6o4 A MANUAL OF ANATOMY 



not previously dissected, is to be followed out. The inferior external and 

 inferior internal articular arteries are to be studied. The popliteal fascia 

 covering the popliteus muscle is to be inspected, noting that it is one of the 

 modes of insertion of the semimembranosus. The fascia is now to be removed, 

 in doing which it should be noted that the superficial fibres of the popUteus 

 muscle take insertion into its deep surface. In the meantime, the exact origin 

 of that muscle cannot be shown, so that the dissector should content himself 

 with showing the tendon after its escape from the interior of the knee-joint, 

 when it is almost immediately replaced by fleshy fibres. 



The sural muscles having been completely turned aside, the expansion of the 

 deep fascia, called the posterior or transverse intermuscular septum, is to be 

 studied. In connection with it the internal annular ligament is to be dis- 

 played (but not opened up as yet) between the internal malleolus and the 

 tuber calcis. In doing so, care must be taken to preserve the calcaneo-plantar 

 branch of the posterior tibial nerve and the internal calcaneal branch of the 

 posterior tibial artery, both of which pierce the ligament. The deep muscles 

 of the back of the leg are to be cleaned, and at the same time the posterior 

 tibial vessels and nerve are to be dissected. The muscles from within outwards 

 are the flexor longus digitorum, tibialis posticus, and flexor longus hallucis. 

 It should be observed that the tibiaUs posticus is covered superficially by a 

 strong aponeurotic expansion, which stretches across between the muscles on 

 either side of it. In dissecting the lower portions of these muscles in the 

 neighbourhood of the ankle-joint, the internal annular ligament is now to be 

 opened, when it will be seen to contain four canals, three of which are fibro- 

 osseous, and one (for the flexor longus digitorum) purely fibrous. The relation 

 of the tendons, posterior tibial vessels, and posterior tibial nerve as they traverse 

 these canals is to be studied, and the synovial sheaths are to be noted. The 

 branches of the posterior tibial artery and nerve are to be displayed. As 

 regards the branches of the artery, they should be dissected in the following 

 order from above downwards, namely, (i) peroneal, of large size, and 

 arising about i inch below the commencement of the posterior tibial ; 

 (2) medullary, for the tibia (of large size) ; (3) muscular ; (4) communicating 

 or transverse, near the ankle, and passing transversely outwards to join a 

 similar branch of the peroneal ; (5) internal malleolar, usually two in number, 

 and passing beneath the tendons behind the internal malleolus to take part 

 in the internal malleolar anastomosis ; (6) internal calcaneal ; and (7) the two 

 terminal branches, internal and external plantar arteries. Two venae comites 

 are to be dissected with the posterior tibial artery, which communicate at 

 frequent intervals by transverse branches placed superficial to the vessel. 

 These venae comites should be shown to join those of the anterior tibial artery 

 at the lower border of the popliteus muscle, and so form the popUteal vein. 

 The peroneal branch of the posterior tibial artery requires special dissection. 

 After reaching the back of the fibula, it sinks deeply and disappears from view, 

 its course being either between the fibula and the flexor longus hallucis, or 

 in that muscle, or in a fibrous canal between that muscle and the tibiaUs 

 posticus. It will next be found becoming superficial about 2 inches above 

 the ankle, where it should be shown to end by dividing into an anterior and 

 a posterior peroneal branch. Two venae comites are to be dissected with the 

 peroneal artery, which end by joining those of the posterior tibial. The 

 following branches of the peroneal artery are to be dissected from above 

 downwards, namely, (i) muscular; (2) medullary to fibula; (3) communi- 

 cating or transverse ; (4) anterior peroneal, disappearing through the inferior 

 hiatus in the interosseous membrane ; and (5) posterior peroneal. The last- 

 named artery is to be shown passing behind the external malleolus on to the 

 outer border of the foot for a variable distance. It will be seen to give off 

 external calcaneal branches, which take part in the external malleolar anasto- 

 mosis, and anastomose across the heel with the internal calcaneal branches 

 of the external plantar. On the outer border of the foot it will be seen again 

 to anastomose with branches of the external plantar. 



Knee-Joint. — The knee-joint is to be dissected before proceeding with the 

 sole of the foot. The muscular and tendinous relations of the joint are to be 



