282 



THE CAT. 



[CHAP. rx. 



a small trunk, which unites with the large lumbo-sacral cord, and 

 forms the great sciatic nerve, the lesser sciatic nerve "being given off 

 close to the junction of the " small trunk " just mentioned, with the 

 lumbo-sacral cord (ss). 



The sacral plexus lies on the ventral surface of the pyriformis 

 muscle. 



The ilio-hypogastric nerve comes forth from the anterior part 

 of the psoas, pierces the trans versalis, and divides branches coming 

 to the surface in the skin of the hinder part of the abdomen. The 

 ilio-ingidnal nerve follows a very similar course to the last, but is 

 distributed to the skin of the groin and external generative organs. 



The gemto-crural nerve, which is a very long one, passes back 

 beneath Poupart's ligament, one part goes to the skin of the thigh 

 and the other part to the spermatic cord in the male, and to the 

 vicinity of the vaginal orifice in the female. The external cutaneous 

 nerve also passes back beneath Poupart's ligament and goes to the 

 skin outside the hip and thigh. 



The obturator nerve, which is of large size, passes along the 

 side of the pelvis, with the obturator vessels, and perforates the 

 obturator membrane, being distributed to the external obturator 

 muscle, the pectineus gracilis, and the adductor. The ANTERIOR 

 CRURAL nerve is the great nerve of the front of the thigh, and is the 

 largest of those which quit the lumbar plexus. Coming out from 

 the psoas it passes down and divides, giving off nerves to the skin of 

 the front and inside of the thigh, to the skin of the inner side of the 

 leg and foot, and also branches to the sartorius, pectineus, and 

 quadriceps extensor muscles. The superior gluteal nerve passes 

 out in front of the pyriformis, and is distributed to the glutei 

 muscles. 



The GREAT SCIATIC nerve, which is the largest nerve in the 

 body, passes out through the sacro-sciatic notch behind the pyri- 

 formis muscle, and proceeds between the great trochanter and the 

 tuberosity of the ischium, beneath the gluteus maximus, and (with 

 the sciatic artery) resting upon the obturator internus and quadratus 

 femoris muscles. It descends beside the adductor magnus to the 

 popliteal space, bifurcating into two branches, called respectively 

 the internal and external popliteal nerves. The first of these (which 

 is the larger) continues down behind the popliteus muscle, and then 

 takes the name of posterior tibia I nerve, descending near the pos- 

 terior tibial artery to the inner malleoluSj and dividing into the 

 internal and external plantar nerves. The former of these accom- 

 panies the internal plantar arteiy, and is distributed to the three 

 inner (or tibial) toes, and to the inner side of the fourth. The 

 external plantar nerve goes to the fifth toe and outer side of the 

 fourth, after crossing obliquely beneath the sole with the external 

 plantar artery. The posterior tibial nerve supplies all the flexor 

 muscles of the foot and toes, and the skin of the sole of the foot 

 and part of the back of the leg. The second division of the 

 popliteal nerve, i.e., the external popliteal, or pcroncal nerve, curves 



