THE THIGH 201 



Intermuscular Septa. Divide the tractus ilio-tibialis of the 

 fascia lata distal to the point at which it splits to enclose the 

 tensor fasciae latae. This is done so as to obtain a better view 

 of the vastus lateralis, and in order to demonstrate satisfactorily 

 the lateral intermuscular septum. Take hold of the distal 

 portion of the tractus ilio-tibialis and draw it forcibly laterally ; 

 at the same time push medially the vastus lateralis muscle, 

 and a strong fibrous septum will be seen passing medially 

 from the fascia lata towards the linea aspera. This is the 

 lateral intermuscular septum of the thigh, a partition interposed 

 between the vastus lateralis and the short head of the biceps 

 femoris. Follow it proximally and distally with the finger. 

 The fibres of the vastus lateralis are seen arising from it, but 

 little difficulty will be experienced in making out its attach- 

 ment to the linea aspera and lateral supracondylar ridge of the 

 femur. It extends in a proximal direction as far as the 

 insertion of the glutaeus maximus, whilst distally it reaches 

 the lateral condyle of the femur. Immediately proximal 

 to the lateral condyle of the femur it is pierced by the 

 lateral superior genicular artery and nerve. The medial inter- 

 muscular septum is interposed between the adductors and the 

 vastus median's, and should also be examined. It is thin 

 in comparison with the lateral septum. 



M. Quadriceps Femoris. This muscle is composed of 

 four portions. The rectus femoris, which is placed in the 

 anterior part of the thigh, and is quite distinct from the others, 

 except at its insertion ; the vastus lateralis, vastus inter- 

 medius, and the vastus medialis, which clothe the body of the 

 femur on its lateral, anterior, and medial aspects, and are 

 more or less blended with each other. 



M. Rectus Femoris. This muscle arises by two tendinous 

 heads of origin, which may be exposed by dissecting deeply in 

 the interval between the iliacus and tensor fasciae latae. The 

 anterior or straight head springs from the anterior inferior spine 

 of the ilium (Fig. 74, p. 200); the posterior or reflected head 

 arises, under cover of the glutaeus minimus, from a marked 

 impression on the lateral surface of the ilium, immediately 

 above the upper part of the rim of the acetabulum (Fig. 74, 

 p. 200). It is connected both with the capsule of the hip- 

 joint and the deep lamina of the ilio-tibial tract of the fascia 

 lata. 



At the present stage of dissection it is only possible to display the 



