Fig. 7.
Os pedis seen in profile and in front; a, anterior face with pyramidal eminence above; b, joint-surface; c, wings or branches of hoof-bone; d, notch which, by the attachment of the lateral cartilage, is converted into a foramen and leads to e, the preplantar fissure.
Fig. 8.
Lower surface of hoof-bone; a, anterior portion covered by the velvety tissue of the sole; b, wing of the os pedis; c, semilunar crest, to which the perforans tendon attaches; d, plantar fissure leading to e, plantar foramen.
The right and left hoof-bones are also, as a rule, easily distinguished by variations in the surfaces of wall and sole. The shape of the os pedis corresponds to the form of the horny box or hoof, and therefore a knowledge of this bone is absolutely necessary.
The navicular bone (os naviculare, nut-bone, [Figs. 9] and [10]) is an accessory or sesamoid bone to the os pedis. It is a small bone, transversely elongated and situated behind and below the os pedis and between the wings of the latter. It adds to the articular surface of the pedal joint. Its under surface is smooth, and acts as a gliding surface for the perforans tendon, which is quite wide at this point.
Fig. 9.
