ANATOMY IN A NUTSHELL. 137 



Crureus, form one muscle — the Quadriceps extensor, which is the great extensor 

 of the leg. This might be called one muscle with four heads and one insertion. 

 The Rectus is situated in the middle and anterior part of the group and has two 

 heads. These heads join at an acute angle. Its superficial fibers are bipenni- 

 form. and its deep ones run straight down to the deep aponeurosis. The broad 

 and thick aponeurosis which occupies the lower two-thirds of the posterior sur- 

 face of the muscle gradually ends in a flattened tendon. 



LESSON XXXVI. 



Origin. — (Plate XLIII.) — The anterior or straight tendon, from the an- 

 terior inferior spinous process of ilium; the posterior, or reflected tendon, from 

 a groove above the brim of the acetabulum. 



Insertion. — (Plate LXXIV.) — Into the patella in common with the Vasti 

 and Crureus. 



Action. — Assists Psoas muscle to bend pelvis and trunk forward and sup- 

 port them upon the femur. 



Nerve Supply. — Anterior crural. 



Blood Supply. — Femoral artery. 



Vastus externus. — Description. — (Plates LXIV-LXVIII-LXXIV.) — This 

 muscle is the largest part of the Quadriceps extensor. The strong aponeurosis 

 on the under surface at the lower part of this muscle receives the fillers which 

 form a large fleshy mass. The tendon of this muscle gives an expansion to the 

 capsule of the knee-joint. 



Origin. — (Plate XLVIII.) — By a broad aponeurosis attached to ihe upper 

 half of anterior intertrochanteric line, to the anterior and inferior borders of the 

 root of the great trochanter, to the outer lip of the gluteal ridge, and to the 

 upper half of the outer lip of the linea aspera. This aponeurosis covers the 

 upper three-fourths of the muscle and from its inner surface many fibers take 

 origin. A few additional fibers arise from the tendon of the Gluteus maximus, 

 and from the external intermuscular septum between the Vastus externus and 

 short head of Biceps. 



Insertion. — (Plate LXXIV.) — Into patella. 



Action. — Extends knee. 



Nerve Supply. — Anterior crural. 



Blood Supply. — External circumflex. 



Vastus interims.— Description. — (Plates LXIV-LXVIII-LXXIV.) —If 

 the Rectus is reflected a narrow space is seen between the Vastus interim- and 

 the Crureus extending upward from the inner border of the patella. At this 

 space they can lie separated, bin they arc in reality one muscle. The aponeuro- 

 sis which lies on the deep surface of the muscle receives fibers from the muscle, 

 which are directed downward and forward. 



Origin. — (Plate XLVIII.) — Lower one-half of anterior intertrochanteric 

 line,, the spiral line, the inner lip of the linea aspera, the upper pari of the in- 

 ternal supracondylar line, and the tendon of the Adductor magnus and internal 

 intermuscular septum. 



