MUSCLES OF THE FOOT. 



357 



now can be more evident or more beautiful 

 than the design manifested in this simple 

 arrangement of the foot! Man is physically 

 as well as morally intended to carry him- 

 self erect. The breadth of his base was ne- 

 cessary for his continued support ; the strength 

 of it is called for on account of the great 

 weight which erect progression throws upon 

 it. Its arches were essential not only to give 

 lodgment and defence to the vessels and nerves 

 of the plantar region, but, by the peculiarity 

 of their construction, to admit of a certain 

 degree of elastic yielding, which greatly dimi- 

 nishes the shocks from violent efforts in leaping, 

 running, &c. The shortness of the toes, aug- 

 mented by the depth of the webs, shows that pre- 

 hension forms no part of the design of the foot, 

 while the size of the first toe, and its connexion 

 with the others, points it out as the principal 

 instrument of progression, to which the rest 

 are auxiliary. The analogies between the foot 

 and the hand are striking; they have the same 

 general arrangement of bones and muscles, 

 and even the arteries and nerves, the joints 

 and ligaments, are in many respects similar, 

 but in the particulars just mentioned the dif- 

 ference is strikingly obvious and important, 

 and just in these respects it is that the feet of 

 the Quadrumana also differ from those of man, 

 showing a difference in their intended action, 

 the erect position, at the utmost being only 

 occasional, not being the natural habit, but the 

 foot being prepared and adapted for grasping 

 and clinging, for which the human foot is 

 quite unfit. 



The construction of the arches of the foot 

 requires a few words. They are two in number, 

 a transverse and a longitudinal one. The latter 

 of these is principally found along the inner 

 edge of the foot, and as we pass towards the 

 outer side the longitudinal arch gradually 

 shortens and becomes more flattened, until at 

 the outer side the arch is entirely lost, the 

 bones of the tarsus and metatarsus resting 

 through their whole length upon the ground. 

 This is to a certain degree necessary from the 

 construction of the toes, these being weaker 

 and shorter, as well as their metatarsal bones, 

 as they are further from the great toe ; as their 

 strength therefore diminishes, the corresponding 

 part of the arch is shortened and flattened, and, 

 consequently, less strain is thrown upon them, 

 until, at the line of the little toe, the arch is 

 ob'itei-ated, and what weight is resting here 

 comes at once upon the ground. But from 

 this construction it follows that the longest and 

 the highest line of this arch falls upon the 

 strongest metatarsal bone and longest toe, and 

 that whatever yielding there is occurring in the 

 entire longitudinal arch is greatest in this part 

 of it. This is, indeed, proved by the fact that 

 the length of the foot in a sound state is in- 

 creased in the line of the great toe to the extent 

 of several lines, by resting the weight of the 

 body upon the foot, whereas it is not at all 

 increased in the line of the little toe. When, 

 therefore, the arch yields to the superincumbent 

 pressure, it does so chiefly along the inner side, 

 and the foot is thus, lo a certain degree, twisted. 



the inner malleolus approached nearer to the 

 ground, while the outer is very little, if at all, 

 lowered. This explains to us the reason of the 

 scaphoid and inner cuneiform bones projecting 

 as they do in the flat foot, and of the pain ex- 

 perienced on the inner side of the foot in the 

 same deformity in all efforts to raise the heel in 

 walking. It may also in some degree account 

 for the fact of the more frequent occurrence of 

 dislocation of the tibia at the ankle-joint in- 

 wards than outwards, the arch of the foot 

 yielding first to the force of the accident on the 

 inner side, and thus tilting the whole ankle- 

 joint inwards. The utility in walking of the 

 'form and relation of the various parts of the 

 foot now mentioned is readily seen when we 

 unite the consideration of the structure of this 

 arch with the combined action of the gastro- 

 cnemii upon the heel, and of the peroneus 

 longus upon the outer side of the foot. The 

 united action of these muscles throws and 

 sustains the whole weight upon the strongest 

 and most elastic part. 



Whatever has been said of the utility of the 

 longitudinal arch applies equally to the trans- 

 verse arch, which is supplementary and auxiliary 

 to the former in all its uses. 



( A. T. S. Dodd.) 



FOOT, MUSCLES OF THE. In speaking 

 of the muscles of the foot we necessarily under- 

 stand not merely those muscles which are si- 

 tuated upon the foot, but those muscles pecu- 

 liarly belonging to it, which are concerned in 

 producing its motions wherever situated. The 

 muscles of the foot, in this sense, are partly 

 situated upon the leg and partly upon the foot, 

 and should, in a physiological view, be consi- 

 dered together, that we may the better under- 

 stand their separate and combined functions. 

 We shall therefore, in this, as in other ana- 

 tomical articles, first give the descriptive 

 anatomy of the muscles situated upon the foot, 

 and then examine their functions in connexion 

 with those others whose action is upon the 

 joints of the foot, and which are therefore 

 strictly muscles of the foot, but which are 

 anatomically described elsewhere. (See LEG, 

 MUSCLES OF THE.) 



The proper muscles of the foot are, 1. those 

 on the dorsum ; 2. those on the sole. 



The muscles on the dorsum pedis are the ex- 

 tensor brevis digitorum and the dorsal interossei. 



1. The extensor brevis digitorum (Fr. pe- 

 dieiuc). This is a short flat muscle, situated 

 upon the outer side of the tarsus and meta- 

 tarsus. It arises by fleshy and tendinous 

 fibres from the upper and anterior part of the 

 os calcis, in the hollow between that bone and 

 the astragalus (creux astragalo-calcanien), also 

 partly from the os cuboides. It immediately 

 forms a broad fleshy belly, the fibres of which 

 pass forwards and inwards, and divide into 

 four portions, from each of which proceeds a 

 slender tendon. These four tendons, of which 

 the two internal are the strongest, cross under 

 those of the long extensor of the toes, opposite 

 the heads of the metatarsal bones. Of the^e 

 tendons the internal is inserted into the base of 



