48 PRINCIPLES OF VETERINARY SCIENCE 



bone, where it becomes flattened; the posterior surface presents 

 several rough ridges and the nutrient foramen. The anterior bor- 

 der is prominent and forms the tibial crest. The upper extremity 

 is large, three sided, and shows two saddle-shaped surfaces for 

 articulation with the condyles of the femur; centrally, there is 

 a pointed prominence; externally, there is a rough facet for the 

 head of the fibula. The distal extremity carries an articular sur- 

 face composed of two deep furrows with a ridge between for the 

 tibial tarsal bone. 



The fibula is a reduced long bone situated along the outer border 

 of the tibia, with which it articulates at the proximal extremity. 

 The distal extremity ends as bone about the lower third of the 

 tibia, but is continued by a fibrous cord to the distal end of the 

 tibia. 



The tarsus, or hock, is composed of a collection of short bones 

 situated between the tibia and the metatarsus. There are six 

 or seven bones in the group, arranged in two rows, with a central 

 bone between. The upper row is made up of the tibial and fibular 

 tarsal bones, below which lies the central. The lower row is 

 made up of the fused first and second, third and fourth tarsal 

 bones. 1 The fibular tarsal is the largest and consists of a body 

 provided with facets for articulation with the adjoining bones. 

 Projecting upward and backward from the body is a prominence 

 which corresponds to the heel of man. In the horse it forms 

 the point of the hock. The tibial tarsal or knuckle-bone is the 

 inner bone of the upper row. Its superior and anterior surfaces 

 are continuous and form a trochlea consisting of two ridges, with 

 a furrow between, for articulation with the distal end of the tibia. 

 The central tarsal is situated between the two rows. The first 

 and second are usually united to form a single bone. The third 

 is somewhat like the central in form and appearance. The fourth 

 is cubical in shape. 



The metatarsus is composed, like the corresponding region 

 in the fore limb, of the cannon and two splint bones. These bones 

 are directed downward and a little forward. The hind cannon 

 is about one-sixth longer than the fore. On cross-section it is 

 more nearly circular in outline. The splints are larger and 

 stronger,the external being relatively massive. 



1 These names apply when viewing the hock from the front and from within 

 outward. 



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