The Lower Extremity and Pelvis 



163 



bone below. Here the other extensor structures come into relation with the bone 

 (Fig. 132). In fact, all the structures that pass down over the front of the ankle joint 

 to reach the foot lie in front of the tibia, with the exception of the anterior peroneal 

 artery, which usually descends in front of the fibula. 



The deep fascia is attached to the front margin, thickening below to form the upper 

 part of annular ligament (see later, p. 178). From this it passes outwards round the 

 leg, covering it behind and passing to the postero-internal border. Thus the inner 

 surface of the shaft is only covered by superficial fascia and skin, and in this the saphena 

 vein passes upwards and backwards on the lower fourth of the bone (Fig. 134) before 

 it comes to lie on the deep fascia. It must be noticed, however, that the deep fascia 

 is carried on to this surface by the tendons of Sartorius, etc., in the upper part : it 

 covers these in and is blended with them. As Sartorius gives an expansion down into 

 the deep fascia below, it is apparent that the line of its 

 insertion must pass backwards and downwards to reach 

 the line of fascial attachment on the inner border. 



These tendons are inserted in the order they would 

 take when the leg is bent (Fig. 135). They pass over the 

 internal lateral ligament, with an intervening bursa. 

 Their markings of insertion can usually be felt if not 

 seen on the bone : the small extension of ossification 

 into them to form a secondary marking may be associated 

 with their direction, for they lie on the periosteum and 

 practically in the plane of its surface, and thus do not 

 tend to pull it from the bone, as would be the case if they 

 acted at an angle. 



Behind the tendons, on the inner side of the upper end 

 of the shaft, there is to be found a well-marked roughened 

 area for attachment of a strong aponeurotic sheet of fibres 

 derived from the expansion of Vastus internus. The area 

 is shown in Fig. 134. 



This set of fibres runs to the bone parallel with the 

 front border of the internal lateral ligament, as seen in 

 the central figure, and is directly continuous with more 

 scattered fibres running to the bone above it, and above and 

 in front of it : it is crossed by the three tendons, and the 

 bursa between them and the ligament extends also on to 

 the expansion. The marking for the ligament is behind and below that for the 

 aponeurotic fibres : the inferior internal articular artery turns up above it. 



The upper and more scattered fibres are attached to the epiphysis like the outer 

 expansion, but as the whole internal structure is composed of expansion of the internal 

 Vastus it must be considered as a functional capsule and such a term not applied only 

 to the deeper fibres. The deep fascia covers it and is blended with it, so that the line 

 of the fascia is as shown in the figure. 



The interosseous border is very variable in its position in its upper part, depending 

 on the size of the Tibialis posticus : this muscle varies in size independent of the general 

 muscularity of the individual. The muscle arises from the back of the interosseous 

 membrane, and is covered on its posterior surface by an aponeurosis, which is con- 

 tinued as a fascial covering over the upper end of the muscle to join the membrane. 

 The covering aponeurosis is attached internally to the tibia and makes the vertical 

 line on it. Therefore the area of origin of the muscle lies between the interosseous and 



FIG. 135. When the leg is 

 bent, in the usual posi- 

 tion, the Sartorius, S., 

 from the front, the Gra- 

 cilis, G., from the inner 

 side, and the Semitendi- 

 nosus, T., from the back 

 of the thigh, reach the 

 tibia in their proper 

 order. When the leg is 

 extended in the upright 

 position, their insertions 

 are brought forward, 

 and the more posterior 

 position becomes the 

 lower, i.e., Semitendi- 

 nosus is inserted below 

 Gracilis, while Sartorius 

 is above as well as 

 superficial owing to its 

 fascial -expan sion . 



