VASTI AND CRUREUS. 229 



of the hip-joint, the external circumflex vessels, crureus, and vastus 

 internus and externus. 



The rectus must now be divided through its middle, and the two 

 ends turned aside, to bring clearly into view the next muscles. 



The three next muscles are generally considered collectively under 

 the name of triceps extensor cruris. Adopting this view, the muscle 

 surrounds the whole of the femur, excepting the rough line (linea 

 aspera) upon its posterior aspect. Its division into three parts is not 

 well defined ; the fleshy mass upon each side being distinguished by 

 the names of vastus internus and externus, the middle portion by 

 that of crureus. 



The Vastus externus, narrow below and broad above, arises from 

 the outer border of the patella, and is inserted into the femur and 

 outer side of the linea aspera, as high as the base of the trochanter 

 major. 



Relations. By its superficial surface with the fascia lata, rectus, 

 biceps, semi-membranosus and gluteus maximus, a synovial bursa 

 being interposed. By its deep surface with the crureus and femur. 



The Vastus internus, broad below and narrow above, arises from 

 the inner border of the patella, and is inserted into the femur and 

 inner side of the linea aspera as high up as the anterior inter-trochan- 

 teric line. 



Relations. By its superficial surface with the psoas and iliacus, 

 rectus, sartorius, femoral artery and vein and saphenous nerves, 

 pectineus, adductor longus, brevis, and magnus, and fascia lata. By 

 its deep surface with the crureus and femur. 



The Crureus (crus, the leg) arises from the upper border of the 

 patella, and is inserted into the front aspect of the femur, as high as 

 the anterior inter-trochanteric line. When the crureus is divided 

 from its insertion, a small muscular fasciculus is often seen upon the 

 lower part of the femur, which is inserted into the pouch of synovial 

 membrane, that extends upwards from the knee-joint, behind the 

 patella. This is named, from its situation, sub-crureus, and would 

 seem to be intended to support the synovial membrane. 



Relations. By its superficial surface with the external circumflex 

 vessels, the rectus, and vastus internus and externus. By its deep 

 surface with the femur, the sub-crureus, and synovial membrane of 

 the knee-joint. 



Actions. The tensor vaginse femoris renders the fascia lata tense, 

 and slightly inverts the limb. The sartorius flexes the leg upon the 

 thigh, and, continuing to act, the thigh upon the pelvis, at the same 

 time carrying the leg across that of the opposite side, into the posi- 

 tion in which tailors sit ; hence its name. Taking its fixed point 

 from below, it assists the extensor muscles in steadying the leg, for 

 the support of the trunk. The other four muscles have been collec- 

 tively named quadriceps extensor, from the similarity of action. 

 They extend the leg upon the thigh, and obtain a great increase of 

 power by their attachment to the patella, which acts as a fulcrum. 



