THE LEG 379 



covering the superficial muscles of the calf but also with the 

 septum which separates those muscles from the deeper 

 muscles of the leg (see p. 367), and it has been pointed out 

 that the septum takes a more important part in the formation 

 of the ligament than the more superficial layer of deep fascia. 

 Its distal or anterior margin is continuous with the medial 

 part of the plantar aponeurosis, and it gives attachment to 

 the abductor hallucis muscle which is subjacent to that 

 aponeurosis. It is pierced by the medial calcanean branches 

 of the posterior tibial artery and the tibial nerve, and by a 

 communicating vein which connects the great saphenous 

 vein with the venae comites of the posterior tibial artery. 



The dissector should note that under cover of the ligament 

 lie (i) the termination of the posterior tibial artery and the 

 commencement of its two terminal branches, the medial and 

 lateral plantar arteries, with their accompanying veins; (2) 

 the distal part of the posterior tibial nerve and its medial 

 and lateral plantar terminal branches ; (3) the tendon of the 

 tibialis posterior; (4) the tendon of the flexor digitorum longus; 

 (5) the tendon of the flexor hallucis longus. From the medial 

 to the lateral side the structures lie in the following order : 



1. Tendon of tibialis posterior. 



2. Tendon of flexor digitorum longus. 



3. Posterior tibial vessels. 



4. Tibial nerve. 



5. Tendon of flexor hallucis longus. 



The tendons are isolated from one another, and from the 

 vessels and nerve, by septa which pass from the deep surface 

 of the ligament to ridges on the adjacent bones. The septa 

 can be demonstrated by slitting open the ligament for a short 

 distance along the line of each tendon. Each of the three 

 compartments will then be seen to be lined with a glistening 

 mucous sheath, and the dissector should investigate the 

 extent of each sheath as far as possible, with the aid of a 

 blunt probe, for as the sheaths have been freely opened it 

 will not be possible to inflate or inject them. The sheaths 

 end proximally about 25 mm. above the medial malleolus. 

 Distally the sheath of the tibialis posterior reaches to the 

 insertion of the tendon into the tubercle of the navicular 

 bone. The sheath of the flexor digitorum longus extends to 

 about the middle of the length of the foot, and that of the 

 flexor hallucis longus can be traced, under favourable circum- 



