Fig. i88. Posterior Aspect of Leg. Deep Layer, Internal Popliteal 



Nerve. 



After removal of tlie Superficial Fascia, a large piece has been cut out of the 

 Gastrocnemius and Soletis Muscles, the heads of origin of the Gastrocnemius 

 have been thrown outwards. By further removal of the Deep Fascia, the large 

 Vessels and Nerves have been exposed. An incision through the fascia covering 

 the Popliteus Muscle has exposed the Bursa under the Semimembranosus Muscle. 



The arrangement of the muscles on the back of the leg is very simple: 

 a Superficial Layer formed by the Gastrocnemius, Soleus and the slender Plantaris; 

 a Deep Layer formed by the Posterior Tibial, Long Flexor of Toes and Long 

 Flexor of Big-Toe. On this latter group lie the important Nerves and Arteries, 

 which are quite separated from the Superficial Layer of muscles by the Deep 

 Fascia of the Leg (v. Figs. 185, 186). Between the Deep Fascia of the leg and 

 the Superficial Muscles, loose connective tissue, favourable to the spread of 

 Cellulitis is found. 



In order to allow the vessels and nerves, leaving the Popliteal Space, to 

 reach the deep aspect of the superficial muscles an aponeurotic opening is formed 

 by the Soleus i. e. an arch is thrown across from its Tibial to its Fibular Origin 

 under which the above mentioned structures pass. 



At the lower border of the Popliteus Muscle, the Popliteal Artery divides 

 into Anterior and Posterior Tibial Arteries (occasionally this division takes place 

 at a higher level). The Anterior Tibial Artery (the smaller branch), passes directly 

 over the upper border of the Interosseous Membrane to the Anterior Aspect of 

 the Leg ; the Posterior Tibial Artery passes under the arch of the Soleus, approaches 

 the inner side of the limb and lies in its outer third under the skin between the 

 Tendons on the Long Flexor of the Big-Toe and the Long Flexor of the Toes; 

 together with these tendons it passes behind the Internal Malleolus into the sole 

 of the foot. The chief branch from this vessel is the Peroneal Artery which runs 

 outwards through the arch of the Soleus, under cover of the Fibular origin and 

 the muscular belly of the Long Flexor of the Big Toe, to near the ankle where 

 it emerges and terminates by giving off a Perforatmg Branch to the Anterior 

 Tibial Artery and a large Communicating Branch (sometimes double) to the 

 Posterior Tibial Artery or the outer side of the heel. 



The Posterior Tibial Nerve runs along the outer side of the Artery, and 

 after giving off numerous branches, passes with it under the Internal Annular 

 Ligament to the sole of the foot. 



Deeply situated on the Interosseus Membrane lies the Posterior Tibial 

 Muscle. As the Tibia is subcutaneous throughout its whole length, the structure 

 of the leg is convenient for extensive operations. The Fibula is readily exposed 

 after removal of the Soleus Muscle, but care must be taken in the neighbourhood 

 of its head to avoid injury to the External Popliteal Nerve. 



