104 TOPOGEAPHICAL ANATOMY OF 



(5) A. nufritia femoris. — The nutrient artery of the femur leaves 

 the femoral as this vessel pierces the adductor muscle. 



(6) A. femoris posterior. — At the present stage of the dissection 

 the posterior femoral artery is hidden by the semimembranosus muscle. 

 It will be exposed shortly. 



N. FEMOEALis. — The femoral nerve arises from the lumbar plexus. 

 Its termination alone is demonstrable at present, and will be found 

 between the deep face of the sartorius and the ilio-psoas. It accom- 

 panies the anterior femoral artery as this vessel sinks between the 

 medial vastus and the rectus femoris muscles, and is the nerve of 

 supply to the quadriceps mass of muscles. 



The origin of the saphenous nerve, one of the branches of the 

 femoral, will be found underneath the sartorius muscle, and the nerve 

 can be followed along the anterior border of the femoral artery. The 

 superficial part of its course has already been examined, so far as it 

 lies in the thigh. 



Dissection. — The pectineus, adductor, and semimembranosus muscles 

 must now be cut across about their middle and the cut ends turned 

 aside. In reflecting the pectineus and adductor, the dissector must 

 note the branches of the obturator nerve that supply them. He must 

 also look for branches from the sciatic nerve to the semimembranosus 

 muscle. 



If the subject has been well preserved, it is possible that the 

 adductor and semimembranosus muscles may be too stiff to permit the 

 dissection to be conducted with ease. In this case the middle part of 

 each muscle should be cut away entirely. 



The distal part of the femoral artery is now exposed as it lies 

 between the femur on the one hand and the adductor and semimem- 

 branosus muscles on the other. 



On the deep face of the biceps muscle the tibial and common 

 peroneal nerves will be observed ; but their full consideration is better 

 postponed until an examination of the thigh is made from the lateral 

 aspect, when their origin from the sciatic nerve can be determined. 



The other structures now exposed are branches of the obturator 

 nerve and vessels, the deep femoral artery and its companion vein, 

 the insertion of the ilio-psoas muscle, and the external obturator and 

 quadratus femoris muscles. 



M. QUADRATUS FEMOEis. — The quadrate ^ muscle is slender and 

 narrow, and has the outline of an elongated triangle. From its origin 

 near the centre of the ventral surface of the body of the ischium the 

 muscle passes obliquely to its insertion into the proximal third of the 

 posterior surface of the femur near the lesser trochanter. 



M. OBTURATOR EXTERNUS.— The triangular or fan-shaped external 

 obturator ^ muscle arises from the ventral surface of the ischium and 

 pubis in the neighbourhood of the obturator foramen. The converging, 



1 Quadratus [L.J, squared or square ; from the outline of the human muscle. 



2 OUuro [L.], to stop up, to close. 



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