THE LOWER LIMB '603 



skin is to be reflected from the back of the leg. The terminal distribution 

 of the small sciatic nerve having been revised, the dissector should trace the 

 ramus communicans tibiahs and ramus communicans fibularis nerves to the 

 centre of the calf, the former lyang in the median groove of the gastrocnemius, 

 and the latter descending obUquely inwards over the outer head of that 

 muscle. At or about the centre of the calf these two nerves will usually be 

 found to unite, and so form the external or short saphenous nerve. This 

 ner\'e, along \v-ith the short saphenous vein, should be followed superficial to 

 the deep fascia downwards and outwards along the outer side of the tendo 

 Achillis (the nerve meanwhile gi\'ing branches to the integument of the lower 

 half of the back of the leg), then behind and below the external malleolus (in 

 which situation the nerve suppUes calcaneal and malleolar branches), and 

 subsequently along the outer border of the foot. Communications between 

 the short saphenous vein and the long saphenous vein are to be sought for, 

 as well as communications between the former and the deeply-seated veins 

 which accompany the posterior tibial and peroneal arteries. 



The deep fascia of the back of the leg is next to be dissected, and thereafter 

 the gastrocnemius muscle is to be studied. The inner head of the muscle 

 having been previously cut in connection with the dissection of the lower part 

 of the popliteal space, the outer head is now to be divided, and both heads are 

 to be reflected upwards in order to show the exact origin of each, that of the 

 inner head lying obUquely, whilst that of the outer head Ues vertically. The 

 popUteal bursa, which separates the inner head from the semimembranosus, 

 should be sought for, and its relation to the synovial membrane of the 

 knee - joint examined. In the outer head of the muscle will be found a 

 sesamoid fibro-cjirtilage (sometimes ossified). The belly of the gastrocnemius 

 and its tendon is to be reflected downwards as far as the commencement of 

 the tendo Achilhs. The plantaris is then to be dissected, and its long, 

 narrow tendon should be taken between the index-finger and thumb of each 

 hand and stretched laterally to demonstrate its distensibihty. The soleus 

 is next to be dissected, and the fibrous arch over the posterior tibial vessels 

 is to be shown, with fibres of the muscle springing from it. A branch from 

 the internal popUteal nerve is to be found entering the superficial surface of 

 the muscle near its upper border. The other nerve-supply from the posterior 

 tibial will only come into view as the muscle is being reflected. The tendon 

 of the soleus is to be shown joining that of the gastrocnemius to form the 

 tendo AchilUs. The aponeurotic appearance presented by the deep surface 

 of the gastrocnemius and the superficial surface of the soleus is to be noted. 

 The tendo AchilUs is to receive careful attention. 



Before the soleus is disturbed, the hollow on either side of the tendo Achillis 

 is to be noted. In the outer hollow the short saphenous vein and nerve 

 have been already dissected, their position being here superficial. Lying 

 deeply in the hoUow on the inner side of the tendon are the posterior tibial 

 vessels and nerve. A Umited opening should be made in the deep fascia to 

 show the exact position and relations of these structures. The soleus is now 

 to be stripped from its tibial and fibular origins and turned downwards. In 

 the course of this dissection a branch from the posterior tibial nerve is to be 

 shown entering the deep surface of the muscle about the centre of the leg. 

 The tendo AchilUs having been tur^^ed downwards, the large quantity of fat 

 beneath it is to be observed, and the bursa between the tendon and the upper 

 zone of the posterior surface of the tuber calcis is to be shown. By dissecting 

 into the deep surface of the soleus, the arrangement of its very short fibres 

 will be brought into view. 



The lower part of the popUteal vessels and internal popUteal nerve, though 

 previously dissected, should now be revised. The di\'ision of the artery into 

 anterior tibial and posterior tibial at the lower border of the popUteus muscle 

 should be noted. The commencement of the anterior tibial artery is to be 

 dissected, shovdng the vessel passing forwards between the two heads of the 

 tibialis posticus, and between the tibia and fibula. Its branches in this situa- 

 tion are to be shown, namely, posterior tibial recurrent (inconstant), and 

 superior fibular. The nerve to the popUteus from the internal popUteal, if 



