguinal canal with the spermatic cord, 

 and is lost upon the cremaster muscle. In the female it accompanies the round 

 ligament of the utems. 



{h) The crural hranch (lumbo-inguinal nerve. Schmidt) descends upon the 

 psoas muscle beneath Pouparfs ligament into tlie thigh. Immediately below 

 that ligament, and at the outer side of the femoral artery, it pierces the fascia 

 lata, and supplies the skin on the upper part of the thigh, communicating with 

 the middle cutaneous branch of the anterior crural nei^ve. WTailst it is passing 

 beneath Poupart's ligament, some filaments are prolonged from this nerve on the 

 femoral artery. It is stated by Schmidt, that when the crural branch of the 

 genito-crural nerve is large, and commences near the plexus, he has observed it to 

 give a muscular branch to the lower border of the internal oblique and transver- 

 salis muscles. 



External cutaneous nerve. 



This nerve, commencing from the loop formed between the second 

 and third lumbar nerves, on emerging from the outer border of the 

 psoas muscle, crosses the iliacus muscle below the ilio-inguinal nerve, 

 and passing beneath Poupart's ligament, reaches the thigh beneath the 

 anterior superior iliac spine, where it divides into an anterior and a 

 posterior branch distributed to the integument of the outer side of 

 the hip and thigh. 



(rt) The poxtcrior hranch perforates the fascia lata and subdivides into two or 

 three others, which turn backwards and supply the skin upon the outer surface 

 of the limb, from the upper border of the hip-bone nearly to the middle of the 

 thigh. The highest among them are crossed by the cutaneous branches from the 

 last dorsal nerve. 



(h) An anterior hranch. the continuation of the nerve, is at first contained in a 

 sheath or canal formed in the substance of the fascia lata ; but, about four inches 

 below Poupart's ligament, it enters the subcutaneous fatty tissue, and is distri- 

 buted along the outer part of the front of the thigh, ending near the knee. The 

 principal offsets spring from its outer side. In some cases, this branch reaches 

 quite down to the knee, and communicates there with the internal saphenous 

 nerve. 



Obturator nerve. 



The obturator nerve is distributed to the adductor muscles of the 

 thigh, and to the hip and knee-joints. It arises from the lumbar 

 plexus by two roots, one from the third and the other from the fourth 

 lumbar nerve. Having emerged from the inner border of the psoas 

 muscle, opposite to the brim of the pelvis, it runs along the side of 

 the pelvic cavity, above the obturator vessels, as far as the opening 

 in the upper part of the thyroid foramen, through which it escapes 

 from the pelvis into the thigh. Here it immediately divides into an 



