304: NOTES ON THE ANATOMY OF BIKDS, 



penultimate lunibars the long saphenous and obturator nerves take 

 origin. This cord is then joined by the last lumbar to form the 

 femoral or anterior crural nerve. 



The obturator nerve, after giving off a branch to the obturator 

 internus muscle, passes through the foramen ovale, and finally 

 ends in the substance of the adductor magnus. 



The femoral nerve gives off branches to the glutei, the sartorius, 

 the vastus externus, the rectus femoris*, the pectineus (ambiens), 

 and adductor magnus, in addition to cutaneous branches to the 

 inner side of the thigh and leg. 



The sacral plexus is formed by the sacral nerves with a branch 

 (lumbosacral tordj for the last lumbar. The lumbo-sacral cord 

 and the first three sacral nerves join to form a stout anterior cord 

 from which the nerve to the quadratus femoris * (and gemellus?) 

 is derived. The two last sacral nerves join and give off a 

 tolerably large branch before joining the anterior cord. The 

 main trunk formed by the junction of the anterior and posterior 

 cords of the plexus, sooner or later divides into two distinct 

 fasciculi — the sciatic nerves — which run down the back of the thigh 

 close together. 



The branch given off by the posterior cord of the plexus courses 

 over the obturator externus muscle, and then passes between the 

 biceps, adductores longus and brevis above, and the adductor 

 magnus below, at which point it breaks up into branches of 

 supply for the seniitendi.nosus, semimembranosus, adductor brevis 

 and adductor longus, in addition to some cutaneous branches, 

 and a slender nerve which runs backwards to the tail, usually 

 joining one of the caudal nerves. 



*The muscle here named quadratus femoris has been sometimes regarded as 

 the equivalent of the obturator externus ; its nerve supply, taken in 

 connection with its ischial origin, would seem to indicate that the former 

 view of its homology is the correct one, 



