202 THE MUSCLES. 



faces of the shaft and the great trochanter of the femur. The 

 base of the area is at the great trochanter, and its apex is at the 

 junction of the second and third fifths of the shaft on the hnea 

 aspera. The Hnea aspera forms the ventral boundary of the 

 triangle, Avhile its dorsal boundary is formed by a line drawn 

 from its apex to the dorsomedial angle of the great trochanter. 

 The mass unites with the rectus femoris {c) by its dorsal border 

 at the junction of the middle and distal thirds of the thigh. 



I Insertion into the oblique area on the outer surface of the 



patella near its lateral border in connection with the rectus 

 femoris. 



^ (3) M. vastus medialis (Fig. 92, c) lies on the medial side 



'^ij-ov^ of the thigh. 

 { 7 fit- Origin by fleshy fibres over a diamond-shaped area on the 



f' shaft of the femur lying between the medial branch of the linea 



i aspera and the area for the vastus lateralis. Proximad the 



area is bounded by the spiral line, and distad it is bounded by 

 a line parallel to the spiral line and having its proximal end at 

 about the junction of the first and second thirds of the bone. 

 The muscle forms a triangular, prismatic mass. It ends in a 

 thin aponeurosis which is continuous dorsad with the border of 

 the rectus femoris (Fig. 92, b), and ventrad sometimes with the 

 tendon of the gracilis (Fig. 91, b). 



Insertion into the medial border of the patella and the liga- 

 mentum patella,-. The insertion may extend onto the head of 

 the tibia. 



The adjacent surfaces of the vastus lateralis and the vastus 

 medialis are connected over their distal thirds by an aponeuro- 

 sis which passes transversely beneath the rectus femoris. The 

 distal end of the aponeurosis is inserted into the proximal 

 border of the patella. Its proximal end receives the insertion 

 of some muscle-fibres which form a part of the vastus medialis 

 as here described. This mass of fibres is described by Strauss- 

 Durckheim as the crural muscle. Sometimes the transverse 

 aponeurosis is continuous with only one of the two vasti and 

 sometimes with neither, so that the insertion of the crural of 

 Strauss-Durckheim becomes more or less independent. 



Relations of the vastus medialis. Outer (medial) surface 



