PLATE XXII. 



THE INNER SIDE OF THE KNEE AND POPLITEAL 



SPACE, &c. 



This plate shows a dissection to expose the popliteal space from the inner side, 

 and also exposing the insertion of the gracilis, sartorius, and semitendinosus. A 

 window has been cut in Hunter's canal to show the femoral artery, and also the long 

 -aphelions nerve. 



The origin of the lower fibres of the vastus internus from the tendinous insertion 

 of the adductor magnus is well seen. While dissecting this region compare the 

 difference in level between the origin of the muscular fibres of the quadriceps extensor 

 on the inside and outside, and it will be found that the inner ones arise from the 

 insertion of the adductor magnus nearly down to the condyle, while the external cease 

 much higher up; thus the external are inserted more obliquely than the internal. 

 Bearing in mind that the patella rests more on the outer condyle of the femur than 

 the inner, is not this lower origin of the inner portion of the quadriceps to act as a brace 

 on the patella and counteract the tendency for it to slip still further outwards ? 



The close connection of the insertion of the adductor magnus into the internal 

 condyle, and the origin of the internal lateral ligament just below it, suggests that these 

 two structures might be related, and in a human foetus of the fourth month the 

 adductor magnus will be observed to be inserted into the head of the tibia, while in the 

 young orang it is directly continuous with the ligament, so that there are reasons for 

 considering this ligament as a divorced part of the adductor magnus. 1 



The wide aponeurotic insertion of the sartorius is well known, and in dissecting it 

 the lower part sends a strongish slip into the fascia of the leg, the fibres of which can 

 be traced down nearly as far as the ankle : this may possibly be adduced as the reason 

 why the long saphenous nerve has such an extensive skin supply, reaching as far as the 

 ball of the great toe, thus following the law, that a nerve supplying a muscle sup- 

 plies also the skin over the area of its muscular action. A similar instance occurs in 

 the arm where the biceps is inserted through the bicipital fascia into the fascia of the 

 arm : it is supplied by the musculo-cutaneous nerve, which also supplies the skin over 

 the fascia acted on by the biceps as far down as the wrist. 



Mr. Bland Button, Ligaments Nature and Morphology. 



