The Lower Extremity and Pelvis 147 



a prominent crest, as is normally found in the femora of speedy animals such as the 

 horse and deer. When such a centre develops in man it appears about the age of 

 twenty-one and joins in a few years. 



The gluteal ridge marks the direct tendon of Gluteus maximus, but an expansion 

 downwards from this tendon forms the external intermuscular septum (Fig. 120), 

 so that the line of this septum on the bone is a direct continuation of the ridge and 

 passes between the short head of Biceps internally and origin of Vastus externus on 

 the outer side. 



The linea aspera can be more or less analysed into its constituent lines by compa- 

 rison of various bones with each other. The irregularly- fused ridges that compose it 

 are purely secondary lines situated on a primary border of the shaft, so that when a 

 young bone is examined there is no appearance of these rough ridges, but only the 

 rounded border of the bone, into which the aponeuroses are inserted. Later the 

 attached aponeurotic structures have a certain amount of ossification extending 

 into them from the periosteum, and at the same time a small artery that runs at first 

 between the aponeuroses is by this means taken into the new-formed ridges and makes 

 the vascular canal found in this region. 



Analysis of the linea aspera places its attachments as follows (Fig. 120) : External 

 intermuscular septum from gluteal ridge to a small ill-defined tubercle on the external 

 supracondylar ridge : run the finger down this ridge and the tubercle will be felt 

 some 2 to 3 inches above the condyle, more marked from the presence of a shallow 

 groove just above it. The groove is for a muscular artery, and the tubercle is for the 

 attachment of the lowest fibres of the septum, which is pierced by the artery. The 

 tubercle is not to be confounded with a marking occasionally present at a slightly 

 lower level and more externally, made by the fascia of Vastus externus. 



FIG. 1 20. Posterior aspect of right femur to show linea aspera, etc. The left figure shows how the external 

 intermuscular septum reaches the bone, being continuous above with the tendon of Gluteus maximus, 

 and below this with the deep aspect of the ilio-tibial band. It separates Vastus externus from the 

 short head of Biceps, which is indicated by the thick black line (B-) between the septum and Adductor 

 magnus : observe that the septum is pierced close to its lower end by a muscular artery, and that the 

 Biceps is not (as a rule) so pierced. On the back of the bone (right figure) a small tubercle marks the 

 end of the line of the septum, which runs up to the Gluteal ridge, and a groove marks the position of 

 the piercing artery and hence the lower end of the origin of Biceps ; the little tubercle is not to be con- 

 founded with a rough spot (a) due to aponeurotic fibres in Vastus externus. The remainder of the 

 linea aspera is seen analysed into the districts into which the tendons are inserted which are responsible 

 for its formation, and on each side of it the origins of the two Vasti are shown as interrupted lines ; 

 in its lower part (dotted) the Vastus internus arises from the tendon of Adductor magnus, and not 

 from the bone. Other areas on the posterior aspect of the bone are : A. covered by Gluteus maximus ; 

 B, popliteal surface, in relation with vessels and popliteal fat ; C and D, covered by Vastus internus 

 and externus respectively. In the upper part of the left figure the Ilio-Psoas is seen in position, showing 

 how the internal circumflex artery is kept away from the bone by it (compare with Fig. 121). The 

 lower end of the bone has the origins of Gastrocnemius marked out ; observe how much of each head 

 and of Plantaris arises from the condylar capsule. The condylar capsules cover in the condylar recesses 

 of the joint, and the interval between them is occupied by the crucial ligaments ; in the figure, however, 

 these have been covered in by the lig. posticum which is really an expansion from tendon of Semi- 

 membranosus. The cut tendon is shown, lying against the condylar capsule, having first crossed part 

 of the origin of inner head of Gastrocnemius. The inner head comes down to the inner side of the 

 tendon, so that a bursa is necessary between them, and this must lie on the capsule, through which it 

 sometimes reaches the joint cavity. Semimembranosus expands at its insertion and its front fibres 

 pass under the internal lateral ligament, a bursa intervening. Tendon of Popliteus comes through the 

 outer and back part of the outer capsule (6), deep to the ext. lat. lig. ; the latter is covered by tendon 

 of Biceps, with a small bursa interposed. 



Short head of Biceps is just internal to the line of the septum, extending from the 

 gluteal ridge to the slight groove above the tubercle, for the artery runs below the 

 origin of Biceps, though it pierces the septum. Sometimes the origin is prolonged a little 

 upwards, in which case it must of course run internal to the gluteal ridge. Adductor 

 mugnus extends as high as the level of the top of the small trochanter, but occasionally 

 falls short of this : it extends down to the Adductor tubercle, and as a rule no definite 



