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Boyer diss 2009 1046..

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could even be described as having the shape of a paisley motif. The surface supporting<br />

the fibular facet is square to rectangular in shape. The articular area itself is restricted to<br />

the dorsal half of this surface. This facet also has a paisley shape; however it is more like<br />

the lateral tibial facet in having the largest girth distally, and margins that converge<br />

proximally. Ventral to the facet itself is a divot for the astragalofibular ligament. The<br />

apex of the triangular surface of the fibular facet stops short of the proximal margin of the<br />

lateral tibial facet, after the two facets diverge around a prominent superior astragalar<br />

foramen.<br />

On the proximal surface of the astragalus, plantar to the superior astragalar<br />

foramen, the area between the two facets increases and develops into an expansive<br />

concavity. This concavity leads to the flexor fibularis groove on the plantar side of the<br />

astragalus. In plantar view the surface of this groove is triangular, with a proximodistally<br />

oriented medial margin formed by the edge of the medial tibial facet, and a more<br />

obliquely running lateral facet formed by the proximal margin of the posterior<br />

astragalocalcaneal (ectal) facet.<br />

Lateral to the flexor fibularis groove, the ectal facet is rectangular, with its narrow<br />

dimension oriented mediolaterally. It is saddle-shaped with a proximodistal concavity<br />

and mediolateral convexity. The first curvature of the saddle is more pronounced than the<br />

second and forms an arc of ~45°. The lateral margin of the ectal facet meets the surface<br />

for the fibular facet at an angle of just over 90°. The axis of the ectal facet diverges from<br />

that of the lateral tibial facet by ~20°, such that the latter is oriented more medially. At<br />

the mediodistal margin of the contact between the ectal facet and the flexoris fibularis<br />

groove is a deep sulcus separating this structure from the middle astragalocalcaneal<br />

341

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