1454 



CLINICAL AND TOPOGRAPHICAL ANATOMY 



from about the middle of the leg. Of the two heads of the gastrocnemius, the medial is seen 

 to be the larger. On either side of the tendon, but more distinctly on the lateral side, where it is 

 less overlapped bj' the gastrocnemius, the soleus comes into view. Its muscular fibres are 

 continued on the deep surface of the tendon to within a short distance of the heel. Between 

 the tendon and the upper part of the os calcis is a bursa, occasionally the seat of effusion, as 

 in gonorrhoea. 



The bones. — Their relative position and curves have been mentioned (p. 1453). Access. — 

 That to the tibia is easy along the medial aspect. The fibula is best explored by a free incision 

 along the line of the posterior peroneal septum, which lies between the peronei and the muscles 

 at the back (p. 1453). The presence of the superficial peroneal (musculo-cutaneous) nerve per- 

 forating the deep fascia in the lower third below and that of the common peroneal (external 

 popliteal) in relation to the neck of the fibula above, must be remembered. Fractures. — When, 



Fig. 1170. — Anastomoses of Tibial Arteries. 



Anterior tibial recurrent- 



A. 



Posterior tibial, giving off muscular and 

 medullary branches 



Tibia - 



Popliteal 



Anterior tibial, giving off posterior tibial 

 — recurrent and superior fibular before 



piercing interosseous membrane and 



anterior tibial afterward 



• Fibula 



■ Peroneal 



Anastomosis of medial malleolar of _ 

 anterior tibial with posterior medial 

 malleolar 



Medial calcanean" 

 Medial and lateral plantar - 



-Anterior peroneal 

 -Posterior peroneal 



Communicating 



Lateral malleolar of anterior tibial 

 joining posterior peroneal 



■ Talus 



"Lateral calcanean 



— Calcaneus 



) 



a.s is most, frctiucnt, Ww tiliia gives way from iiidircsct violence, the fractvn-o is usually at the 

 weakest spot, or the junction of the middle ;irid lower thirds. The line of obli(iuity is generally 

 marked, and from above downward and forward. The lower fragment, i)ulled upward by the 

 F)owcrful culf musclcH, rides behind the upper, which projects forward under the skin. The 

 fibula, bending more than the tibia, snaps at a higiier level. Tenderness on pressure is the best 

 guide here, as it i.s in suspected fractures of the ujjper tibia, transverse from direct violence, 

 he most common variety of fracture of the fibula is that called after Pott, comi)Ucatcd with 

 dis[)l!U'ement of the foot. Here, from abduction of tlie foot, a severe strain is thrown upon the 

 deltoid ligiiiiiont, which gives way; tiie talus (astragalus) is pressed against the lateral malleolus, 

 and the inferior tibio-fibiilar liganients resisting, tli(t fibula yields 5 to 7 cm. (2 to 3 in.) above the 

 ankle, the upp(!r end of the lower fragment heiiig usually (lisi)laced toward the tibia. If the 

 deltoid ligament is strong, the strain often tears off the medial malleolus. The medial margin 

 of the foot is turned toward the ground, the lateral raised. The foot is also displaced backward. 

 On tlie medial side of thr; ankle there is a marked ])rojection of the lower end of the tibia; higher 



