112 



ANATOMY AND PHYSIOLOGY 



Practical point. Observe the number of muscles for external 

 rotation and note that the usual position of the foot is with the 

 toes turned outward. 



6, 



FIG. 91 MUSCLES OF THE 



THIGH. 



MUSCLES OF THE THIGH 

 Anterior 



On the front and the sides of the 

 femur are the muscles which extend the 

 leg four in number; they blend at their 

 insertion and therefore constitute a four- 

 headed muscle, the quadriceps femoris. 

 They are the rectus femoris, the vastus 

 lateralis, vastus medialis and the vastus 

 intermedius. 



Rectus femoris. Origin. The an- 

 terior inferior spine of the ilium and the 

 upper border of the acetabulum. The 

 three vasti. Origin. On the linea as- 

 pera and the three surfaces of the femur. 

 Insertion oj the four. By one tendon 

 passing in front of the knee-joint to the 

 tubercle of the tibia. (It encloses the 

 patella and has been improperly called 

 the ligamentum patellae.) 



Action. They extend the leg as in 

 walking, or with great force in kicking; 

 these muscles also keep the patella in 

 place during various positions of the 

 knee. 



Nerve. Femoral. 



The sartorius. The longest muscle 



i, 2, Iliacus and psoas; 3, 

 4, tensor fascia latae: 5, sar- in the body; it passes across the front 



! 6 la.S! T&i of the q uadri Ps- Origin.-The ante- 



medialis; 9, gracilis; 10, ad- rior superior spine of the ilium. Inser- 



ductor longus; ii, pectineus. ,. ,, . , , ,, ,.,. 



(Sappey.) tion. The inner surface of the tibia, 



just below the head. 



Action. Since it passes across to the medial side of the thigh, 

 and behind the medial epicondyle, it flexes the leg and at the 



