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 linea 
aspera. The linea aspera forms the ventral boundary of the 
triangle, while its dorsal boundary is formed by a line drawn 
frorn 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. 
lusertion 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 
of the thigh. 
Origin by fleshy fibres over a diamond-shaped area on the 
shaft of the femur lying between the medial branch of the linea 
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 ina 
thin aponeurosis which is continuous dorsad with the border of 
the rectus femoris (Fig. 92, 4), and ventrad sometimes with the 
tendon of the gracilis (Fig. 91, 4). 
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 
