254 THE MUSCLES OF THE LOWER LIMB. 



direction of a line from the inner part of the patella to the lower end of the anterior 

 intertrochanteric line of the femur, and the two portions can thus be separated, 

 although their fleshy fibres are usually continuous above. The vastus internus, like 

 the vastus externus, has a narrow origin from the femur, by a superficial aponeurosis 

 and deeper fleshy fibres, along the spiral line and the inner lip of the linea aspera, 

 while in the lower half numerous fibres arise from the tendons of the adductor longus 

 and adductor magmis. The muscular fibres are directed downwards and forwards, 

 and end mostly on a deep aponeurosis which forms below the innermost part of the 

 common tendon ; the lower fibres, however, which pass inwards more obliquely than 

 the upper ones, end by being inserted, shortly tendinous, into the inner margin of 

 the patella for its upper half. A few superficial fibres also join the adjacent margin 

 of the rectus tendon, and from its lower border an expansion is given off to the cap- 

 sule of the knee. 



The crureus has a fleshy origin from the anterior surface of the femur for its 

 upper two-thirds, from the outer surface of the bone in front of and below the 

 attachment of the vastus externus, and from the lower half of the external intermus- 

 cular septum. The fibres are directed downwards, those of the outer and lower part 

 also considerably forwards, and they end on a superficial aponeurotic lamina which 

 forms the deepest portion of the common tendon. The crureus consists of four or 

 five superposed fleshy layers, the origins of which form a series of transverse arches 

 with intervening bare spaces on the front of the femur ; and between this portion of 

 the muscle and the vastus internus the greater part of the internal surface of the 

 bone is also free from muscular attachment. 



The common or suprapatellar tendon, in which the four portions of the quadriceps 

 muscle terminate below, is broad and flat, and is inserted into the fore part of the 

 upper border of the patella, a few fibres being prolonged over the anterior surface of 

 the bone into the superficial portion of the infrapatellar tendon or ligamentum 

 patella; (p. 184). 



Sulcrureus. This name is given to one or two thin bands of muscular fibres 

 which might be regarded as the deepest layer of the crureus. It arises from the 

 lower part of the anterior surface of the femur, and is inserted below by scattered 

 fibres into the upper part of the sy no vial membrane of the knee-joint. 



Relations. The rectus is covered at its upper end by the tensor vaginas f emoris. iliacus 

 and sartorius muscles, and the acetabular tendon lies beneath the gluteus minimus. In the 

 rest of its extent it is covered only by fascia. It rests upon the capsular ligament of the hip- 

 joint and the deep portions of the quadriceps : behind it pass also the external circumflex 

 artery and branches of the anterior crural nerve. The vastus externus forms the large mass 

 on the outer side of the thigh. It is covered by the fascia lata and the aponeurotic insertions 

 of the gluteus maximus and tensor vaginae f emoris ; and its anterior border is concealed by 

 the rectus. It rests upon the crureus, and the branches of the external circumflex artery and 

 anterior crural nerve entering it close to its anterior border pass between the two. The vastus 

 internus is partly covered by the sartorius and rectus ; between these muscles it is superficial, 

 giving rise to the prominence at the lower part of the inner side of the thigh. In the middle 

 two-fourths of the thigh it forms the outer wall of the space called Hunter's canal, which 

 lodges the femoral vessels. The crureus is almost completely covered by the rectus and vasti, 

 only a small portion being superficial on the outer side, behind the free posterior border of the 

 vastus externus. Beneath the suprapatellar tendon is a bursa which communicates in most 

 cases freely with the cavity of the knee-joint. 



Varieties. The parts of the quadriceps muscle are not liable to many anomalies. The 

 rectus has been found with an additional origin from the anterior superior spine of the ilium, 

 or wanting its acetabular origin. The vasti muscles are sometimes bilaminar, a condition 

 which is normal in many birds. 



Nerves. The sartorius and quadriceps extensor cruris are supplied by the anterior crural 

 nerve (2, 3, 4 1). 



Actions. The sartorius muscle produces flexion of the hip and knee-joints, accompanied 

 by aversion of the thigh : it also assists in rotating inwards the leg. It has been supposed to 



