236 STATE BOARD OF AGRICULTURE, 



or metacarpal bones in the human skeleton — according to the. foot of the horse 

 ■we may be considering — hind or fore. 



At the lower end of the cannon bone, and jjhiced behind it, we find two 

 small bones, in form of irregular rhotnboids, called tlie sesamoids ; they are 

 firmly attached by ligaments to the cannon bone, above, and to the bones of 

 the digit below. In situ, these bones are covered with cartilage ; their anterior 

 faces serve to increase the articular surfaces of the fetalock joint, wliile the 

 posterior faces form a groove through which passes the tendon of the fiexor of 

 the foot. The sesamoids, by means of their ligamentous attachments and 

 form, at the same time act as braces to tiie fetlock joint, and as a pulley for 

 the flexor tendon. Below the cannon we find the digit, composed of three 

 bones, placed one upon the other, and a small, flat and transversely elongated 

 bone, placed behind the third or last bone of the digit. The three bones form- 

 ing the column of the digit are known as the first, second, and third phalanges, 

 and the small flat bone is called the navicular bone. The first and second 

 phalanges are flattened from before to behind and roughened for the attach- 

 ment of ligaments and tendons. The third phalanx {the os pedis) or pedal hone 

 is often called the coffin bone. It represents the segment of a very short cone, 

 obliquely and irregularly truncated from its summit to its base. Upon the 

 anterior face, and forming the summit of the bone, we find a roughened sur- 

 face on which is inserted the tendon of the extensor of the foot; on the in- 

 ferior, or plantar, face of the bone we find another roughened surface on which 

 is inserted the tendon of the flexor of the foot. On the two faces of the bone 

 we find a multitude of openings, of different sizes, which give passage to blood 

 vessels and nerves entering the substance of the bone. Firmly attached to the 

 sides of the bone we find two elastic bodies, when healthy, in form of elongated 

 parallelograms, called the lateral cartilages. The pedal bone is covered by a 

 dense fibrous tunic, which supports the delicate horn-secreting membrane; 

 a portion of the lateral cartilages is covered by this membrane. The horse's 

 hoof, and indeed that of all solipeds, is secreted or formed by this most deli- 

 cate membrane which covers the fibrous and bony structures we have men- 

 tioned, as a sock does the human foot; it is continuous with the skin of the 

 animal, but in examining it we will find that it is differently arranged in dif- 

 ferent parts of the foot. 



We will commence the study of this membrane with the portion we find at 

 the superior border of the hoof, or the coronet. The coronet is the matrix of 

 the wall of the hoof, and is lodged in a depression which we find in the supe- 

 rior border of this horny case; its inferior border is separated by a white zone, 

 from the portion of the membrane that we find on the anterior face of the 

 pedal bone ; the superior border is limited by a slightly projecting margin. 

 The posterior portions of the coronet are narrower than the middle, and, on 

 arriving at the parts of the foot known as the heels, they are reflected down- 

 wards and then forwards, onto the fibrous frog, where they are lost in the 

 velvety tissue of that part. The surface of the coronet is covered with a mul- 

 titude of thread-like bodies called papillae ; they are largest on the inferior 

 border, and smallest upon the superior border where a layer of very compact 

 horn is secreted. In the natural state the papillos are lodged in the minute 

 pores we find on the superior border of the wall. The structure of the coro- 

 net resembles that of the lower and middle layers of the skin of which it is, 

 in reality, the continuation ; it has a fibrous framework remarkable for its 

 thickness and compactness. It is richly supplied with blood vessels and nerves, 

 which may be traced to the extremities of the papillae. The spaces between 



