2iO MUSCLES OF THE LOWER LIMB. 



inserted into the posterior surface of the tendon belonging to the 

 superficial fibres. On either side of the origin of this part of the 

 muscle there is a longitudinal band of the lateral surface of the femur 

 from which no muscular fibres arise : this band varies somewhat in 

 breadth in difi'erent subjects, and it is also broader on the inner aspect 

 of the shaft than on the outer. 



liclatlon.s. — On its anterior svu-face this muscular mass is in contact with the 

 rectus femoris and sartorius muscles and the anterior crural nerve. At its inner 

 border run the femoral artery and vein, and the muscle is in contact with the 

 iliacus, adductor long-us. and adductor magnus, being firmly united to the last 

 two by the aponeurotic fibres which form Hunter's canal. On its outer surface 

 lies the vastus externus. 



The siibcrursiis is a small band of muscular fibres, which extends 

 from the lower part of the anterior surface of the femur to the upper 

 part of the synovial membrane of the knee-joint, on which it ends in 

 scattered fibres. 



Bclathms. — This little muscle is placed beneath the crureus muscle, and in 

 some cases it is united with that muscular mass. It is not unfrequently double, 

 or consists of two separate bundles. 



Varieties.— Hhe parts of the quadriceps muscle are not liable to many anoma- 

 lies. The rectus lias been found with an additional origin from the anterior 

 superior spine of the ilium ; or, again, its acetabular origm may be wanting. 

 The vasti muscles are sometimes bUaminar, as is seen also normally in many 

 birds. 



Nerves. — The psoas muscle is supplied by small branches from the lumbar 

 plexus. The iliacus. quadriceps extensor cruris and sartorius are supplied by the 

 anterior crural nerve, and the tensor vaginas femoris by the superior gluteal 

 nerve. 



Actions. — The iUo-psoas muscle, the flexor of the hip-joint, bends the thigh on 

 the body, or the body on the thigh, according as either of these is the more 

 fixed. It also produces considerable rotation outwards. 



The tensor vntj'nia; femoris assists the action of the other muscles by making 

 tense tlie fascia lata. It aids the gluteus medius and minimus in rotating the 

 limb inwards, but its action in this respect is exactly opposed by tlie upper fibres 

 of the gluteus maximus, along with which it acts as an abductor of the limb, 

 and is considered by Meyer (op. cit. p. 222) to be an extensor of the knee. 



The sartorius produces the flexion of the hip and knee-joints, accompanied by 

 abduction. It has been supposed to be the muscle principally concerned in pro- 

 ducing the posture assumed by the tailor in sitting, and hence its name ; but 

 Duchenne denies that this is its special action. 



The quadrlet-ps crtmsor femoris extends the knee-joint ; but its action is not 

 requisite for the maintenance of tlie erect attitude, the knee-joint remaining in 

 complete extension witliout muscular aid while the foot is firmly planted on the 

 ground. This may be tested by the fact that the patella of a person standing with 

 the knee extended will be found to lie quite loosely, but will become at once 

 fixed when it is attempted to lift the foot. 



The reettis femoris flexes the hip and extends the knee : it acts mainly from its 

 anterior head of origin when tlie thigh is fully extended, and the posterior head 

 is alone tense when the thigh is bent. 



INTERNAL FEMOKAL OR ADDUCTOR MUSCLES. 



The gracilis or adductor gracilis muscle, long and slender, arises 

 by a thin tendon from the inner margin of the pubic bone, along 

 the lower half of the symphysis and the upper part of the pubic arch. 

 The lower tendon, which is at first round, is inserted by u flattened and 



