ACTIOXS OF THE MUSCLES OF THE LEG AND FOOT. 2S9 



the dorsal muscles are visible both from above and below. Two muscles 

 are found in each space, except the innermost, in which there is only one. 



Fig. 200. 



Fig. 200, A.— The Doksal Interosseous 

 Muscles FROii above. ^ 



1, 2, 3, 4, the several dorsal inter- 

 osseous muscles : the final insertion of 

 the extensor tendons into the phalanges 

 of the toes is also shown in this figure. 



B.— TnE Plantar Interosseous Mus- 

 cles FROJi below. 

 1, 2, 3, the three plantar interossei ; 

 this figure also shows the long and short 

 ].lantar ligaments, and the insertion of 

 the tendon of the peroneus longus mus- 

 cle into the first metatarsal bone. 



The dorsal interossei lie one 

 in each interspace. Each muscle 

 arises by two heads from the ad- 

 jacent sides of two metatarsal 

 bones ; their muscular fibres are 

 attached pennately on the two 

 sides of a central tendon whicli 

 is inserted partly into the dorsal 

 fiurface of the first phalanx and 

 partly into the extensor apo- 

 neurosis of the toe to which each belongs. The first two are inserted 

 one on each side of the second toe ; the third and fourth are severally 

 inserted on the outer sides of the third and fourth toes. At the proxinial- 

 ends of each muscle there is an interval between the two origins 

 giving passage to perforating arteries as in the hand. 



The i^lanlar interossei arise from the inner and under surfaces of the 

 third, fourth, and fifth metatarsal bones, and are severally inserted in 

 a manner similar to the dorsal interossei, partly into the inner sides of 

 the first phalanges of the third, fourth, and fifth toes, and partly into, 

 the extensor tendons of these toes. 



Nerves. — The flexor brevis digitoiaun. the abductor, the flexor brevis pollicis. 

 .and the two inner lumbricales, are supplied by the internal plantar nerve ; all 

 the other plantar nauscles. including the flexor acccssorius and the interossei, are 

 supplied by the external jilantar neiTe. 



Actions of the Muscles of the Leg and Foot. — There is only one muscle of the 

 leg, viz., the jwjdlfcn.s, which acts on the knee-joint alone. Its principal action is 

 that of a rotator inwards of the lower leg ; and it is interesting to observe that, 

 •while inward rotation of the leg at the knee-joint occurs only in flexion, it is 

 in that position only that the tendon of the popliteus lies in its groove on the 

 femur. 



It may here be observed that owing to the difference in the direction of the 

 "bend at the ankle, as compared with that at the wrist-joint, some confusion is 

 apt to arise in the description of the action of the muscles of the leg upon the 

 foot. As it is obvious from morphological considerations, that the anterior sm-- 

 face of the leg and the dorsal surface of the foot belong to the general crfcuxor 

 sui-face of the limb, corresponding with the back of the foreann and the dorsum 

 of the hand ; and that the back of the leg and the sole of the foot belong in the 

 same way to tke general jifxor gui-facie corresponding with the front of the fore- 



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