THE LOWER LIMB 409 



in close association with the cnireus ; (2) the upper half of the inner 

 border of the patella ; and (3) very slightly into the inner border of 

 the tendon of the rectus femoris. 



Nerve-supply. — ^The posterior division of the anterior femoral 

 nerve by a branch called the nerve to the vastus intemus. This 

 ner\-e descends in close contact v.ith, and on the outer side of, the 

 long saphenous nerve, and with that nerve it traverses the upper 

 half of Hunter's canal. Jt furnishes a large offset to the knee-joint. 



The direction of the fibres of the muscle is downwards and for- 

 wards or outwards. 



WTulst the vastus extemus is easily separable from the crureus, 

 the vastus intemus and crureus appear at first sight to be one 

 muscle. A cellular interval, however, can be traced directly 

 upwards from the inner border of the patella to the inferior cervical 

 tubercle of the femur, along the course of which the two muscles can 

 be distinctly separated. When this separation has been eifected, 

 a characteristic elongated strip of the femur is laid bare upon the 

 inner side of the shaft, which is free from muscular fibres. 



Suprapatellar Tendon. — ^This is the common tendon in which the 

 four muscles constituting the quadriceps extensor cruris terminate. 

 The part of it which belongs to the rectus femoris is inserted into the 

 anterior part of the upper border of the patella, whence an expansion 

 of fibres descends over the front of that bone to blend with the fibres 

 of the ligamentum patellae. The tendon of the crureus is behind 

 that of the rectus femoris, where it has many of the fibres of the 

 vastus intemus associated with it, the rest of the last-named muscle 

 terminating partly upon the upper half of the inner border of the 

 patella, and partly upon the inner border of the tendon of the rectus 

 femoris. The vastus extemus is partly behind the rectus tendon, 

 and in part it joins the outer border of that tendon, and terminates 

 upon the upper third of the outer border of the patella. Beneath 

 the suprapatellar tendon there is a bursa, called the suprapatellar 

 bursa. It is continuous with the pouch which the synovial mem- 

 brane of the knee-joint sends upwards above the patellar surface 

 of the femur. 



Adion of the Vasti and Crureus, — ^These three muscles act as 

 powerful extensors of the knee-joint, the lowest fibres of the vastus 

 intemus at the same time d^a^^'ing the patella inwards. 



Subcrureus. — ^This muscle is in reahty the lowest and deepest 

 portion of the crureus. Viewing it as an independent muscle, it 

 arises in tvvo bundles from the front of the femur about 4 inches 

 above the patellar surface, and it is inserted into the suprapatellar 

 bursa, which is continuous with the upward prolongation of the 

 sjTiovial membrane of the knee-joint above the patellar surface of 

 the femiu". 



Nerve-supply. — The articular branch to the knee-joint which 

 comes from the innermost muscular branch to the crureus. 



Action. — The subcrureus is a tensor of the synoxnal membrane of 

 the knee-joint. 



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