1 84 



Anatomy of Skeleton 



are impressions for interosseous ligaments. The head has practically no articular 

 surface on its dorsal aspect, only on its plantar side and extremity, that in the former 

 situation being scored by two grooves in which the two sesamoid bones slide that are 

 in the capsule. 



These two bones are the largest sesamoids in the body after the patella, and keep the long 

 flexor tendon away from the head of the bone : they, with the soft tissues covering them, are 



responsible for the plantar prominence of the " ball of the 

 toe," and receive the insertion of the Abductor, Flexor 

 brevis, and Adductors. The inner one is slightly the larger, 

 and there is usually a corresponding difference in the size 

 of the grooves on the head. Sesamoids are occasionally 

 found in the other metatarso-phalangeal joints as in the 

 hand. 



The bone is superficial and can be felt on its 

 dorsal and inner sides, but in the sole it is deeply 

 placed and covered immediately by the short flexor 

 FlG ^bU 5 q tiH y S oUhTbas\ S of S the V n 1 e t ta e of the hallux, and externally gives an extensive 

 tarsals. Left side. The increas- origin to the first Dorsal Interosseous. The com- 

 &1K&aibr ThTwer municating artery runs down in relation with the 

 figure illustrates the increasing proximal part of its shaft on this side. 



sectional obliquity of the shafts 

 from within outwards. 



Second Metatarsal. The longest of the series. 



Base fits in between first and third cuneiforms, so carries facets for these on each 

 side, interrupted by interosseous (tarso-metatarsal) ligaments, in addition to an inter- 

 rupted articulation on the outer side for third metatarsal, and a non-articular area on 

 inner side for first metatarsal. The area just below the facet for the first cuneifor m 

 marks the anterior attachment of " Lisfranc's ligament." The bevelled-off cuneiform 



frrner-tidf 



inner sidle. 



of J** 



FIG. 155. Basal ends of 3rd and 4th metatarsals, with outlines of their respective tarsal surfaces. 



area on the outer side is one of the characteristics of the bone (Fig. 153). The 

 wedge-shaped basal facet is very slightly concave, owing to a small projection of the 

 upper and outer angle. Markings of interosseous ligaments are well developed. The 

 shaft gives origin to no palmar interossei, but to the first two dorsal muscles. 



Third Metatarsal. This articulates with one of the cuneiforms, the external, which 

 supports it, and for which it has a flat triangular basal facet : at the sides are facets 

 for the second and fourth metatarsals respectively, that for the former interrupted 

 and converted into double surfaces by an interosseous ligament, that for the latter 

 single. 



The obliquity of the line of its base is greater than that of the second (see Fig. 154), 

 but not so great as in the fourth metatarsal. 



