The Lower Extremity and Pelvis 



183 



aspect, where they are covered by the extensor tendons, under which the middle bone 

 is crossed by the dorsal vessels and nerve._ The plantar edges of the two outer bones 

 are covered by ligamentous fibres, from which arise fibres of the Adductor obliquus 

 and some Interosseous muscles. 



METATARSUS. 



With the exception of the first, the metatarsal bones are long and slender, with 

 heavy proximal bases and small 



heads compressed laterally. ^BL ^^.-si??;?. t &*&(*&& 



Though in their general ap- 

 pearance like the metacarpals, 

 they can be distinguished from 

 them at once by this lateral 

 compression, for (Fig. 85) 

 whereas the metacarpals are 

 strong bones, broadening to- 

 wards their solid heads when 

 viewed from the dorsum, the 

 metatarsals, seen in this way, 

 exhibit narrowing when the 

 shafts are followed down to 

 their narrow heads. These 

 outer four metatarsals are not 



directly concerned in carrying the weight of the body : this is borne mainly by the 

 first metatarsal supported by the inner cuneiform, while the remainder of the series 

 have their chief function in preserving the balance of the body. Thus the first 

 metatarsal is massive and strong, and the remainder are comparatively slight, 

 contrasting with the metacarpals, which require strength as opponents in the act 

 of grasping. 



First Metatarsal. Shaft markedly concave below, rounded internally and rather 

 flattened externally where the first dorsal interosseous muscle arises. The proximal 



are&s 



levelled off 

 for QuVtrr < 

 Cuneiform' 



Av- mrjfreuntiform 



FIG. 153. Basal end of left second metatarsal. 



FIG. 152. First metatarsal, left side. External view, and base 

 from inner side and from behind. Also a scheme of section 

 showing how the inner side of shaft is subcutaneous and 

 hence convex. 



jOrominfnC 

 pofnC aT upper and 

 outer inglf of trt*>>yj?ir 



urfite . 



end or base is enlarged, especially prominent below, presenting a kidney-shaped, 

 slightly hollowed facet for the inner cuneiform, whose borders correspond with the 

 general shape of the shaft in being convex internally and concave externally. On 

 the inner side of the base, nearer the plantar aspect, is a secondary marking for Tibialis 

 anticus, and on the other side a hollowed mark for Peroneus longus. A marking 

 not often a definite facet is to be found on the outer side of the proximal enlargement 

 showing the area of contact with the second metatarsal, and in its neighbourhood 



