THE LEG 371 



in a strong, stout tendon which joins with the tendon of 

 the gastrocnemius to form the tendo calcaneus (Achillis). 

 Branches from the tibial nerve supply the soleus. It is a 

 plantar flexor of the foot. 



Tendo Calcaneus (Achillis). This is the most powerful 

 tendon in the body. It narrows as it descends, but near the 

 heel it again expands slightly. It is inserted into the middle 

 portion of the posterior surface of the calcaneus. The fleshy 

 fibres of the soleus are continued distally on its deep 

 surface to within a short distance of the heel. A mucous 

 bursa intervenes between the tendo calcaneus and the 

 proximal part of the posterior surface of the calcaneus. 



Dissection. Divide the soleus muscle along its line of origin 

 from the tibia and separate it from the fibrous arch over the 

 vessels and the tibial nerve ; then turn it to the lateral side 

 and secure the branches which the muscle receives from the 

 peroneal and posterior tibial arteries. 



The first fascial septum which stretches across the posterior 

 osteo-fascial compartment is now fully exposed. Note its 

 attachments to the tibia and fibula (see p. 367), and its 

 continuity, distally, with the laciniate ligament. Separate it 

 carefully from the laciniate -ligament, but do not injure the 

 ligament ; then divide it longitudinally along the middle line of 

 the leg and turn the two pieces, one medially and the other 

 laterally. The middle section of the posterior osteo-fascial 

 compartment is now opened up and two muscles, the tibial nerve, 

 the termination of the popliteal artery, the commencements 

 of the anterior and posterior tibial arteries are exposed, the 

 vessels and the nerve being embedded in some loose areolar 

 tissue. The muscle on the medial side is the long flexor 

 of the toes, the muscle on the lateral side is the long flexor of 

 the great toe. In the distal part of the leg, emerging from under 

 cover of the medial border of the tendon of the long flexor of 

 the toes, the tendon of the tibialis posterior will be seen. Clean 

 first the tibial nerve and secure the branches which it gives to 

 the flexor digitorum longus, the flexor hallucis longus, and the 

 tibialis posterior ; they arise as a rule in the upper part of the leg. 

 Next clean the termination of the popliteal artery, the first part 

 of the anterior tibial artery and its fibular and posterior tibial 

 recurrent branches, then the posterior tibial vessels and their 

 branches and tributaries. The peroneal branch of the posterior 

 tibial artery arises about 25 mm. distal to the commencement 

 of the parent trunk, and immediately proximal to the point 

 where the tibial nerve crosses posterior to the posterior tibial 

 artery. It soon disappears under cover of the flexor hallucis 

 longus ; do not trace it at present beyond the point of dis- 

 appearance. After the nerve and vessels are displayed clean first 

 the flexor digitorum longus and then the flexor hallucis longus. 

 When that has been done separate the two muscles and push 

 the flexor hallucis longus laterally, separating its deep surface 

 from the posterior surface of the second fascial septum of the 



