DISSECTION OF THE POSTERIOR LIMB. 61 



passed through the obturator externus muscle. Other branches of the 

 same nerve will be found supplying the small adductor and the pecti- 

 neus. 



The Femoral Artery (Plate 14). The i-emaining portion of this 

 vessel is now exposed as it winds round behind the shaft of the 

 femur, leaving its impress on the bone. It is seen passing in between 

 the heads of the gastrocnemius muscle, at which point it takes the 

 name of jyopliteal. In this part of its coui'se it gives off only one vessel 

 of note — the femoro-popliteal. 



The Femoro-popliteal Artery. The point of origin of this branch 

 marks the lower limit of the femoral artery. It passes backwards in a 

 horizontal direction, and penetrates the semitendinosus. Near its origin 

 it gives off a considerable branch which ascends behind the femur, sup- 

 plying the biceps, and anastomosing with the profunda. Other branches 

 descend from it to the gastrocnemius. 



PoPLiTiiAL Lymphatic Glands. A few glands will be found on the 

 track of the femoro-popliteal artery between the semitendinosus and 

 biceps femoris muscles. 



The Profunda or Deep Femoral Artery. In the preceding- 

 stage of the dissection this branch of the femoral was seen at its 

 origin. It passes downwards and backwards, between the adjacent 

 edges of the iliacus and obturator externus, and under cover of the 

 pectineus and adductor parvus. Above the insertion of the quadratus 

 femoris it crosses behind the femur, where its terminal branches descend 

 to supply the biceps. It also furnishes collateral branches to the 

 pectineus, gracilis, and adductors. 



Veins. The foregoing arteries are accompanied by satellite veins of 

 the same names. 



The Quadratus Femoris (Plates 14 and 16). This is a somewhat slender 

 riband-shaped muscle. It arises from the lower surface of the ischium 

 in fi-ont of the tuberosity, and it becomes inserted into an oblique line 

 on the back of the femur, at the level of the third trochanter. 



Action. — It is an extensor and outward-rotator at the hip. 



The Obturator Externus (Plate 14). This muscle, which is coarsely 

 fasciculated, covers the obturator foramen, and conceals the obturatoi- 

 nerves and vessels as they emerge from the pelvis. It is traversed by 

 two branches of the obturator nei've, the posterior of which is for the 

 great adductor, while the anterior splits into branches for the supply 

 of the small adductor, pectineus, and gracilis. It • arises from the lower 

 surface of the pubis and ischium, and is inserted into the trochanteric 



Action. — It is an extensor and outward-rotator at the hip. 

 Directions. — The nerves which emerge from the obturator externus 

 should be traced through the substance of that muscle to their oriaiu 



