The coffin-bone is contained in the hoof, of the shape of which it in a large measure partakes. It is a porous bone, having a number of holes in its front and sides for the passage of blood-vessels, and is besides generally roughened for the attachment of the sensitive laminae. A pointed process (coronal process) projects upward from the superior border in front, which affords attachment for the tendon of the extensor pedis muscle.

Os Coronae and Os Naviculare (Anterior Aspect).

Fig. 305. - Os Coronae and Os Naviculare (Anterior Aspect).

Os Pedis (Plantar Aspect).

Fig. 306. - Os Pedis (Plantar Aspect).

A, A Inferior Border. B Semilunar Crest. c Plantar Foramina. D, D Retrossal Processes.

The under surface is concave, and presents (1) a crescentic ridge (semilunar crest) to which the tendon of the flexor pedis is attached; (2) behind this two considerable openings (plantar foramina), through which pass the plantar arteries and nerves; (3) still farther back a roughened surface, to which the inferior ligament of the navicular bone is connected. The upper surface is divided by a slight ridge into two shallow cavities, with which the lower extremity of the coronet bone articulates. At the posterior border of this surface a narrow, smooth, transverse space is provided for the articulation of the navicular bone with the foot - bone. Projecting backward from the inferior border behind are two bony processes, one on either side, termed aloe, or wings.