OSTEOLOGY. 69 



dented backwards. The in7ier surface for tlie large internal 

 condyle is concave in all directions, larger than the outer 

 surface, and posteriorly continuous with a synovial facet 

 on the posterior surface of the bone, which is in apposition 

 with the inner synovial facet of the ulna. The outer surface- 

 is divided into two parts ; the inner part is largest in every 

 way, and is continuous inwards at the anterior part with 

 the outer half of the articular surface ; outwardly it is con- 

 tinuous with the outer small division. The posterior margin 

 of this surface is continuous with the outer facet, which is 

 on the posterior surface, and articulates with the ulna. The 

 outer circumf erent margin of the whole articulatoiy surface 

 is prominent for attachment of the capsular ligament of 

 the elbow-joint, and both internally and externally below 

 it is a roughened surface (of which the outer is largest) for 

 attachment of the lateral ligaments ; from the outer runs 

 extensor suffraginis, while the inner is separated by a 

 smooth portion of bone with slight transverse grooves, 

 from a roughness on the shaft, to which also the inner 

 lateral ligament is attached, while the tendon of humeralis 

 externus runs under this prolongation of the ligament over 

 the smooth surface to become attached to a roughened 

 space on the posterior surface, which extends as far as the 

 inner margin of the union with the ulna. The anterior 

 surface of this extremity presents a prominent roughened 

 tubercle continuous with the roughened space on the inner 

 part for attachment of flexor brachii. Externally to this is 

 a smooth surface with a few foramina. On the posterior 

 part of the bone, inclined to the outer side below the syno- 

 vial facets for the ulna, is a roughened space, to which 

 the fibrous band between the bones is attached spreading 

 beyond the line of the ulna, on either side, in its attachment 

 to the radius. Below this is the radio-ulnar arch formed 

 by the approximation of smooth parts of the two bones, 

 through which a branch of the radial artery (vein and 

 nerve) passes to flexor metacarpi externus from within out- 

 wards. This space presents below the medullary foramen of 

 the radius, for the artery during its passage gives off the 

 nutritive vessel of that bone. Below this the union of the 

 bones is ossific, except in the young animal, in which it is 

 fibrous. The inferior extremity of the radius articulates 

 with the upper row of bones of the knee, and for this 

 purpose presents three continuous articular facets. The 



