150 



REGION OF THE ANKLE. 



a deep groove, in which two important tendons 

 are contained, those, namely, of the peroneus 

 longus and brevis. They are lodged in a canal 

 which we have already described as formed by 

 the bone and the external annular ligament, 

 and this canal is lined by a distinct synovial 

 membrane reflected upon it from the tendons. 

 Having passed over the ligaments of the outer 

 ankle, the peronei tendons are next applied 

 upon the surface of the os calcis ; and here, 

 though previously in close apposition, and in- 

 deed contained within the same synovial sheath, 

 they become separated by a ridge projecting 

 from the bone. The peroneus longus tendon plays 

 behind it as upon a pulley, and instances have 

 occurred, where, owing to the fracture of this 

 little osseous septum, the peroneus longus has 

 been dislocated forwards upon that of the 

 brevis. It has also happened that both peronei 

 tendons have been dislocated forwards from 

 their groove behind the malleolus, and thrown 

 in front of that eminence. Were such an acci- 

 dent left without surgical interference, it is inte- 

 resting to reflect how completely altered would 

 be the action of these two muscles, if that action 

 were not completely suspended by the inflam- 

 mation and obliteration of the synovial sheath 

 consequent on the accident ; instead of extend- 

 ing the foot and pointing the toe, as they do in 

 their natural state, they would become con- 

 verted into flexors and abductors of the foot. 

 At the posterior part of the region, the tendo 

 Achillis forms a remarkable projection. In our 

 account of the fascia, we have described the 

 sheath within which this tendon is contained. 

 We may further observe that this tendon is 

 separated from the joint, and also from the 

 deep vessels and nerves of the leg, by a consi- 

 derable interval, so that it has frequently been 

 cut across without injury to the articulation or 

 wound of any other important part. Its mode 

 of insertion into the os calcis is also worthy 

 attention; instead of being fixed into the whole 

 posterior surface of that bone, it occupies by 

 its insertion merely the lower half of it ; supe- 

 riorly the bone and tendon are not even in con- 

 tact, for here a distinct synovial bursa is inter- 

 posed between them. The liability of this 

 large bursa to inflammation and effusion should 

 be carefully borne in mind by the surgeon : and 

 he who is aware of its office, placed as a friction 

 roller between the tendon and bone, will duly 

 estimate how much disease of this bursa will 

 impede the motions of progression. Owing to 

 the interposition of the bursa, rupture of the 

 tendo Achillis has occurred even below the 

 upper edge of the os calcis ; and if, having cut 

 across the tendon, we forcibly extend the foot 

 so as to elevate the heel, we shall at once com- 

 prehend how indispensably necessary it is to 

 maintain the extended position in our treatment 

 of this important accident. 



b. Muscles. There arebut few muscular fibres 

 met with in the region of the ankle: the flexor 

 digitorum brevis arises upon the instep ; and 

 posteriorly we find some of the fibres of the 

 flexor poilicis longus, which are here continued 

 down a considerable way upon the tendon. 



r. Arteries. The arteries about the anklp. 



from their liability to injury and disease, become 

 of great interest. Upon the instep the course 

 and relations of the anterior tibial artery de- 

 mand particular attention ; the vessel here 

 does not run exactly in the median line of the 

 foot, but is somewhat nearer to the inner than 

 to the outer malleolus: we may always reach 

 it with perfect certainty, by cutting between the 

 tendon of the extensor digitorum longus, and 

 that of the extensor poilicis ; these overlap it 

 upon either side, and afford considerable protec- 

 tion against wounds or other injuries. Not- 

 withstanding the facility of reaching the vessel 

 in this situation, it is by no means advisable to 

 do so when it is at all possible to avoid it, inas- 

 much as to expose the artery here it is necessary 

 to wound the synovial sheaths, and inflammation 

 and adhesionwould be the probable consequence 

 of such an injury. The branches of the in- 

 ternal, malleulur artery are found upon the 

 inner part of the region, running upon and in 

 front of the inner ankle, and anastomosing with 

 others passing forwards from the posterior 

 tibial, thus insuring a sufficient supply of blood 

 to the joint, even when the trunk of the anterior 

 tibial itself has been tied. But these vessels 

 are of much inferior importance compared with 

 the posterior tibial, whose main trunk lies in 

 the fossa between the heel and the malleolus 

 internus. It is here occasionally the subject of 

 operation, and hence its course and relations 

 should be very carefully noted. We have al- 

 ready enumerated the tendons passing beneath 

 the annular ligament in this situation ; the most 

 anterior is that of the tibialis posticus, imme- 

 diately behind it lies that of the flexor digi- 

 torum, and still more posteriorly, at the interval 

 of about an inch, is found the tendon of the 

 flexor poilicis ; in this interval between the two 

 latter tendons runs the posterior tibial artery, 

 not however equidistant from both, but nearer 

 to that of the flexor digitorum ; it rests upon 

 the tibia and internal tibio-tarsal ligament, and 

 is covered by the integuments and annular 

 ligament ; its venae comites run one upon 

 either side ; and the posterior tibial nerve lies 

 close behind it, but as the vessel descends get- 

 ting gradually to its inner side. Notwith- 

 standing the few coverings of the artery in this 

 situation, yet owing to the heel, the ankle, and 

 the tendo Achillis projecting around, and hearing 

 off as it were those coverings from it, the vessel 

 is here at a considerable depth from the surface; 

 and any one who supposes it can be easily found 

 in the living subject, will form a very erroneous 

 idea of its true position : hence it i< that all 

 good writers on surgical anatomy recommend 

 us to take up the artery in the lower third of 

 the leg, rather than in the calceo-malleolar 

 groove. Several small vessels ramify about 

 the outer ankle, the external malleolar coming 

 from before meets here with the terminating 

 branches of the peroneal artery from behind, but 

 these small vessels are interesting to the sur- 

 gical pathologist ralher than to the regional 

 anatomist or operative surgeon. 



d. Veins. Two veins, the " venas comites," 

 accompany each of the larger arteres : in all 

 operation*, up^n the artery, the close apposition 



