484 A MANUAL OF ANATOMY 



obturator externus anastomose in that muscle with the obturator 

 artery, which is a branch of the internal iliac. 



The perforating arteries are four in number — first, second, third, 

 and fourth. They pass backwards round the inner side of the 

 femur, and under the tendinous arches of the adductor magnus. The 

 first and second arteries pierce the adductor brevis and adductor 

 magnus, whilst the third and fourth pierce the adductor magnus 

 only. On reaching the back of the thigh, all four arteries give 

 off the following branches : muscular, to the hamstring muscles ; 

 branches to the great sciatic nerve ; and cutaneous, to the 

 integument of the outer and back parts of the thigh. The first 

 perforating also gives branches to the lower part of the gluteus 

 maximus, and the second (or third) furnishes the chief nutrient or 

 medullary artery of the femur. The perforating arteries, now much 

 reduced in size, wind round the back and outer side of the femur. 

 In this course the first pierces the femoral insertion of the gluteus 

 maximus, and the second, third, and fourth pierce the femoral head 

 of the biceps and the external intermuscular septum. The first and 

 second terminate in the vastus externus, and the third and fourth 

 in the crureus, all four anastomosing with branches of the external 

 circumflex, the fourth also taking part in the deep geniculate arterial 

 rete. At the back of the thigh the perforating arteries anastomose 

 freely with one another. The first perforating also anastomoses 

 with the gluteal, sciatic, and ascending branch of the internal 

 circumflex in the digital fossa, thus forming the digital anastomosis, 

 and with the sciatic and transverse branches of the internal and 

 external circumflex between the adductor magnus and quadratus 

 femoris to form the crucial anastomosis. The lower two perforating 

 arteries anastomose at the back of the thigh with the superior 

 muscular branches of the popliteal. The branches of the per- 

 forating arteries to the great sciatic nerve anastomose with the 

 comes nervi ischiadici branch of the sciatic. 



The muscular branches of the superficial femoral artery arise 

 partly in Scarpa's triangle and partly in Hunter's canal. The 

 lowest of these branches, which is somewhat large and very 

 constant, is given off at the lower end of Hunter's canal. It 

 passes outwards behind the femur, piercing the external inter- 

 muscular septum and the femoral head of the biceps, and it termi- 

 nates in the crureus, in which it anastomoses with the long 

 descending branch of the external circumflex, the fourth perforating, 

 and the superior external articular of the popliteal. 



The saphenous branches are two or three in number, and arise 

 from the superficial femoral in Scarpa's triangle. They supply 

 the superficial femoral or saphenous glands and the structures 

 around the terminal part of the long saphenous vein. 



The arteria anastomotica magna arises from the superficial 

 femoral at the lower end of Hunter's canal, and at once divides 

 into a superficial and deep branch. In many cases these branches 

 arise independently from the main vessel. The superficial bransh 



