156 



DISSECTION OF THE THIGH. 



Cut the 

 rectus, 

 and display 

 three deep 

 heads of 

 extensor : 



define 

 vastus 

 externus ; 



separate 

 crureus and 

 vastus 

 internus, 



beginning 

 below, 



and expos- 

 ing bare 

 surface of 

 bone. 



Vastus 

 externus 

 is thin at 

 the origin ; 



ends in 

 common 

 tendon ; 



parts in 

 contact 

 with the 

 surfaces. 



Vastus 

 internus 

 arises from 

 femur and 

 adductor 

 tendons ; 



femoris, iliacus, and sartorius ; but in the rest of its extent it is 

 superficial. It conceals branches of the external circumflex artery 

 and anterior crural nerve, and rests on the crureus and vasti. The 

 upper tendon of the rectus reaches farthest on the anterior surface ; 

 while the lower tendon is most extensive on the posterior aspect of 

 the muscle. 



Dissection. To see the remaining muscles, cut across the rectua- 

 near the lower end and raise it without injuring the branches of 

 vessels and nerves beneath (fig. 59). The muscular mass covering 

 the shaft of the femur is to be thoroughly cleaned, and its three 

 parts denned in the following way : 



The division between the vastus externus on the outer side and 

 the crureus in front is readily made in the situation of some vessels 

 and nerves, which descend along the anterior border of the vastus 

 externus. 



To separate the vastus internus from the crureus, the lower end 

 of the rectus must be turned down as far as possible, when a cleft 

 will be evident in the subjacent tendon above the inner part of the 

 patella. From this interval the division may be easily carried 

 upwards between the two muscles, but at the upper end some fleshy 

 fibres generally need cutting to complete the separation. If the 

 vastus internus be turned inwards off the crureus, a large part of 

 the inner surface of the femur will be seen to be free from 

 muscular attachment. 



The VASTUS EXTERNUS has a narrow attachment to the femur in 

 comparison with its size (fig. 60, and fig. 61, p. 158). It takes origin 

 from the upper half of the femur, by a piece from half an inch to 

 an inch thick, which is attached to the root of the neck of the femur, 

 and the fore and outer parts of the root of the great trochanter ; 

 then along the outer side of the gluteal ridge, and the upper half 

 of the linea aspera ; and lastly from the contiguous external inter- 

 muscular septum. Inferiorly most of the fibres of the muscle end 

 in a flat tendon, which blends with those of the other portions in 

 the common tendon, but the lowest fibres of all are inserted directly 

 into the outer border of the patella. 



The vastus externus is the largest part of the quadriceps, and 

 produces the prominence on the outer side of the thigh. Its 

 cutaneous surface is aponeurotic above, and is partly covered by 

 the rectus, tensor vaginae femoris, and glutens maximus muscles. 

 The deep surface rests on the crureus, and receives branches of the 

 external circumflex artery and anterior crural nerve. 



The VASTUS INTERNUS (figs. 58, E, p. 151) also has a narrow 

 origin from the lower part of the anterior intertrochanteric line 

 and from the inner surface of the femur (figs. 60 and 61) along the 

 linea aspera, from the upper part of the internal supra-condylar 

 ridge, and, in the lower half of the thigh, from the front of the 

 tendons of the adductor longus and magnus. The fibres join an 

 aponeurosis which blends in the common tendon, and is also 

 attached directly to the inner margin of the patella reaching lower 

 than the vastus externus. 



