THE CUBOID BONE. 263 



The lateral surface displays a facet arranged along its posterior border, and usually 

 somewhat constricted in the middle ; this is for the third cuneiform. In front of 

 this the bone is rough for the interosseous ligaments which bind the two bones 

 together. The posterior surface is provided with a triangular facet slightly concave 

 from above downwards ; this rests on the intermediate articular surface on the 

 anterior aspect of the navicular. In front the bone articulates by means of a 

 wedge-shaped facet with the SECOND CUNEIFORM CUBOID IV METATARSAL 



base of the metatarsal bone 

 of the second toe. 



The third cuneiform, 

 intermediate in size between 

 the first and second, is also 

 of a fairly typical wedge 

 shape ; though its antero- 

 posterior axis is not straight 



but bent, so that the anterior 



P' i i FIG. 267. RIGHT THIRD FIG. 268. RIGHT THIRD 



CUNEIFORM (Medial Side). CUNEIFORM (Lateral Side). 



slightly medially. Its dorsal 



surface, which corresponds to the base of the wedge, is slightly convex from 

 side to side, and provides attachments for the dorsal ligaments. Its inferior 

 or plantar aspect forms a rough blunt edge, and serves for the attachment of 

 the plantar ligaments. Its medial surface, of quadrilateral form, displays two narrow 

 articular strips, placed along its anterior and posterior borders respectively, each 

 somewhat constricted in the middle. The anterior facet articulates with the lateral 

 surface of the base of the second metatarsal bone, the posterior with the lateral 

 surface of the second cuneiform. The rough non-articular surface, which separates 

 the two elongated facets, serves for the attachment of ligaments. The lateral 

 aspect of the bone is characterised by a large circular or oval facet, placed near 

 its posterior border, for articulation with the cuboid ; in front of this the anterior 

 border is lipped above by a small semi-oval facet for articulation with the media] 

 side of the base of the fourth metatarsal. The rest of the bone around and 

 between these facets is rough for ligaments. Posteriorly the bone is furnished with 

 a blunt, wedge-shaped facet for articulation with the corresponding area on the 

 anterior surface of the navicular. Below this the surface is narrow and rough for the 

 attachment of ligaments. The anterior surface of the bone articulates with the 

 base of the third metatarsal by an area of triangular shape 





Os Cuboideum. 



The cuboid lies on the lateral side of the foot, about its middle, articulating 

 with the calcaneus posteriorly and the fourth and fifth metatarsal bones anteriorly. 

 Its dorsal surface, plane in an antero-posterior direction, is slightly rounded from 



I side to side, and provides attachment for ligaments. Its plantar aspect is tra- 

 versed obliquely from the lateral side medially and forwards by a thick and prominent 



: ridge, the lateral extremity of which, at the point where it is confluent with the 

 lateral surface, forms a prominent tubercle (tuberositas ossis cuboidei), the anterior 

 and lateral surface of which is smooth and facetted to allow of the play of 

 a sesamoid bone which is frequently developed in the tendon of the peronseus 



i longus muscle. Anterior to this ridge there is a groove (sulcus peronsei) in which 

 the tendon of the peronseus longus muscle is lodged as it passes across the plantar 

 surface of the bone. Behind the ridge the bone is rough, and serves for the 

 attachment of the plantar calcaneo-cuboid ligament, the superficial fibres of which 



: pass forwards and are attached to the summit of the ridge. The lateral aspect of 

 the bone is short and rounded, and is formed by the confluence of the dorsal and 

 plantar surfaces : it is more or less notched by the peroneal groove which turns round 

 its plantar edge. The medial surface of the bone is the most extensive ; it is easily 

 recognisable on account of the presence of a rounded or oval facet situated near 



