THE FEMUR 



181 



and when very prominent is termed the third trochanter. The medial hp curves 

 medialward below the lesser trochanter, where it becomes continuous with the 

 intertrochanteric line; the intervening portion bifurcates and is continued upward 

 as two lines, one of which ends at the small trochanter, and receives some 

 fibres of the iliacus, whilst the other is the linea pectinea and marks the insertion 

 of the pectineus muscle. 



Toward the lower third of the shaft the medial and lateral lips of the linea 

 aspera again diverge, and are prolonged to the condyles bj' the medial and lateral 

 supra-condylar lines, enclosing between them a triangular surface of bone, the 

 popliteal surface [planum popliteum] of the femur, which forms the upper part of 

 the floor of the popliteal space. The lateral line is the more prominent and ter- 

 minates below in the lateral epicondjde. The mechal one is interrupted above, 

 where the femoral vessels are in relation with the bone, better marked below, 

 where it terminates in the adductor tubercle, a small sharp projection at the sum- 

 mit of the medial epicondyle, which affords attachment to the tendon of the ad- 

 ductor magnus. 



Fig. 217. — A Diagram to show the Pressure and Tension Curves of the Femur. 



(After Wagstaffe.) 



Near the centre of the linea aspera is the foramen for the medullary artery, directed upward 

 toward the head of the bone. 



From the medial lip of the linea aspera and the lower part of the intertrochanteric line 

 arises the vastus medialis (internus), and from the lateral lip and the side of the gluteal ridge 

 arises the vastus lateralis (externus). The adductor magnus is inserted into the medial lip of 

 the linea aspera, from the medial side of the gluteal tuberosity above, and the medial supra- 

 condylar line below. Between the adductor magnus and vastus medialis (internus) four muscles 

 are attached: the pectineus and iliacus above, then the adductor brevis, and lowest of all, the 

 adductor longus. Above, in the interval between the adductor ?nag7ius and the vastus lateralis 

 (externus), the gluteus maximus is inserted; in the interval lower down is the short head of 

 the biceps, taking origin from the lower two-thirds of the lateral] lip of the linea aspera and the 

 upper two-thirds of the lateral supra-condj'lar line. On the popliteal surface of the bone, just 

 above the condyles, are two rough areas from which fibres of the two heads of the gastrocnemius 

 take origin. Above the area for the lateral head of the gastrocnemius is a slight roughness for 

 the plantaris. 



For purposes of description it is convenient to regard the shaft of the femur as 

 presenting anterior, medial, and lateral surfaces, although definite borders separat- 

 ing the surfaces from one another do not exist. All three surfaces are smooth 

 and the anterior is not separated from the lateral by ridges of any kind. In the 

 middle third of the shaft the medial and lateral surfaces approach one another 

 behind, being separated by the linea aspera. 



