EXTENSOB MUSCLES OF THE TOES. 



281 



each side, and from the fascia of the leg. The fleshy fibres from this exten- 

 sive origin pass obliquely into a tendon placed on the anterior part of the 

 muscle. This subsequently divides into four slips, which descend through 

 the lower part of the annular ligament, in the same sheath as the peroneus 

 tertius, and on the dorsum of the foot pass respectively to the four outer 

 toes. Not ^infrequently the slip belonging to the fifth toe is separated 

 with that of the peroneus tertius from the rest considerably higher up. The 

 three inner tendons are each joined at the outer side, on the first phalanx, 

 by a tendon from the extensor brevis digitorum : all the four tendons 

 are continued into expansions, which are joined on the first phalanx by 

 tendinous processes from the luinbricales and interossei muscles, and have 

 their middle fibres inserted into the second phalanx ; while their lateral 

 parts unite together and are inserted on the third, in a manner exactly 

 similar to the arrangement of the extensor tendons on the fingers. 



Fig. 214. 



Fig. 214. SUPERFICIAL MUSCLES AND TENDONS ON 

 THE DORSUM OP THE FOOT AND LOWER PART OF 

 THE LEG ANTERIORLY (after Bourgery). J 



a, lower part of the tibia ; &, lower part of the 

 fibula above the raalleolus extern us ; c, inner side of 

 the scaphoid bone ; d, internal cuneiform bone ; 1, 

 lower part of the tibialis anticus muscle ; 1', its tendon 

 descending in the groove of the internal cuneiform 

 bone ; 2, extensor longus pollicis ; 2', its expansion 

 on the dorsum of the great toe ; 3, extensor communis 

 digitorum dividing into its four tendons for the toes ; 

 3', the expansion, and 3", the final insertion of the 

 same upon the second toe ; 4, peroneus tertius ; 4', 

 its expanded insertion on the base of the fifth meta- 

 tarsal bone ; 5, small part of the fibres of the soleus 

 on the inner side of the tibia ; 6, small part of the 

 peroueus brevis ; 7, extensor brevis digitorum, seen 

 below the tendons of the extensor longus and peroneus 

 tertius; 7', 7", on a band of aponeurosis crossing the 

 toes, the first and fourth tendons of the extensor 

 brevis muscle passing to join those of the long ex- 

 tensor ; 8, 9, anterior annular ligament, chiefly in its 

 luwer part, or ligamentum cruciatum ; between 8 and 

 c, the inner and lower band enclosing the extensor 

 loiigus pollicis and tibialis anticus ; below 9, the 

 outer part of the same enclosing the tendons of the ex- 

 tensor communis and peroneus tertius ; 10, 11, dorsal 

 transverse band of the aponeurosis of the foot, uniting 

 the heads of the metatarsal bones. 



The peroneus tertius arises, in continuity 

 with the lower part of the extensor longus 

 digitorum, from the lower fourth of the inner 

 surface of the fibula, from the lower part of 

 the interosseous membrane, and from an 

 aponeurosis which connects it on the outer 



side with the peroueus brevis. The muscular fibres end in a tendon, which, 

 after passing through the annular ligament with the long extensor of the 

 toes, is inserted into the upper surface of the base of the fifth metatarsal 

 bone, and likewise in some instances into the fourth. 



There is often scarcely any line of demarcation between the two preceding muscles. 

 The peroneus tertius is sometimes as large as the extensor longus digitorum, some- 

 times its tendon is as large as those of that muscle combined ; it has been observed 

 to terminate on the fourth metatarsal bone ; and it is sometimes altogether wanting. 



