OSTEOLOGY. 91 



semilunar cartilages. Beliind this it is concave and per- 

 forated, affording attachment to the posterior ligament of 

 the inner cartilage, while to its junction with the posterior 

 margin are^ attached the postero -inferior ligament of the 

 outer cartilage and the other crucial ligament. The inner 

 side of the spine is by far the most prominent, and its 

 external surface is articulatory continuous v/ith the inner 

 articulator y facet, which is ovoid, bounded by a roughened 

 margin and lying in contact with the under surface of the 

 inner cartilage and with the inner condyle of the femur. 

 The outer articulatory surface is triangular, concave, and 

 looks slightly backwards, and is in contact with the under 

 surface of the outer cartilage and with the outer condyle. 

 The inferior extremity is c^uadrilateral and consists of two 

 articular grooves running obliquely from within outwards 

 and forwards, which come in contact with the sujDcrior 

 articulatory surface of astragalus. The inner groove is the 

 deepest and the narrowest and extends farthest backwards. 

 The outer in some cases consists of two portions of bone con- 

 nected by fibrous tissue, tlie outer of tJiem being the inferior 

 extremity of the fibula. The outer margin is rough and pro- 

 minent, being termed the outer malleolus, over which a 

 groove for peroneus runs downwards. It affords attach- 

 ment to the capsular, outer lateral and supero-anterior 

 annular ligament of the hock. The ijosterior margin is 

 rough for attachment of the capsular ligament, and 

 comes to a point centrally. The inner margin is 

 rough, and posteriorly presents a groove running 

 from above downwards for flexor pedis accessorius, 

 anteriorly the internal malleolus, larger than the outer, 

 which gives attachment to the inner lateral and capsular 

 ligaments. The anterior margin is straight, and rough for 

 attachment of the capsular ligament. 



The FIBULA is a small very much elongated piece 

 of bone, situated at the external part of the tibia, 

 rounded for the most part and by its inner part con- 

 nected with the tibia by white fibrous tissue, some- 

 times continued as far as the true hock joint. Some- 

 times its middle part degenerates into a white 

 fibrous band. Superiorly it slightly expands in forming 

 a button-like extremity flattened from without inwards, 

 the inner surface of which is roughened for attachment 

 of white fibrous tissue connecting it to the suj)ero- external 



