THE CUNEIFORM BONES. 



207 



The internal surface presents a reversed L-shaped articular facet, running along 

 the superior and posterior borders, for articulation with the internal cuneiform^ 

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

 external surface presents posteriorly a smooth facet for articulation with the 

 external cuneiform bone. The superior surface forms the base of the wedge ; it 

 is quadrilateral, broader behind than in front, and rough for the attachment of 

 ligaments. The inferior surface, pointed and tubercular, is also rough for liga- 

 mentous attachment and for the insertion of a slip from the tendon of the Tibialis 

 posticus. 



To ascertain to which foot the bone belongs, hold its superior or dorsal surface 

 upward, the broadest edge being toward the holder: the smooth facet (limited 

 to the posterior border) will then point to the side to which it belongs. 



Articulations. With four bones : navicular, internal and external cuneiform, 

 and second metatarsal bone. 



Attachment of Muscles. A slip from the tendon of the Tibialis posticus is 

 attached to this bone. 



For fourth 

 metatarsal. 



For cuboid. 



For third 

 second metatarsal. metatarsal. 



FIG. 145. The left external cuneiform, 

 nal view. B. Antero-external view. 



Postero-inter- 



THE EXTERNAL CUNEIFORM (Fig. 145). 



The External Cuneiform, intermediate in size between the two preceding, is 

 of a very regular wedge-like form, the broad extremity being placed upward, the 

 narrow end downward. It occupies 



the centre of the front row of the For , 



, i IT . \ for m/ia, cuneiform. 



tarsus, between the middle cunei- 

 form internally, the cuboid exter- 

 nally, the navicular behind, and 

 the third metatarsal in front. It 

 is distinguished from the internal 

 cuneiform bone by its more regular 

 wedge-like shape and by the absence 

 of the kidney-shaped articular sur- 

 face : from the middle cuneiform, 

 by the absence of the reversed L- 

 shaped facet, and by the two articular facets which are present on both its inner 

 and outer surfaces. It has six surfaces for examination. 



The anterior surface, triangular in form, articulates with the third metatarsal 

 bone. The posterior surface articulates with the most external facet of the 

 navicular, and is rough below for the attachment of ligamentous fibres. The 

 internal surface presents two articular facets, separated by a rough depression ; 

 the anterior one, sometimes divided into two, articulates with the outer side of the 

 base of the second metatarsal bone ; the posterior one skirts the posterior border 

 and articulates with the middle cuneiform ; the rough depression between the two 

 gives attachment to an interosseous ligament. The external surface also presents 

 two articular facets, separated by a rough non-articular surface ; the anterior facet, 

 situated at the superior angle of the bone, is small, and articulates with the inner 

 side of the base of the fourth metatarsal ; the posterior and larger one articulates 

 with the cuboid ; the rough, non-articular surface serves for the attachment of an 

 interosseous ligament. The three facets for articulation with the three metatarsal 

 bones are continuous with one another, and covered by a prolongation of the same 

 cartilage ; the facets for articulation with the middle cuneiform and navicular are 

 also continuous, but that for articulation with the cuboid is usually separate. The 

 superior or dorsal surface is of an oblong square form, its posterior external angle 

 being prolonged backward. The inferior or plantar surface is an obtuse rounded 

 margin, and serves for the attachment of part of the tendon of the Tibialis posticus, 

 part of the Flexor brevis hallucis, and ligaments. 



To ascertain to which side the bone belongs, hold it with the broad dorsal 



