60 OSTEOLOGY OF THE HORSE. 



it passes the lateral artery, to be conducted by the groove leading 

 from it to a foramen (aforementioned) in the wall. 



Connexion — With the coronet and navicular -bones, and with 

 the hoof. 



Particularities. — The coffin is a bone of a soft, i. e. of a spongy, 

 fragile texture ; and its intrinsic stability is yet further reduced 

 by the canals pervading its interior for the transmission of blood- 

 vessels and nerves. The very reverse of this is the case with the 

 pastern and coronet bones: they (particularly the latter) are re- 

 markable for compactness and solidity of substance. 



THE NAVICULAR OR SHUTTLE BONE*. (OS NAVICULARE.) 



Situation — At the back of the coffin-joint, into whose compo- 

 sition it enters. 



Form — Semi-lunar : its lunated border, however, will not make 

 above one-third of a circle of such dimensions. 



D«t;is?o«— Into two surfaces ; two borders ; and two extremi- 

 ties. 



Surfaces. Tlie superior bears a corresponding aspect to the 

 articulatory surface of the coffin bone, having two superficial la- 

 teral depressions, with an eminence imperceptibly rising between 

 them. Dividing the entire articular surface, formed by the two 

 bones, for the reception of the coronet bone, into five parts, the 

 navicular forms about two divisions. — llie inferior surface is also 

 articulatory ; and also exhibits lateral depressions, but still more 

 superficial than the suj)erior, with an eminence across the middle, 

 narrower and better marked than that above. Over this part 

 plays the tendo perforans. 



Borders. — The lunated, broadest in the middle, narrowing 

 towards the extremities, consists, superiorly, of a smooth narrow 

 slip of surface along the middle, which is adapted to the bevelled 

 portion of the articulatory surface of the coffin bone; and, below, 

 of a fluted porous part, from which a broad ligament runs to the 

 coffin. — T/ie straight border is thin, compared to the opposite one ; 

 and is, superiorly, rough and porous, where the posterior ligament 

 is attached; inferiorly, smooth and lipped, and continuous with 

 the surface opposed to the tendon. 



'The extremities, directed, one outward, the other inward, are 

 obtusely pointed ; and are fixed by lateral ligaments to the 

 coffin bone. 



n.— THE HIND EXTREMITIES. 



Situation — Connected with the posterior parts of the trunk, 

 which they support. 



* Sainhel calls it " The Articular Bone."— Girard considers it as a sesa- 

 moid bone. — (^ur old farriers, in their profound ignorance, have mistaken it 

 for a production of disease, and described it as " the quUtor bone." ! 



