104 
THE ANATOMY OF THE 
bones. Besides these, it must not be forgotten that there are 
four supplemental or sessamoid bones. The phalangeal extremi- 
ties are shorter in the ox than in the horse. The bones of the 
duplicates being similar, a description of one of each will suffice. 
Each suffraginal bone is round and smooth anteriorly and exter- 
nally, and rough and nearly flat posteriorly and internally. Supe- 
riorly it presents three concavities, which receive the correspond- 
ing convexities in each head of the large metacarpal. It has an 
articulation at the upper and outer part of its posterior surface 
with the internal sesamoid. On the upper posterior division 
we find a deep sinus, with two large tubercles on each side. 
Tw o smaller tubercles are found just below, from each of which 
a ridge extends to the condyles of the bone. On each side of 
the lower head two depressions are visible for the attachment of 
ligaments, and two convexities which articulate with the small 
pasterns. 
The ossa sessamoidea may be arranged as the two external and 
the two internal , so that we may name a right and left internal, 
and a right and left external sessamoid. Their anterior surfaces are 
smooth for articulation, their posterior rough for the attachment of 
the suspensory ligament. They are connected to each other by 
firm ligamentous bands. The two external sessamoids are alike, 
with this solitary exception, the left at its outer side is bent ante- 
riorly, to articulate with the right low'er head of the large me- 
tacarpal bone. They are of irregular shape, and present four 
articulating surfaces, two anteriorly with the large metacarpal, 
one laterally with the internal sessamoid, and one inferiorly with 
the suffraginal bone. They are rather thicker than the internal 
sesamoids, and extend more anteriorly, giving thereby great 
security to the joint. 
The internal sessamoids are rather conical in shape, and each 
has two surfaces articulating with the large metacarpal, and one 
laterally with the external sessamoid. 
The os corona , or small pastern , in circumference is equal, 
and in length is two-thirds that of the os suffraginis. Supero- 
anteriorly, we find a tubercle, from which a ridge extends to the 
condyles. This ridge divides the front surface of the bone into 
