274 



OSTEOLOGY 





of its medial surface, for articulation with the first cuneiform; and two on its lateral 

 surface, an upper and lower, separated by a rough non-articular interval. Each 

 of these lateral articular surfaces is divided into two by a vertical ridge; the two 

 anterior facets articulate with the third metatarsal; the two posterior (sometimes 

 continuous) with the third cuneiform. A fifth facet is occasionally present for 

 articulation with the first metatarsal; it is oval in shape, and is situated on the 

 medial side of the body near the base. 



The Third Metatarsal Bone (os metatarsale 777) (Fig. 286). The third meta- 

 tarsal bone articulates proximally, by means of a triangular smooth surface, 

 with the third cuneiform; medially, by two facets, with the second metatarsal; 

 and laterally, by a single facet, with the fourth metatarsal. This last facet is 

 situated at the dorsal angle of the base. 



For 4th 

 metatarsal 



For cuboid Tuberosity 

 FIG. 288. The fifth metatarsal. (Left.) 



The Fourth Metatarsal Bone (os metatarsale IV} (Fig. 287). The fourth meta- 

 tarsal bone is smaller in size than the preceding; its base presents an oblique 

 quadrilateral surface for articulation with the cuboid; a smooth facet on the medial 

 side, divided by a ridge into an anterior portion for articulation with the third 

 metatarsal, and a posterior portion for articulation with the third cuneiform; on 

 the lateral side a single facet, for articulation with the fifth metatarsal. 



The Fifth Metatarsal Bone (os metatarsale V") (Fig. 288). The fifth metatarsal 

 bone is recognized by a rough eminence, the tuberosity, on the lateral side of its 

 base. The base articulates behind, by a triangular surface cut obliquely in a trans- 

 verse direction, with the cuboid; and medially, with the fourth metatarsal. On 

 the medial part of its dorsal surface is inserted the tendon of the Peromeus tertius 

 and on the dorsal surface of the tuberosity that of the Peronaeus brevis. A strong 

 band of the plantar aponeurosis connects the projecting part of the tuberosity 

 with the lateral process of the tuberosity of the calcaneus. The plantar surface 

 of the base is grooved for the tendon of the Abductor digiti quinti, and gives origin 

 to the Flexor digiti quinti brevis. 



Articulations. The base of each metatarsal bone articulates with one or more of the tarsal 

 bones, and the head with one of the first row of phalanges. The first metatarsal articulates with 

 the first cuneiform, the second with all three cuneiforms, the third with the third cuneiform, the 

 fourth with the third cuneiform and the cuboid, and the fifth with the cuboid. 



