236 A MANUAL OF ANATOMY 



as-pera, which has two lips, outer and inner, and a narrow inter- 

 vening space. The outer lip gives attachment, from behind forwards, 

 to the short head of the biceps, external intermuscular septum, 

 vastus externus over its upper half, and crureus over its lower 

 half. The inner lip gives attachment, from behind forwards, 

 to the adductor magnus, adductor longus, internal intermuscular 

 septum, and vastus internus. A little above the centre of the shaft, 

 close to the inner lip, is the medullary foramen for a branch of the 

 second, or third, perforating artery, the direction of the foramen 

 and the canal to which it leads being upwards towards the head. 



Over the upper third of the shaft the lips of the linea aspera diverge. 

 The outer lip is prolonged to the base of the great trochanter pos- 

 teriorly, and over about its lower 3 inches it is conspicuously rough, 

 this portion being known as the gluteal ridge, which gives insertion 

 to the lower part of the gluteus maximus. Close to the outer side 

 of this ridge the vastus externus takes origin, and close to its inner 

 side the upper fibres of the adductor magnus take insertion. The 

 inner lip bifurcates. One division is prolonged in a winding manner 

 round the inner aspect of the shaft, passing in front of the small 

 trochanter and terminating at the inferior cervical tubercle, where 

 it passes into the anterior intertrochanteric line. This winding 

 division is called the spiral line, and it gives origin to the upper 

 fibres of the vastus internus. The other division is prolonged to the 

 back of the small trochanter, and it gives insertion over its upper 

 third to the pectineus, and over its whole extent to the adductor 

 brevis, the latter being behind the former. The relation of muscles 

 at the back of the upper end of the shaft, from the small trochanter 

 outwards to the outer margin of the gluteal ridge, is as follows : 

 ilio-psoas; pectineus; adductor brevis; lower fibres of quadratus 

 femoris ; adductor magnus ; gluteus maximus ; and vastus externus. 

 The narrow intervening space of the linea aspera between its two 

 lips is in line with the linea quadrati above. 



Over the lower third of the shaft the lips of the linea aspera 

 diverge widely, and are prolonged to the condyles as the external and 

 internal supracondylar ridges. These enclose between them a flat 

 triangular area, called the popliteal surface, which is also known as 

 the trigonum femoris. Over this region the periosteum is very thin, 

 and this part of the bone is predisposed to necrotic changes. The 

 popliteal surface forms the upper part of the floor of the popliteal 

 space. The external supracondylar ridge gives attachment over its 

 whole extent to the external intermuscular septum, and over about 

 its upper two-thirds to the short head of the biceps and the crureus. 

 For a short distance below, it gives origin to the plantaris, and 

 immediately external to this, to fibres of the outer head of the gastroc- 

 nemius. The internal supracondylar ridge is interrupted about an 

 inch below its commencement by a slight groove, which is produced 

 by the femoral vessels, and at its lower extremity, close to the internal 

 condyle, there is a projection called the adductor tuberch, for the 



