346 THE INFERIOR EXTREMITY 



the dorsum of the foot to reach the lateral four toes. 

 On the dorsum of the first phalanx of each of the medial 

 three of the lateral four toes each slip is joined, on its lateral 

 side, by a tendon from the extensor digitorum brevis. 



The manner in which the four tendons of the long 

 extensor are inserted is similar, in all essential respects, to 

 that in which the corresponding tendons of the fingers are 

 attached, but there are slight differences, and as the dissector 

 of the foot may not have dissected the hand a description 

 of the conditions met with is necessary. The tendons of 

 the extensor digitorum longus go to the second, third, fourth, 

 and fifth toes, and those of the extensor digitorum brevis to 

 the first, second, third, and fourth toes. In the cases of the 

 second, third, and fourth toes the tendons of the long and 

 short extensors unite, and the conjoined tendons form an 

 expansion on the dorsal aspect of the first phalanx. The 

 expansion is joined by the slender tendons of one lumbrical 

 and two interossei, and then it divides into a central and 

 two collateral parts. The slender central part is inserted 

 into the base of the second phalanx; the stronger 

 collateral parts are prolonged forwards, and, after they have 

 united together, they are inserted into the base of the terminal 

 phalanx; thus five tendons gain insertion into the dorsal 

 aspects of the bases of each of the second and terminal 

 phalanges of the second, third, and fourth toes, and move- 

 ments become possible which could not be readily obtained 

 in any other way, for whilst the flexor tendons flex the 

 metacarpo-phalangeal joints the lumbricals and interossei can 

 extend the interphalangeal joints by virtue of their connection 

 with the extensor expansion. In the case of the foot this is 

 not a very important matter, but in the case of the hand it 

 is of extreme importance, for it is only by the means indicated 

 that it is possible to place the fingers in the " writing position," 

 and use them in the usual manner adopted for writing 

 (see p. 178). The extensor digitorum longus is supplied by 

 the deep per oneal nerve. It is an extensor of the interphalangeal 

 and metatarso-phalangeal joints of the lateral four toes and 

 it dorsi-flexes the foot. 



M. Extensor Hallucis Longus. The long extensor of the 

 great toe is placed in the interval between the tibialis anterior 

 and the extensor digitorum longus. In its proximal part it 

 is hidden from view by those muscles, but near the ankle it 



