

THE TARSUS 



271 



bone: the rest of this surface is rough for the attachment of ligaments and part 

 of the tendon of the Peronseus longus. The anterior surface, kidney-shaped and 

 much larger than the posterior, articulates with the first metatarsal bone. The 

 posterior surface is triangular, concave, and articulates with the most medial and 

 largest of the three facets on the anterior surface of the navicular. The plantar 

 surface is rough, and forms the base of the wedge; at its back part is a tuberosity 

 for the insertion of part of the tendon of the Tibialis posterior. It also gives 

 insertion in front to part of the tendon of the Tibialis anterior. The dorsal surface 

 is the narrow end of the wedge, and is directed upward and lateralward; it is 

 rough for the attachment of ligaments. 



Articulations. The first cuneiform articulates with four bones: the navicular, second cunei- 

 form, and first and second metatarsals. 



The Second Cuneiform Bone (os cuneiforme secundum; middle cuneiform) (Figs. 

 280, 281). The second cuneiform bone, the smallest of the three, is of very reg- 

 ular wedge-like form, the thin end being directed downward. It is situated between 

 the other two cuneiforms, and articulates with the navicular behind, and the 

 second metatarsal in front. 



- Surfaces. The anterior surface, triangular in form, and narrower than the pos- 

 terior, articulates with the base of the second metatarsal bone. The posterior sur- 

 face, also triangular, articulates w r ith the intermediate facet on the anterior surface 

 of the navicular. The medial surface carries an L-shaped articular facet, running 

 along the superior and posterior borders, for articulation with the first cuneiform, 

 and is rough in the rest of its extent for the attachment of ligaments. The lateral 



Tor 1st cuneiform 



For navicular 



For 2nd metatarsal For 3rd cuneiform 



FIG. 280. The left second 

 cuneiform. An t er o-media 1 



FIG. 281. The left 

 second cuneiform. Pos- 

 tero-lateral view. 



surface presents posteriorly a smooth 

 facet for articulation with the third 

 cuneiform bone. The dorsal surface 

 forms the base of the wedge; it is 

 quadrilateral and rough for the at- 

 tachment of ligaments. The plantar 

 surface, sharp and tuberculated, is 

 also rough for the attachment of 

 ligaments, and for the insertion of a 

 slip from the tendon of the Tibialis 

 posterior. 



Articulations. The second cuneiform articulates with four bones: the navicular, first and 

 tl ird cuneiforms, and second metatarsal. 



The Third Cuneiform Bone (os cuneiforme tertium; external cuneiform) (Figs. 282, 

 2S3). The third cuneiform bone, intermediate in size between the two preceding, 

 is wedge-shaped, the base being uppermost. It occupies the center of the front row 

 ol the tarsal bones, between the second cuneiform medially, the cuboid laterally, 

 the navicular behind, and the third metatarsal in front. 



Surfaces. The anterior surface, triangular in form, articulates with the third 

 metatarsal bone. The posterior surface articulates with the lateral facet on the 

 anterior surface of the navicular, and is rough below for the attachment of liga- 

 mentous fibers. The medial surface presents an anterior and a posterior articular 

 facet, separated by a rough depression: the anterior, sometimes divided, articulates 

 with the lateral side of the base of the second metatarsal bone; the posterior skirts 

 the posterior border, and articulates with the second cuneiform; the rough depres- 

 sion gives attachment to an interosseous ligament. The lateral surface also pre- 

 sents two articular facets, separated by a rough non-articular area; the anterior 

 facet, situated at the superior angle of the bone, is small and semi-oval in shape, 

 and articulates with the medial side of the base of the fourth metatarsal bone; 



